rustc_metadata/rmeta/
encoder.rs

1use std::borrow::Borrow;
2use std::collections::hash_map::Entry;
3use std::fs::File;
4use std::io::{Read, Seek, Write};
5use std::path::{Path, PathBuf};
6use std::sync::Arc;
7
8use rustc_attr_data_structures::EncodeCrossCrate;
9use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
10use rustc_data_structures::memmap::{Mmap, MmapMut};
11use rustc_data_structures::sync::{join, par_for_each_in};
12use rustc_data_structures::temp_dir::MaybeTempDir;
13use rustc_data_structures::thousands::usize_with_underscores;
14use rustc_feature::Features;
15use rustc_hir as hir;
16use rustc_hir::def_id::{CRATE_DEF_ID, CRATE_DEF_INDEX, LOCAL_CRATE, LocalDefId, LocalDefIdSet};
17use rustc_hir::definitions::DefPathData;
18use rustc_hir_pretty::id_to_string;
19use rustc_middle::dep_graph::WorkProductId;
20use rustc_middle::middle::dependency_format::Linkage;
21use rustc_middle::middle::exported_symbols::metadata_symbol_name;
22use rustc_middle::mir::interpret;
23use rustc_middle::query::Providers;
24use rustc_middle::traits::specialization_graph;
25use rustc_middle::ty::codec::TyEncoder;
26use rustc_middle::ty::fast_reject::{self, TreatParams};
27use rustc_middle::ty::{AssocItemContainer, SymbolName};
28use rustc_middle::{bug, span_bug};
29use rustc_serialize::{Decodable, Decoder, Encodable, Encoder, opaque};
30use rustc_session::config::{CrateType, OptLevel, TargetModifier};
31use rustc_span::hygiene::HygieneEncodeContext;
32use rustc_span::{
33    ByteSymbol, ExternalSource, FileName, SourceFile, SpanData, SpanEncoder, StableSourceFileId,
34    Symbol, SyntaxContext, sym,
35};
36use tracing::{debug, instrument, trace};
37
38use crate::errors::{FailCreateFileEncoder, FailWriteFile};
39use crate::rmeta::*;
40
41pub(super) struct EncodeContext<'a, 'tcx> {
42    opaque: opaque::FileEncoder,
43    tcx: TyCtxt<'tcx>,
44    feat: &'tcx rustc_feature::Features,
45    tables: TableBuilders,
46
47    lazy_state: LazyState,
48    span_shorthands: FxHashMap<Span, usize>,
49    type_shorthands: FxHashMap<Ty<'tcx>, usize>,
50    predicate_shorthands: FxHashMap<ty::PredicateKind<'tcx>, usize>,
51
52    interpret_allocs: FxIndexSet<interpret::AllocId>,
53
54    // This is used to speed up Span encoding.
55    // The `usize` is an index into the `MonotonicVec`
56    // that stores the `SourceFile`
57    source_file_cache: (Arc<SourceFile>, usize),
58    // The indices (into the `SourceMap`'s `MonotonicVec`)
59    // of all of the `SourceFiles` that we need to serialize.
60    // When we serialize a `Span`, we insert the index of its
61    // `SourceFile` into the `FxIndexSet`.
62    // The order inside the `FxIndexSet` is used as on-disk
63    // order of `SourceFiles`, and encoded inside `Span`s.
64    required_source_files: Option<FxIndexSet<usize>>,
65    is_proc_macro: bool,
66    hygiene_ctxt: &'a HygieneEncodeContext,
67    // Used for both `Symbol`s and `ByteSymbol`s.
68    symbol_index_table: FxHashMap<u32, usize>,
69}
70
71/// If the current crate is a proc-macro, returns early with `LazyArray::default()`.
72/// This is useful for skipping the encoding of things that aren't needed
73/// for proc-macro crates.
74macro_rules! empty_proc_macro {
75    ($self:ident) => {
76        if $self.is_proc_macro {
77            return LazyArray::default();
78        }
79    };
80}
81
82macro_rules! encoder_methods {
83    ($($name:ident($ty:ty);)*) => {
84        $(fn $name(&mut self, value: $ty) {
85            self.opaque.$name(value)
86        })*
87    }
88}
89
90impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
91    encoder_methods! {
92        emit_usize(usize);
93        emit_u128(u128);
94        emit_u64(u64);
95        emit_u32(u32);
96        emit_u16(u16);
97        emit_u8(u8);
98
99        emit_isize(isize);
100        emit_i128(i128);
101        emit_i64(i64);
102        emit_i32(i32);
103        emit_i16(i16);
104
105        emit_raw_bytes(&[u8]);
106    }
107}
108
109impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyValue<T> {
110    fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
111        e.emit_lazy_distance(self.position);
112    }
113}
114
115impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyArray<T> {
116    fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
117        e.emit_usize(self.num_elems);
118        if self.num_elems > 0 {
119            e.emit_lazy_distance(self.position)
120        }
121    }
122}
123
124impl<'a, 'tcx, I, T> Encodable<EncodeContext<'a, 'tcx>> for LazyTable<I, T> {
125    fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
126        e.emit_usize(self.width);
127        e.emit_usize(self.len);
128        e.emit_lazy_distance(self.position);
129    }
130}
131
132impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for ExpnIndex {
133    fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) {
134        s.emit_u32(self.as_u32());
135    }
136}
137
138impl<'a, 'tcx> SpanEncoder for EncodeContext<'a, 'tcx> {
139    fn encode_crate_num(&mut self, crate_num: CrateNum) {
140        if crate_num != LOCAL_CRATE && self.is_proc_macro {
141            panic!("Attempted to encode non-local CrateNum {crate_num:?} for proc-macro crate");
142        }
143        self.emit_u32(crate_num.as_u32());
144    }
145
146    fn encode_def_index(&mut self, def_index: DefIndex) {
147        self.emit_u32(def_index.as_u32());
148    }
149
150    fn encode_def_id(&mut self, def_id: DefId) {
151        def_id.krate.encode(self);
152        def_id.index.encode(self);
153    }
154
155    fn encode_syntax_context(&mut self, syntax_context: SyntaxContext) {
156        rustc_span::hygiene::raw_encode_syntax_context(syntax_context, self.hygiene_ctxt, self);
157    }
158
159    fn encode_expn_id(&mut self, expn_id: ExpnId) {
160        if expn_id.krate == LOCAL_CRATE {
161            // We will only write details for local expansions. Non-local expansions will fetch
162            // data from the corresponding crate's metadata.
163            // FIXME(#43047) FIXME(#74731) We may eventually want to avoid relying on external
164            // metadata from proc-macro crates.
165            self.hygiene_ctxt.schedule_expn_data_for_encoding(expn_id);
166        }
167        expn_id.krate.encode(self);
168        expn_id.local_id.encode(self);
169    }
170
171    fn encode_span(&mut self, span: Span) {
172        match self.span_shorthands.entry(span) {
173            Entry::Occupied(o) => {
174                // If an offset is smaller than the absolute position, we encode with the offset.
175                // This saves space since smaller numbers encode in less bits.
176                let last_location = *o.get();
177                // This cannot underflow. Metadata is written with increasing position(), so any
178                // previously saved offset must be smaller than the current position.
179                let offset = self.opaque.position() - last_location;
180                if offset < last_location {
181                    let needed = bytes_needed(offset);
182                    SpanTag::indirect(true, needed as u8).encode(self);
183                    self.opaque.write_with(|dest| {
184                        *dest = offset.to_le_bytes();
185                        needed
186                    });
187                } else {
188                    let needed = bytes_needed(last_location);
189                    SpanTag::indirect(false, needed as u8).encode(self);
190                    self.opaque.write_with(|dest| {
191                        *dest = last_location.to_le_bytes();
192                        needed
193                    });
194                }
195            }
196            Entry::Vacant(v) => {
197                let position = self.opaque.position();
198                v.insert(position);
199                // Data is encoded with a SpanTag prefix (see below).
200                span.data().encode(self);
201            }
202        }
203    }
204
205    fn encode_symbol(&mut self, sym: Symbol) {
206        self.encode_symbol_or_byte_symbol(sym.as_u32(), |this| this.emit_str(sym.as_str()));
207    }
208
209    fn encode_byte_symbol(&mut self, byte_sym: ByteSymbol) {
210        self.encode_symbol_or_byte_symbol(byte_sym.as_u32(), |this| {
211            this.emit_byte_str(byte_sym.as_byte_str())
212        });
213    }
214}
215
216fn bytes_needed(n: usize) -> usize {
217    (usize::BITS - n.leading_zeros()).div_ceil(u8::BITS) as usize
218}
219
220impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for SpanData {
221    fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) {
222        // Don't serialize any `SyntaxContext`s from a proc-macro crate,
223        // since we don't load proc-macro dependencies during serialization.
224        // This means that any hygiene information from macros used *within*
225        // a proc-macro crate (e.g. invoking a macro that expands to a proc-macro
226        // definition) will be lost.
227        //
228        // This can show up in two ways:
229        //
230        // 1. Any hygiene information associated with identifier of
231        // a proc macro (e.g. `#[proc_macro] pub fn $name`) will be lost.
232        // Since proc-macros can only be invoked from a different crate,
233        // real code should never need to care about this.
234        //
235        // 2. Using `Span::def_site` or `Span::mixed_site` will not
236        // include any hygiene information associated with the definition
237        // site. This means that a proc-macro cannot emit a `$crate`
238        // identifier which resolves to one of its dependencies,
239        // which also should never come up in practice.
240        //
241        // Additionally, this affects `Span::parent`, and any other
242        // span inspection APIs that would otherwise allow traversing
243        // the `SyntaxContexts` associated with a span.
244        //
245        // None of these user-visible effects should result in any
246        // cross-crate inconsistencies (getting one behavior in the same
247        // crate, and a different behavior in another crate) due to the
248        // limited surface that proc-macros can expose.
249        //
250        // IMPORTANT: If this is ever changed, be sure to update
251        // `rustc_span::hygiene::raw_encode_expn_id` to handle
252        // encoding `ExpnData` for proc-macro crates.
253        let ctxt = if s.is_proc_macro { SyntaxContext::root() } else { self.ctxt };
254
255        if self.is_dummy() {
256            let tag = SpanTag::new(SpanKind::Partial, ctxt, 0);
257            tag.encode(s);
258            if tag.context().is_none() {
259                ctxt.encode(s);
260            }
261            return;
262        }
263
264        // The Span infrastructure should make sure that this invariant holds:
265        debug_assert!(self.lo <= self.hi);
266
267        if !s.source_file_cache.0.contains(self.lo) {
268            let source_map = s.tcx.sess.source_map();
269            let source_file_index = source_map.lookup_source_file_idx(self.lo);
270            s.source_file_cache =
271                (Arc::clone(&source_map.files()[source_file_index]), source_file_index);
272        }
273        let (ref source_file, source_file_index) = s.source_file_cache;
274        debug_assert!(source_file.contains(self.lo));
275
276        if !source_file.contains(self.hi) {
277            // Unfortunately, macro expansion still sometimes generates Spans
278            // that malformed in this way.
279            let tag = SpanTag::new(SpanKind::Partial, ctxt, 0);
280            tag.encode(s);
281            if tag.context().is_none() {
282                ctxt.encode(s);
283            }
284            return;
285        }
286
287        // There are two possible cases here:
288        // 1. This span comes from a 'foreign' crate - e.g. some crate upstream of the
289        // crate we are writing metadata for. When the metadata for *this* crate gets
290        // deserialized, the deserializer will need to know which crate it originally came
291        // from. We use `TAG_VALID_SPAN_FOREIGN` to indicate that a `CrateNum` should
292        // be deserialized after the rest of the span data, which tells the deserializer
293        // which crate contains the source map information.
294        // 2. This span comes from our own crate. No special handling is needed - we just
295        // write `TAG_VALID_SPAN_LOCAL` to let the deserializer know that it should use
296        // our own source map information.
297        //
298        // If we're a proc-macro crate, we always treat this as a local `Span`.
299        // In `encode_source_map`, we serialize foreign `SourceFile`s into our metadata
300        // if we're a proc-macro crate.
301        // This allows us to avoid loading the dependencies of proc-macro crates: all of
302        // the information we need to decode `Span`s is stored in the proc-macro crate.
303        let (kind, metadata_index) = if source_file.is_imported() && !s.is_proc_macro {
304            // To simplify deserialization, we 'rebase' this span onto the crate it originally came
305            // from (the crate that 'owns' the file it references. These rebased 'lo' and 'hi'
306            // values are relative to the source map information for the 'foreign' crate whose
307            // CrateNum we write into the metadata. This allows `imported_source_files` to binary
308            // search through the 'foreign' crate's source map information, using the
309            // deserialized 'lo' and 'hi' values directly.
310            //
311            // All of this logic ensures that the final result of deserialization is a 'normal'
312            // Span that can be used without any additional trouble.
313            let metadata_index = {
314                // Introduce a new scope so that we drop the 'read()' temporary
315                match &*source_file.external_src.read() {
316                    ExternalSource::Foreign { metadata_index, .. } => *metadata_index,
317                    src => panic!("Unexpected external source {src:?}"),
318                }
319            };
320
321            (SpanKind::Foreign, metadata_index)
322        } else {
323            // Record the fact that we need to encode the data for this `SourceFile`
324            let source_files =
325                s.required_source_files.as_mut().expect("Already encoded SourceMap!");
326            let (metadata_index, _) = source_files.insert_full(source_file_index);
327            let metadata_index: u32 =
328                metadata_index.try_into().expect("cannot export more than U32_MAX files");
329
330            (SpanKind::Local, metadata_index)
331        };
332
333        // Encode the start position relative to the file start, so we profit more from the
334        // variable-length integer encoding.
335        let lo = self.lo - source_file.start_pos;
336
337        // Encode length which is usually less than span.hi and profits more
338        // from the variable-length integer encoding that we use.
339        let len = self.hi - self.lo;
340
341        let tag = SpanTag::new(kind, ctxt, len.0 as usize);
342        tag.encode(s);
343        if tag.context().is_none() {
344            ctxt.encode(s);
345        }
346        lo.encode(s);
347        if tag.length().is_none() {
348            len.encode(s);
349        }
350
351        // Encode the index of the `SourceFile` for the span, in order to make decoding faster.
352        metadata_index.encode(s);
353
354        if kind == SpanKind::Foreign {
355            // This needs to be two lines to avoid holding the `s.source_file_cache`
356            // while calling `cnum.encode(s)`
357            let cnum = s.source_file_cache.0.cnum;
358            cnum.encode(s);
359        }
360    }
361}
362
363impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for [u8] {
364    fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
365        Encoder::emit_usize(e, self.len());
366        e.emit_raw_bytes(self);
367    }
368}
369
370impl<'a, 'tcx> TyEncoder<'tcx> for EncodeContext<'a, 'tcx> {
371    const CLEAR_CROSS_CRATE: bool = true;
372
373    fn position(&self) -> usize {
374        self.opaque.position()
375    }
376
377    fn type_shorthands(&mut self) -> &mut FxHashMap<Ty<'tcx>, usize> {
378        &mut self.type_shorthands
379    }
380
381    fn predicate_shorthands(&mut self) -> &mut FxHashMap<ty::PredicateKind<'tcx>, usize> {
382        &mut self.predicate_shorthands
383    }
384
385    fn encode_alloc_id(&mut self, alloc_id: &rustc_middle::mir::interpret::AllocId) {
386        let (index, _) = self.interpret_allocs.insert_full(*alloc_id);
387
388        index.encode(self);
389    }
390}
391
392// Shorthand for `$self.$tables.$table.set_some($def_id.index, $self.lazy($value))`, which would
393// normally need extra variables to avoid errors about multiple mutable borrows.
394macro_rules! record {
395    ($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
396        {
397            let value = $value;
398            let lazy = $self.lazy(value);
399            $self.$tables.$table.set_some($def_id.index, lazy);
400        }
401    }};
402}
403
404// Shorthand for `$self.$tables.$table.set_some($def_id.index, $self.lazy_array($value))`, which would
405// normally need extra variables to avoid errors about multiple mutable borrows.
406macro_rules! record_array {
407    ($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
408        {
409            let value = $value;
410            let lazy = $self.lazy_array(value);
411            $self.$tables.$table.set_some($def_id.index, lazy);
412        }
413    }};
414}
415
416macro_rules! record_defaulted_array {
417    ($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
418        {
419            let value = $value;
420            let lazy = $self.lazy_array(value);
421            $self.$tables.$table.set($def_id.index, lazy);
422        }
423    }};
424}
425
426impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
427    fn emit_lazy_distance(&mut self, position: NonZero<usize>) {
428        let pos = position.get();
429        let distance = match self.lazy_state {
430            LazyState::NoNode => bug!("emit_lazy_distance: outside of a metadata node"),
431            LazyState::NodeStart(start) => {
432                let start = start.get();
433                assert!(pos <= start);
434                start - pos
435            }
436            LazyState::Previous(last_pos) => {
437                assert!(
438                    last_pos <= position,
439                    "make sure that the calls to `lazy*` \
440                     are in the same order as the metadata fields",
441                );
442                position.get() - last_pos.get()
443            }
444        };
445        self.lazy_state = LazyState::Previous(NonZero::new(pos).unwrap());
446        self.emit_usize(distance);
447    }
448
449    fn lazy<T: ParameterizedOverTcx, B: Borrow<T::Value<'tcx>>>(&mut self, value: B) -> LazyValue<T>
450    where
451        T::Value<'tcx>: Encodable<EncodeContext<'a, 'tcx>>,
452    {
453        let pos = NonZero::new(self.position()).unwrap();
454
455        assert_eq!(self.lazy_state, LazyState::NoNode);
456        self.lazy_state = LazyState::NodeStart(pos);
457        value.borrow().encode(self);
458        self.lazy_state = LazyState::NoNode;
459
460        assert!(pos.get() <= self.position());
461
462        LazyValue::from_position(pos)
463    }
464
465    fn lazy_array<T: ParameterizedOverTcx, I: IntoIterator<Item = B>, B: Borrow<T::Value<'tcx>>>(
466        &mut self,
467        values: I,
468    ) -> LazyArray<T>
469    where
470        T::Value<'tcx>: Encodable<EncodeContext<'a, 'tcx>>,
471    {
472        let pos = NonZero::new(self.position()).unwrap();
473
474        assert_eq!(self.lazy_state, LazyState::NoNode);
475        self.lazy_state = LazyState::NodeStart(pos);
476        let len = values.into_iter().map(|value| value.borrow().encode(self)).count();
477        self.lazy_state = LazyState::NoNode;
478
479        assert!(pos.get() <= self.position());
480
481        LazyArray::from_position_and_num_elems(pos, len)
482    }
483
484    fn encode_symbol_or_byte_symbol(
485        &mut self,
486        index: u32,
487        emit_str_or_byte_str: impl Fn(&mut Self),
488    ) {
489        // if symbol/byte symbol is predefined, emit tag and symbol index
490        if Symbol::is_predefined(index) {
491            self.opaque.emit_u8(SYMBOL_PREDEFINED);
492            self.opaque.emit_u32(index);
493        } else {
494            // otherwise write it as string or as offset to it
495            match self.symbol_index_table.entry(index) {
496                Entry::Vacant(o) => {
497                    self.opaque.emit_u8(SYMBOL_STR);
498                    let pos = self.opaque.position();
499                    o.insert(pos);
500                    emit_str_or_byte_str(self);
501                }
502                Entry::Occupied(o) => {
503                    let x = *o.get();
504                    self.emit_u8(SYMBOL_OFFSET);
505                    self.emit_usize(x);
506                }
507            }
508        }
509    }
510
511    fn encode_def_path_table(&mut self) {
512        let table = self.tcx.def_path_table();
513        if self.is_proc_macro {
514            for def_index in std::iter::once(CRATE_DEF_INDEX)
515                .chain(self.tcx.resolutions(()).proc_macros.iter().map(|p| p.local_def_index))
516            {
517                let def_key = self.lazy(table.def_key(def_index));
518                let def_path_hash = table.def_path_hash(def_index);
519                self.tables.def_keys.set_some(def_index, def_key);
520                self.tables.def_path_hashes.set(def_index, def_path_hash.local_hash().as_u64());
521            }
522        } else {
523            for (def_index, def_key, def_path_hash) in table.enumerated_keys_and_path_hashes() {
524                let def_key = self.lazy(def_key);
525                self.tables.def_keys.set_some(def_index, def_key);
526                self.tables.def_path_hashes.set(def_index, def_path_hash.local_hash().as_u64());
527            }
528        }
529    }
530
531    fn encode_def_path_hash_map(&mut self) -> LazyValue<DefPathHashMapRef<'static>> {
532        self.lazy(DefPathHashMapRef::BorrowedFromTcx(self.tcx.def_path_hash_to_def_index_map()))
533    }
534
535    fn encode_source_map(&mut self) -> LazyTable<u32, Option<LazyValue<rustc_span::SourceFile>>> {
536        let source_map = self.tcx.sess.source_map();
537        let all_source_files = source_map.files();
538
539        // By replacing the `Option` with `None`, we ensure that we can't
540        // accidentally serialize any more `Span`s after the source map encoding
541        // is done.
542        let required_source_files = self.required_source_files.take().unwrap();
543
544        let working_directory = &self.tcx.sess.opts.working_dir;
545
546        let mut adapted = TableBuilder::default();
547
548        let local_crate_stable_id = self.tcx.stable_crate_id(LOCAL_CRATE);
549
550        // Only serialize `SourceFile`s that were used during the encoding of a `Span`.
551        //
552        // The order in which we encode source files is important here: the on-disk format for
553        // `Span` contains the index of the corresponding `SourceFile`.
554        for (on_disk_index, &source_file_index) in required_source_files.iter().enumerate() {
555            let source_file = &all_source_files[source_file_index];
556            // Don't serialize imported `SourceFile`s, unless we're in a proc-macro crate.
557            assert!(!source_file.is_imported() || self.is_proc_macro);
558
559            // At export time we expand all source file paths to absolute paths because
560            // downstream compilation sessions can have a different compiler working
561            // directory, so relative paths from this or any other upstream crate
562            // won't be valid anymore.
563            //
564            // At this point we also erase the actual on-disk path and only keep
565            // the remapped version -- as is necessary for reproducible builds.
566            let mut adapted_source_file = (**source_file).clone();
567
568            match source_file.name {
569                FileName::Real(ref original_file_name) => {
570                    let adapted_file_name = source_map
571                        .path_mapping()
572                        .to_embeddable_absolute_path(original_file_name.clone(), working_directory);
573
574                    adapted_source_file.name = FileName::Real(adapted_file_name);
575                }
576                _ => {
577                    // expanded code, not from a file
578                }
579            };
580
581            // We're serializing this `SourceFile` into our crate metadata,
582            // so mark it as coming from this crate.
583            // This also ensures that we don't try to deserialize the
584            // `CrateNum` for a proc-macro dependency - since proc macro
585            // dependencies aren't loaded when we deserialize a proc-macro,
586            // trying to remap the `CrateNum` would fail.
587            if self.is_proc_macro {
588                adapted_source_file.cnum = LOCAL_CRATE;
589            }
590
591            // Update the `StableSourceFileId` to make sure it incorporates the
592            // id of the current crate. This way it will be unique within the
593            // crate graph during downstream compilation sessions.
594            adapted_source_file.stable_id = StableSourceFileId::from_filename_for_export(
595                &adapted_source_file.name,
596                local_crate_stable_id,
597            );
598
599            let on_disk_index: u32 =
600                on_disk_index.try_into().expect("cannot export more than U32_MAX files");
601            adapted.set_some(on_disk_index, self.lazy(adapted_source_file));
602        }
603
604        adapted.encode(&mut self.opaque)
605    }
606
607    fn encode_crate_root(&mut self) -> LazyValue<CrateRoot> {
608        let tcx = self.tcx;
609        let mut stats: Vec<(&'static str, usize)> = Vec::with_capacity(32);
610
611        macro_rules! stat {
612            ($label:literal, $f:expr) => {{
613                let orig_pos = self.position();
614                let res = $f();
615                stats.push(($label, self.position() - orig_pos));
616                res
617            }};
618        }
619
620        // We have already encoded some things. Get their combined size from the current position.
621        stats.push(("preamble", self.position()));
622
623        let (crate_deps, dylib_dependency_formats) =
624            stat!("dep", || (self.encode_crate_deps(), self.encode_dylib_dependency_formats()));
625
626        let lib_features = stat!("lib-features", || self.encode_lib_features());
627
628        let stability_implications =
629            stat!("stability-implications", || self.encode_stability_implications());
630
631        let (lang_items, lang_items_missing) = stat!("lang-items", || {
632            (self.encode_lang_items(), self.encode_lang_items_missing())
633        });
634
635        let stripped_cfg_items = stat!("stripped-cfg-items", || self.encode_stripped_cfg_items());
636
637        let diagnostic_items = stat!("diagnostic-items", || self.encode_diagnostic_items());
638
639        let native_libraries = stat!("native-libs", || self.encode_native_libraries());
640
641        let foreign_modules = stat!("foreign-modules", || self.encode_foreign_modules());
642
643        _ = stat!("def-path-table", || self.encode_def_path_table());
644
645        // Encode the def IDs of traits, for rustdoc and diagnostics.
646        let traits = stat!("traits", || self.encode_traits());
647
648        // Encode the def IDs of impls, for coherence checking.
649        let impls = stat!("impls", || self.encode_impls());
650
651        let incoherent_impls = stat!("incoherent-impls", || self.encode_incoherent_impls());
652
653        _ = stat!("mir", || self.encode_mir());
654
655        _ = stat!("def-ids", || self.encode_def_ids());
656
657        let interpret_alloc_index = stat!("interpret-alloc-index", || {
658            let mut interpret_alloc_index = Vec::new();
659            let mut n = 0;
660            trace!("beginning to encode alloc ids");
661            loop {
662                let new_n = self.interpret_allocs.len();
663                // if we have found new ids, serialize those, too
664                if n == new_n {
665                    // otherwise, abort
666                    break;
667                }
668                trace!("encoding {} further alloc ids", new_n - n);
669                for idx in n..new_n {
670                    let id = self.interpret_allocs[idx];
671                    let pos = self.position() as u64;
672                    interpret_alloc_index.push(pos);
673                    interpret::specialized_encode_alloc_id(self, tcx, id);
674                }
675                n = new_n;
676            }
677            self.lazy_array(interpret_alloc_index)
678        });
679
680        // Encode the proc macro data. This affects `tables`, so we need to do this before we
681        // encode the tables. This overwrites def_keys, so it must happen after
682        // encode_def_path_table.
683        let proc_macro_data = stat!("proc-macro-data", || self.encode_proc_macros());
684
685        let tables = stat!("tables", || self.tables.encode(&mut self.opaque));
686
687        let debugger_visualizers =
688            stat!("debugger-visualizers", || self.encode_debugger_visualizers());
689
690        let exportable_items = stat!("exportable-items", || self.encode_exportable_items());
691
692        let stable_order_of_exportable_impls =
693            stat!("exportable-items", || self.encode_stable_order_of_exportable_impls());
694
695        // Encode exported symbols info. This is prefetched in `encode_metadata`.
696        let (exported_non_generic_symbols, exported_generic_symbols) =
697            stat!("exported-symbols", || {
698                (
699                    self.encode_exported_symbols(tcx.exported_non_generic_symbols(LOCAL_CRATE)),
700                    self.encode_exported_symbols(tcx.exported_generic_symbols(LOCAL_CRATE)),
701                )
702            });
703
704        // Encode the hygiene data.
705        // IMPORTANT: this *must* be the last thing that we encode (other than `SourceMap`). The
706        // process of encoding other items (e.g. `optimized_mir`) may cause us to load data from
707        // the incremental cache. If this causes us to deserialize a `Span`, then we may load
708        // additional `SyntaxContext`s into the global `HygieneData`. Therefore, we need to encode
709        // the hygiene data last to ensure that we encode any `SyntaxContext`s that might be used.
710        let (syntax_contexts, expn_data, expn_hashes) = stat!("hygiene", || self.encode_hygiene());
711
712        let def_path_hash_map = stat!("def-path-hash-map", || self.encode_def_path_hash_map());
713
714        // Encode source_map. This needs to be done last, because encoding `Span`s tells us which
715        // `SourceFiles` we actually need to encode.
716        let source_map = stat!("source-map", || self.encode_source_map());
717        let target_modifiers = stat!("target-modifiers", || self.encode_target_modifiers());
718
719        let root = stat!("final", || {
720            let attrs = tcx.hir_krate_attrs();
721            self.lazy(CrateRoot {
722                header: CrateHeader {
723                    name: tcx.crate_name(LOCAL_CRATE),
724                    triple: tcx.sess.opts.target_triple.clone(),
725                    hash: tcx.crate_hash(LOCAL_CRATE),
726                    is_proc_macro_crate: proc_macro_data.is_some(),
727                    is_stub: false,
728                },
729                extra_filename: tcx.sess.opts.cg.extra_filename.clone(),
730                stable_crate_id: tcx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(),
731                required_panic_strategy: tcx.required_panic_strategy(LOCAL_CRATE),
732                panic_in_drop_strategy: tcx.sess.opts.unstable_opts.panic_in_drop,
733                edition: tcx.sess.edition(),
734                has_global_allocator: tcx.has_global_allocator(LOCAL_CRATE),
735                has_alloc_error_handler: tcx.has_alloc_error_handler(LOCAL_CRATE),
736                has_panic_handler: tcx.has_panic_handler(LOCAL_CRATE),
737                has_default_lib_allocator: ast::attr::contains_name(
738                    attrs,
739                    sym::default_lib_allocator,
740                ),
741                proc_macro_data,
742                debugger_visualizers,
743                compiler_builtins: ast::attr::contains_name(attrs, sym::compiler_builtins),
744                needs_allocator: ast::attr::contains_name(attrs, sym::needs_allocator),
745                needs_panic_runtime: ast::attr::contains_name(attrs, sym::needs_panic_runtime),
746                no_builtins: ast::attr::contains_name(attrs, sym::no_builtins),
747                panic_runtime: ast::attr::contains_name(attrs, sym::panic_runtime),
748                profiler_runtime: ast::attr::contains_name(attrs, sym::profiler_runtime),
749                symbol_mangling_version: tcx.sess.opts.get_symbol_mangling_version(),
750
751                crate_deps,
752                dylib_dependency_formats,
753                lib_features,
754                stability_implications,
755                lang_items,
756                diagnostic_items,
757                lang_items_missing,
758                stripped_cfg_items,
759                native_libraries,
760                foreign_modules,
761                source_map,
762                target_modifiers,
763                traits,
764                impls,
765                incoherent_impls,
766                exportable_items,
767                stable_order_of_exportable_impls,
768                exported_non_generic_symbols,
769                exported_generic_symbols,
770                interpret_alloc_index,
771                tables,
772                syntax_contexts,
773                expn_data,
774                expn_hashes,
775                def_path_hash_map,
776                specialization_enabled_in: tcx.specialization_enabled_in(LOCAL_CRATE),
777            })
778        });
779
780        let total_bytes = self.position();
781
782        let computed_total_bytes: usize = stats.iter().map(|(_, size)| size).sum();
783        assert_eq!(total_bytes, computed_total_bytes);
784
785        if tcx.sess.opts.unstable_opts.meta_stats {
786            use std::fmt::Write;
787
788            self.opaque.flush();
789
790            // Rewind and re-read all the metadata to count the zero bytes we wrote.
791            let pos_before_rewind = self.opaque.file().stream_position().unwrap();
792            let mut zero_bytes = 0;
793            self.opaque.file().rewind().unwrap();
794            let file = std::io::BufReader::new(self.opaque.file());
795            for e in file.bytes() {
796                if e.unwrap() == 0 {
797                    zero_bytes += 1;
798                }
799            }
800            assert_eq!(self.opaque.file().stream_position().unwrap(), pos_before_rewind);
801
802            stats.sort_by_key(|&(_, usize)| usize);
803            stats.reverse(); // bigger items first
804
805            let prefix = "meta-stats";
806            let perc = |bytes| (bytes * 100) as f64 / total_bytes as f64;
807
808            let section_w = 23;
809            let size_w = 10;
810            let banner_w = 64;
811
812            // We write all the text into a string and print it with a single
813            // `eprint!`. This is an attempt to minimize interleaved text if multiple
814            // rustc processes are printing macro-stats at the same time (e.g. with
815            // `RUSTFLAGS='-Zmeta-stats' cargo build`). It still doesn't guarantee
816            // non-interleaving, though.
817            let mut s = String::new();
818            _ = writeln!(s, "{prefix} {}", "=".repeat(banner_w));
819            _ = writeln!(s, "{prefix} METADATA STATS: {}", tcx.crate_name(LOCAL_CRATE));
820            _ = writeln!(s, "{prefix} {:<section_w$}{:>size_w$}", "Section", "Size");
821            _ = writeln!(s, "{prefix} {}", "-".repeat(banner_w));
822            for (label, size) in stats {
823                _ = writeln!(
824                    s,
825                    "{prefix} {:<section_w$}{:>size_w$} ({:4.1}%)",
826                    label,
827                    usize_with_underscores(size),
828                    perc(size)
829                );
830            }
831            _ = writeln!(s, "{prefix} {}", "-".repeat(banner_w));
832            _ = writeln!(
833                s,
834                "{prefix} {:<section_w$}{:>size_w$} (of which {:.1}% are zero bytes)",
835                "Total",
836                usize_with_underscores(total_bytes),
837                perc(zero_bytes)
838            );
839            _ = writeln!(s, "{prefix} {}", "=".repeat(banner_w));
840            eprint!("{s}");
841        }
842
843        root
844    }
845}
846
847struct AnalyzeAttrState<'a> {
848    is_exported: bool,
849    is_doc_hidden: bool,
850    features: &'a Features,
851}
852
853/// Returns whether an attribute needs to be recorded in metadata, that is, if it's usable and
854/// useful in downstream crates. Local-only attributes are an obvious example, but some
855/// rustdoc-specific attributes can equally be of use while documenting the current crate only.
856///
857/// Removing these superfluous attributes speeds up compilation by making the metadata smaller.
858///
859/// Note: the `is_exported` parameter is used to cache whether the given `DefId` has a public
860/// visibility: this is a piece of data that can be computed once per defid, and not once per
861/// attribute. Some attributes would only be usable downstream if they are public.
862#[inline]
863fn analyze_attr(attr: &hir::Attribute, state: &mut AnalyzeAttrState<'_>) -> bool {
864    let mut should_encode = false;
865    if let hir::Attribute::Parsed(p) = attr
866        && p.encode_cross_crate() == EncodeCrossCrate::No
867    {
868        // Attributes not marked encode-cross-crate don't need to be encoded for downstream crates.
869    } else if let Some(name) = attr.name()
870        && !rustc_feature::encode_cross_crate(name)
871    {
872        // Attributes not marked encode-cross-crate don't need to be encoded for downstream crates.
873    } else if attr.doc_str().is_some() {
874        // We keep all doc comments reachable to rustdoc because they might be "imported" into
875        // downstream crates if they use `#[doc(inline)]` to copy an item's documentation into
876        // their own.
877        if state.is_exported {
878            should_encode = true;
879        }
880    } else if attr.has_name(sym::doc) {
881        // If this is a `doc` attribute that doesn't have anything except maybe `inline` (as in
882        // `#[doc(inline)]`), then we can remove it. It won't be inlinable in downstream crates.
883        if let Some(item_list) = attr.meta_item_list() {
884            for item in item_list {
885                if !item.has_name(sym::inline) {
886                    should_encode = true;
887                    if item.has_name(sym::hidden) {
888                        state.is_doc_hidden = true;
889                        break;
890                    }
891                }
892            }
893        }
894    } else if let &[sym::diagnostic, seg] = &*attr.path() {
895        should_encode = rustc_feature::is_stable_diagnostic_attribute(seg, state.features);
896    } else {
897        should_encode = true;
898    }
899    should_encode
900}
901
902fn should_encode_span(def_kind: DefKind) -> bool {
903    match def_kind {
904        DefKind::Mod
905        | DefKind::Struct
906        | DefKind::Union
907        | DefKind::Enum
908        | DefKind::Variant
909        | DefKind::Trait
910        | DefKind::TyAlias
911        | DefKind::ForeignTy
912        | DefKind::TraitAlias
913        | DefKind::AssocTy
914        | DefKind::TyParam
915        | DefKind::ConstParam
916        | DefKind::LifetimeParam
917        | DefKind::Fn
918        | DefKind::Const
919        | DefKind::Static { .. }
920        | DefKind::Ctor(..)
921        | DefKind::AssocFn
922        | DefKind::AssocConst
923        | DefKind::Macro(_)
924        | DefKind::ExternCrate
925        | DefKind::Use
926        | DefKind::AnonConst
927        | DefKind::InlineConst
928        | DefKind::OpaqueTy
929        | DefKind::Field
930        | DefKind::Impl { .. }
931        | DefKind::Closure
932        | DefKind::SyntheticCoroutineBody => true,
933        DefKind::ForeignMod | DefKind::GlobalAsm => false,
934    }
935}
936
937fn should_encode_attrs(def_kind: DefKind) -> bool {
938    match def_kind {
939        DefKind::Mod
940        | DefKind::Struct
941        | DefKind::Union
942        | DefKind::Enum
943        | DefKind::Variant
944        | DefKind::Trait
945        | DefKind::TyAlias
946        | DefKind::ForeignTy
947        | DefKind::TraitAlias
948        | DefKind::AssocTy
949        | DefKind::Fn
950        | DefKind::Const
951        | DefKind::Static { nested: false, .. }
952        | DefKind::AssocFn
953        | DefKind::AssocConst
954        | DefKind::Macro(_)
955        | DefKind::Field
956        | DefKind::Impl { .. } => true,
957        // Tools may want to be able to detect their tool lints on
958        // closures from upstream crates, too. This is used by
959        // https://github.com/model-checking/kani and is not a performance
960        // or maintenance issue for us.
961        DefKind::Closure => true,
962        DefKind::SyntheticCoroutineBody => false,
963        DefKind::TyParam
964        | DefKind::ConstParam
965        | DefKind::Ctor(..)
966        | DefKind::ExternCrate
967        | DefKind::Use
968        | DefKind::ForeignMod
969        | DefKind::AnonConst
970        | DefKind::InlineConst
971        | DefKind::OpaqueTy
972        | DefKind::LifetimeParam
973        | DefKind::Static { nested: true, .. }
974        | DefKind::GlobalAsm => false,
975    }
976}
977
978fn should_encode_expn_that_defined(def_kind: DefKind) -> bool {
979    match def_kind {
980        DefKind::Mod
981        | DefKind::Struct
982        | DefKind::Union
983        | DefKind::Enum
984        | DefKind::Variant
985        | DefKind::Trait
986        | DefKind::Impl { .. } => true,
987        DefKind::TyAlias
988        | DefKind::ForeignTy
989        | DefKind::TraitAlias
990        | DefKind::AssocTy
991        | DefKind::TyParam
992        | DefKind::Fn
993        | DefKind::Const
994        | DefKind::ConstParam
995        | DefKind::Static { .. }
996        | DefKind::Ctor(..)
997        | DefKind::AssocFn
998        | DefKind::AssocConst
999        | DefKind::Macro(_)
1000        | DefKind::ExternCrate
1001        | DefKind::Use
1002        | DefKind::ForeignMod
1003        | DefKind::AnonConst
1004        | DefKind::InlineConst
1005        | DefKind::OpaqueTy
1006        | DefKind::Field
1007        | DefKind::LifetimeParam
1008        | DefKind::GlobalAsm
1009        | DefKind::Closure
1010        | DefKind::SyntheticCoroutineBody => false,
1011    }
1012}
1013
1014fn should_encode_visibility(def_kind: DefKind) -> bool {
1015    match def_kind {
1016        DefKind::Mod
1017        | DefKind::Struct
1018        | DefKind::Union
1019        | DefKind::Enum
1020        | DefKind::Variant
1021        | DefKind::Trait
1022        | DefKind::TyAlias
1023        | DefKind::ForeignTy
1024        | DefKind::TraitAlias
1025        | DefKind::AssocTy
1026        | DefKind::Fn
1027        | DefKind::Const
1028        | DefKind::Static { nested: false, .. }
1029        | DefKind::Ctor(..)
1030        | DefKind::AssocFn
1031        | DefKind::AssocConst
1032        | DefKind::Macro(..)
1033        | DefKind::Field => true,
1034        DefKind::Use
1035        | DefKind::ForeignMod
1036        | DefKind::TyParam
1037        | DefKind::ConstParam
1038        | DefKind::LifetimeParam
1039        | DefKind::AnonConst
1040        | DefKind::InlineConst
1041        | DefKind::Static { nested: true, .. }
1042        | DefKind::OpaqueTy
1043        | DefKind::GlobalAsm
1044        | DefKind::Impl { .. }
1045        | DefKind::Closure
1046        | DefKind::ExternCrate
1047        | DefKind::SyntheticCoroutineBody => false,
1048    }
1049}
1050
1051fn should_encode_stability(def_kind: DefKind) -> bool {
1052    match def_kind {
1053        DefKind::Mod
1054        | DefKind::Ctor(..)
1055        | DefKind::Variant
1056        | DefKind::Field
1057        | DefKind::Struct
1058        | DefKind::AssocTy
1059        | DefKind::AssocFn
1060        | DefKind::AssocConst
1061        | DefKind::TyParam
1062        | DefKind::ConstParam
1063        | DefKind::Static { .. }
1064        | DefKind::Const
1065        | DefKind::Fn
1066        | DefKind::ForeignMod
1067        | DefKind::TyAlias
1068        | DefKind::OpaqueTy
1069        | DefKind::Enum
1070        | DefKind::Union
1071        | DefKind::Impl { .. }
1072        | DefKind::Trait
1073        | DefKind::TraitAlias
1074        | DefKind::Macro(..)
1075        | DefKind::ForeignTy => true,
1076        DefKind::Use
1077        | DefKind::LifetimeParam
1078        | DefKind::AnonConst
1079        | DefKind::InlineConst
1080        | DefKind::GlobalAsm
1081        | DefKind::Closure
1082        | DefKind::ExternCrate
1083        | DefKind::SyntheticCoroutineBody => false,
1084    }
1085}
1086
1087/// Whether we should encode MIR. Return a pair, resp. for CTFE and for LLVM.
1088///
1089/// Computing, optimizing and encoding the MIR is a relatively expensive operation.
1090/// We want to avoid this work when not required. Therefore:
1091/// - we only compute `mir_for_ctfe` on items with const-eval semantics;
1092/// - we skip `optimized_mir` for check runs.
1093/// - we only encode `optimized_mir` that could be generated in other crates, that is, a code that
1094///   is either generic or has inline hint, and is reachable from the other crates (contained
1095///   in reachable set).
1096///
1097/// Note: Reachable set describes definitions that might be generated or referenced from other
1098/// crates and it can be used to limit optimized MIR that needs to be encoded. On the other hand,
1099/// the reachable set doesn't have much to say about which definitions might be evaluated at compile
1100/// time in other crates, so it cannot be used to omit CTFE MIR. For example, `f` below is
1101/// unreachable and yet it can be evaluated in other crates:
1102///
1103/// ```
1104/// const fn f() -> usize { 0 }
1105/// pub struct S { pub a: [usize; f()] }
1106/// ```
1107fn should_encode_mir(
1108    tcx: TyCtxt<'_>,
1109    reachable_set: &LocalDefIdSet,
1110    def_id: LocalDefId,
1111) -> (bool, bool) {
1112    match tcx.def_kind(def_id) {
1113        // Constructors
1114        DefKind::Ctor(_, _) => {
1115            let mir_opt_base = tcx.sess.opts.output_types.should_codegen()
1116                || tcx.sess.opts.unstable_opts.always_encode_mir;
1117            (true, mir_opt_base)
1118        }
1119        // Constants
1120        DefKind::AnonConst | DefKind::InlineConst | DefKind::AssocConst | DefKind::Const => {
1121            (true, false)
1122        }
1123        // Coroutines require optimized MIR to compute layout.
1124        DefKind::Closure if tcx.is_coroutine(def_id.to_def_id()) => (false, true),
1125        DefKind::SyntheticCoroutineBody => (false, true),
1126        // Full-fledged functions + closures
1127        DefKind::AssocFn | DefKind::Fn | DefKind::Closure => {
1128            let generics = tcx.generics_of(def_id);
1129            let opt = tcx.sess.opts.unstable_opts.always_encode_mir
1130                || (tcx.sess.opts.output_types.should_codegen()
1131                    && reachable_set.contains(&def_id)
1132                    && (generics.requires_monomorphization(tcx)
1133                        || tcx.cross_crate_inlinable(def_id)));
1134            // The function has a `const` modifier or is in a `const trait`.
1135            let is_const_fn = tcx.is_const_fn(def_id.to_def_id())
1136                || tcx.is_const_default_method(def_id.to_def_id());
1137            (is_const_fn, opt)
1138        }
1139        // The others don't have MIR.
1140        _ => (false, false),
1141    }
1142}
1143
1144fn should_encode_variances<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, def_kind: DefKind) -> bool {
1145    match def_kind {
1146        DefKind::Struct
1147        | DefKind::Union
1148        | DefKind::Enum
1149        | DefKind::OpaqueTy
1150        | DefKind::Fn
1151        | DefKind::Ctor(..)
1152        | DefKind::AssocFn => true,
1153        DefKind::AssocTy => {
1154            // Only encode variances for RPITITs (for traits)
1155            matches!(tcx.opt_rpitit_info(def_id), Some(ty::ImplTraitInTraitData::Trait { .. }))
1156        }
1157        DefKind::Mod
1158        | DefKind::Variant
1159        | DefKind::Field
1160        | DefKind::AssocConst
1161        | DefKind::TyParam
1162        | DefKind::ConstParam
1163        | DefKind::Static { .. }
1164        | DefKind::Const
1165        | DefKind::ForeignMod
1166        | DefKind::Impl { .. }
1167        | DefKind::Trait
1168        | DefKind::TraitAlias
1169        | DefKind::Macro(..)
1170        | DefKind::ForeignTy
1171        | DefKind::Use
1172        | DefKind::LifetimeParam
1173        | DefKind::AnonConst
1174        | DefKind::InlineConst
1175        | DefKind::GlobalAsm
1176        | DefKind::Closure
1177        | DefKind::ExternCrate
1178        | DefKind::SyntheticCoroutineBody => false,
1179        DefKind::TyAlias => tcx.type_alias_is_lazy(def_id),
1180    }
1181}
1182
1183fn should_encode_generics(def_kind: DefKind) -> bool {
1184    match def_kind {
1185        DefKind::Struct
1186        | DefKind::Union
1187        | DefKind::Enum
1188        | DefKind::Variant
1189        | DefKind::Trait
1190        | DefKind::TyAlias
1191        | DefKind::ForeignTy
1192        | DefKind::TraitAlias
1193        | DefKind::AssocTy
1194        | DefKind::Fn
1195        | DefKind::Const
1196        | DefKind::Static { .. }
1197        | DefKind::Ctor(..)
1198        | DefKind::AssocFn
1199        | DefKind::AssocConst
1200        | DefKind::AnonConst
1201        | DefKind::InlineConst
1202        | DefKind::OpaqueTy
1203        | DefKind::Impl { .. }
1204        | DefKind::Field
1205        | DefKind::TyParam
1206        | DefKind::Closure
1207        | DefKind::SyntheticCoroutineBody => true,
1208        DefKind::Mod
1209        | DefKind::ForeignMod
1210        | DefKind::ConstParam
1211        | DefKind::Macro(..)
1212        | DefKind::Use
1213        | DefKind::LifetimeParam
1214        | DefKind::GlobalAsm
1215        | DefKind::ExternCrate => false,
1216    }
1217}
1218
1219fn should_encode_type(tcx: TyCtxt<'_>, def_id: LocalDefId, def_kind: DefKind) -> bool {
1220    match def_kind {
1221        DefKind::Struct
1222        | DefKind::Union
1223        | DefKind::Enum
1224        | DefKind::Variant
1225        | DefKind::Ctor(..)
1226        | DefKind::Field
1227        | DefKind::Fn
1228        | DefKind::Const
1229        | DefKind::Static { nested: false, .. }
1230        | DefKind::TyAlias
1231        | DefKind::ForeignTy
1232        | DefKind::Impl { .. }
1233        | DefKind::AssocFn
1234        | DefKind::AssocConst
1235        | DefKind::Closure
1236        | DefKind::ConstParam
1237        | DefKind::AnonConst
1238        | DefKind::InlineConst
1239        | DefKind::SyntheticCoroutineBody => true,
1240
1241        DefKind::OpaqueTy => {
1242            let origin = tcx.local_opaque_ty_origin(def_id);
1243            if let hir::OpaqueTyOrigin::FnReturn { parent, .. }
1244            | hir::OpaqueTyOrigin::AsyncFn { parent, .. } = origin
1245                && let hir::Node::TraitItem(trait_item) = tcx.hir_node_by_def_id(parent)
1246                && let (_, hir::TraitFn::Required(..)) = trait_item.expect_fn()
1247            {
1248                false
1249            } else {
1250                true
1251            }
1252        }
1253
1254        DefKind::AssocTy => {
1255            let assoc_item = tcx.associated_item(def_id);
1256            match assoc_item.container {
1257                ty::AssocItemContainer::Impl => true,
1258                ty::AssocItemContainer::Trait => assoc_item.defaultness(tcx).has_value(),
1259            }
1260        }
1261        DefKind::TyParam => {
1262            let hir::Node::GenericParam(param) = tcx.hir_node_by_def_id(def_id) else { bug!() };
1263            let hir::GenericParamKind::Type { default, .. } = param.kind else { bug!() };
1264            default.is_some()
1265        }
1266
1267        DefKind::Trait
1268        | DefKind::TraitAlias
1269        | DefKind::Mod
1270        | DefKind::ForeignMod
1271        | DefKind::Macro(..)
1272        | DefKind::Static { nested: true, .. }
1273        | DefKind::Use
1274        | DefKind::LifetimeParam
1275        | DefKind::GlobalAsm
1276        | DefKind::ExternCrate => false,
1277    }
1278}
1279
1280fn should_encode_fn_sig(def_kind: DefKind) -> bool {
1281    match def_kind {
1282        DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn) => true,
1283
1284        DefKind::Struct
1285        | DefKind::Union
1286        | DefKind::Enum
1287        | DefKind::Variant
1288        | DefKind::Field
1289        | DefKind::Const
1290        | DefKind::Static { .. }
1291        | DefKind::Ctor(..)
1292        | DefKind::TyAlias
1293        | DefKind::OpaqueTy
1294        | DefKind::ForeignTy
1295        | DefKind::Impl { .. }
1296        | DefKind::AssocConst
1297        | DefKind::Closure
1298        | DefKind::ConstParam
1299        | DefKind::AnonConst
1300        | DefKind::InlineConst
1301        | DefKind::AssocTy
1302        | DefKind::TyParam
1303        | DefKind::Trait
1304        | DefKind::TraitAlias
1305        | DefKind::Mod
1306        | DefKind::ForeignMod
1307        | DefKind::Macro(..)
1308        | DefKind::Use
1309        | DefKind::LifetimeParam
1310        | DefKind::GlobalAsm
1311        | DefKind::ExternCrate
1312        | DefKind::SyntheticCoroutineBody => false,
1313    }
1314}
1315
1316fn should_encode_constness(def_kind: DefKind) -> bool {
1317    match def_kind {
1318        DefKind::Fn | DefKind::AssocFn | DefKind::Closure | DefKind::Ctor(_, CtorKind::Fn) => true,
1319
1320        DefKind::Struct
1321        | DefKind::Union
1322        | DefKind::Enum
1323        | DefKind::Field
1324        | DefKind::Const
1325        | DefKind::AssocConst
1326        | DefKind::AnonConst
1327        | DefKind::Static { .. }
1328        | DefKind::TyAlias
1329        | DefKind::OpaqueTy
1330        | DefKind::Impl { .. }
1331        | DefKind::ForeignTy
1332        | DefKind::ConstParam
1333        | DefKind::InlineConst
1334        | DefKind::AssocTy
1335        | DefKind::TyParam
1336        | DefKind::Trait
1337        | DefKind::TraitAlias
1338        | DefKind::Mod
1339        | DefKind::ForeignMod
1340        | DefKind::Macro(..)
1341        | DefKind::Use
1342        | DefKind::LifetimeParam
1343        | DefKind::GlobalAsm
1344        | DefKind::ExternCrate
1345        | DefKind::Ctor(_, CtorKind::Const)
1346        | DefKind::Variant
1347        | DefKind::SyntheticCoroutineBody => false,
1348    }
1349}
1350
1351fn should_encode_const(def_kind: DefKind) -> bool {
1352    match def_kind {
1353        DefKind::Const | DefKind::AssocConst | DefKind::AnonConst | DefKind::InlineConst => true,
1354
1355        DefKind::Struct
1356        | DefKind::Union
1357        | DefKind::Enum
1358        | DefKind::Variant
1359        | DefKind::Ctor(..)
1360        | DefKind::Field
1361        | DefKind::Fn
1362        | DefKind::Static { .. }
1363        | DefKind::TyAlias
1364        | DefKind::OpaqueTy
1365        | DefKind::ForeignTy
1366        | DefKind::Impl { .. }
1367        | DefKind::AssocFn
1368        | DefKind::Closure
1369        | DefKind::ConstParam
1370        | DefKind::AssocTy
1371        | DefKind::TyParam
1372        | DefKind::Trait
1373        | DefKind::TraitAlias
1374        | DefKind::Mod
1375        | DefKind::ForeignMod
1376        | DefKind::Macro(..)
1377        | DefKind::Use
1378        | DefKind::LifetimeParam
1379        | DefKind::GlobalAsm
1380        | DefKind::ExternCrate
1381        | DefKind::SyntheticCoroutineBody => false,
1382    }
1383}
1384
1385impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
1386    fn encode_attrs(&mut self, def_id: LocalDefId) {
1387        let tcx = self.tcx;
1388        let mut state = AnalyzeAttrState {
1389            is_exported: tcx.effective_visibilities(()).is_exported(def_id),
1390            is_doc_hidden: false,
1391            features: &tcx.features(),
1392        };
1393        let attr_iter = tcx
1394            .hir_attrs(tcx.local_def_id_to_hir_id(def_id))
1395            .iter()
1396            .filter(|attr| analyze_attr(*attr, &mut state));
1397
1398        record_array!(self.tables.attributes[def_id.to_def_id()] <- attr_iter);
1399
1400        let mut attr_flags = AttrFlags::empty();
1401        if state.is_doc_hidden {
1402            attr_flags |= AttrFlags::IS_DOC_HIDDEN;
1403        }
1404        self.tables.attr_flags.set(def_id.local_def_index, attr_flags);
1405    }
1406
1407    fn encode_def_ids(&mut self) {
1408        self.encode_info_for_mod(CRATE_DEF_ID);
1409
1410        // Proc-macro crates only export proc-macro items, which are looked
1411        // up using `proc_macro_data`
1412        if self.is_proc_macro {
1413            return;
1414        }
1415
1416        let tcx = self.tcx;
1417
1418        for local_id in tcx.iter_local_def_id() {
1419            let def_id = local_id.to_def_id();
1420            let def_kind = tcx.def_kind(local_id);
1421            self.tables.def_kind.set_some(def_id.index, def_kind);
1422
1423            // The `DefCollector` will sometimes create unnecessary `DefId`s
1424            // for trivial const arguments which are directly lowered to
1425            // `ConstArgKind::Path`. We never actually access this `DefId`
1426            // anywhere so we don't need to encode it for other crates.
1427            if def_kind == DefKind::AnonConst
1428                && match tcx.hir_node_by_def_id(local_id) {
1429                    hir::Node::ConstArg(hir::ConstArg { kind, .. }) => match kind {
1430                        // Skip encoding defs for these as they should not have had a `DefId` created
1431                        hir::ConstArgKind::Path(..) | hir::ConstArgKind::Infer(..) => true,
1432                        hir::ConstArgKind::Anon(..) => false,
1433                    },
1434                    _ => false,
1435                }
1436            {
1437                continue;
1438            }
1439
1440            if def_kind == DefKind::Field
1441                && let hir::Node::Field(field) = tcx.hir_node_by_def_id(local_id)
1442                && let Some(anon) = field.default
1443            {
1444                record!(self.tables.default_fields[def_id] <- anon.def_id.to_def_id());
1445            }
1446
1447            if should_encode_span(def_kind) {
1448                let def_span = tcx.def_span(local_id);
1449                record!(self.tables.def_span[def_id] <- def_span);
1450            }
1451            if should_encode_attrs(def_kind) {
1452                self.encode_attrs(local_id);
1453            }
1454            if should_encode_expn_that_defined(def_kind) {
1455                record!(self.tables.expn_that_defined[def_id] <- self.tcx.expn_that_defined(def_id));
1456            }
1457            if should_encode_span(def_kind)
1458                && let Some(ident_span) = tcx.def_ident_span(def_id)
1459            {
1460                record!(self.tables.def_ident_span[def_id] <- ident_span);
1461            }
1462            if def_kind.has_codegen_attrs() {
1463                record!(self.tables.codegen_fn_attrs[def_id] <- self.tcx.codegen_fn_attrs(def_id));
1464            }
1465            if should_encode_visibility(def_kind) {
1466                let vis =
1467                    self.tcx.local_visibility(local_id).map_id(|def_id| def_id.local_def_index);
1468                record!(self.tables.visibility[def_id] <- vis);
1469            }
1470            if should_encode_stability(def_kind) {
1471                self.encode_stability(def_id);
1472                self.encode_const_stability(def_id);
1473                self.encode_default_body_stability(def_id);
1474                self.encode_deprecation(def_id);
1475            }
1476            if should_encode_variances(tcx, def_id, def_kind) {
1477                let v = self.tcx.variances_of(def_id);
1478                record_array!(self.tables.variances_of[def_id] <- v);
1479            }
1480            if should_encode_fn_sig(def_kind) {
1481                record!(self.tables.fn_sig[def_id] <- tcx.fn_sig(def_id));
1482            }
1483            if should_encode_generics(def_kind) {
1484                let g = tcx.generics_of(def_id);
1485                record!(self.tables.generics_of[def_id] <- g);
1486                record!(self.tables.explicit_predicates_of[def_id] <- self.tcx.explicit_predicates_of(def_id));
1487                let inferred_outlives = self.tcx.inferred_outlives_of(def_id);
1488                record_defaulted_array!(self.tables.inferred_outlives_of[def_id] <- inferred_outlives);
1489
1490                for param in &g.own_params {
1491                    if let ty::GenericParamDefKind::Const { has_default: true, .. } = param.kind {
1492                        let default = self.tcx.const_param_default(param.def_id);
1493                        record!(self.tables.const_param_default[param.def_id] <- default);
1494                    }
1495                }
1496            }
1497            if tcx.is_conditionally_const(def_id) {
1498                record!(self.tables.const_conditions[def_id] <- self.tcx.const_conditions(def_id));
1499            }
1500            if should_encode_type(tcx, local_id, def_kind) {
1501                record!(self.tables.type_of[def_id] <- self.tcx.type_of(def_id));
1502            }
1503            if should_encode_constness(def_kind) {
1504                self.tables.constness.set_some(def_id.index, self.tcx.constness(def_id));
1505            }
1506            if let DefKind::Fn | DefKind::AssocFn = def_kind {
1507                self.tables.asyncness.set_some(def_id.index, tcx.asyncness(def_id));
1508                record_array!(self.tables.fn_arg_idents[def_id] <- tcx.fn_arg_idents(def_id));
1509            }
1510            if let Some(name) = tcx.intrinsic(def_id) {
1511                record!(self.tables.intrinsic[def_id] <- name);
1512            }
1513            if let DefKind::TyParam = def_kind {
1514                let default = self.tcx.object_lifetime_default(def_id);
1515                record!(self.tables.object_lifetime_default[def_id] <- default);
1516            }
1517            if let DefKind::Trait = def_kind {
1518                record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
1519                record_defaulted_array!(self.tables.explicit_super_predicates_of[def_id] <-
1520                    self.tcx.explicit_super_predicates_of(def_id).skip_binder());
1521                record_defaulted_array!(self.tables.explicit_implied_predicates_of[def_id] <-
1522                    self.tcx.explicit_implied_predicates_of(def_id).skip_binder());
1523                let module_children = self.tcx.module_children_local(local_id);
1524                record_array!(self.tables.module_children_non_reexports[def_id] <-
1525                    module_children.iter().map(|child| child.res.def_id().index));
1526                if self.tcx.is_const_trait(def_id) {
1527                    record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
1528                        <- self.tcx.explicit_implied_const_bounds(def_id).skip_binder());
1529                }
1530            }
1531            if let DefKind::TraitAlias = def_kind {
1532                record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
1533                record_defaulted_array!(self.tables.explicit_super_predicates_of[def_id] <-
1534                    self.tcx.explicit_super_predicates_of(def_id).skip_binder());
1535                record_defaulted_array!(self.tables.explicit_implied_predicates_of[def_id] <-
1536                    self.tcx.explicit_implied_predicates_of(def_id).skip_binder());
1537            }
1538            if let DefKind::Trait | DefKind::Impl { .. } = def_kind {
1539                let associated_item_def_ids = self.tcx.associated_item_def_ids(def_id);
1540                record_array!(self.tables.associated_item_or_field_def_ids[def_id] <-
1541                    associated_item_def_ids.iter().map(|&def_id| {
1542                        assert!(def_id.is_local());
1543                        def_id.index
1544                    })
1545                );
1546                for &def_id in associated_item_def_ids {
1547                    self.encode_info_for_assoc_item(def_id);
1548                }
1549            }
1550            if let DefKind::Closure | DefKind::SyntheticCoroutineBody = def_kind
1551                && let Some(coroutine_kind) = self.tcx.coroutine_kind(def_id)
1552            {
1553                self.tables.coroutine_kind.set(def_id.index, Some(coroutine_kind))
1554            }
1555            if def_kind == DefKind::Closure
1556                && tcx.type_of(def_id).skip_binder().is_coroutine_closure()
1557            {
1558                let coroutine_for_closure = self.tcx.coroutine_for_closure(def_id);
1559                self.tables
1560                    .coroutine_for_closure
1561                    .set_some(def_id.index, coroutine_for_closure.into());
1562
1563                // If this async closure has a by-move body, record it too.
1564                if tcx.needs_coroutine_by_move_body_def_id(coroutine_for_closure) {
1565                    self.tables.coroutine_by_move_body_def_id.set_some(
1566                        coroutine_for_closure.index,
1567                        self.tcx.coroutine_by_move_body_def_id(coroutine_for_closure).into(),
1568                    );
1569                }
1570            }
1571            if let DefKind::Static { .. } = def_kind {
1572                if !self.tcx.is_foreign_item(def_id) {
1573                    let data = self.tcx.eval_static_initializer(def_id).unwrap();
1574                    record!(self.tables.eval_static_initializer[def_id] <- data);
1575                }
1576            }
1577            if let DefKind::Enum | DefKind::Struct | DefKind::Union = def_kind {
1578                self.encode_info_for_adt(local_id);
1579            }
1580            if let DefKind::Mod = def_kind {
1581                self.encode_info_for_mod(local_id);
1582            }
1583            if let DefKind::Macro(_) = def_kind {
1584                self.encode_info_for_macro(local_id);
1585            }
1586            if let DefKind::TyAlias = def_kind {
1587                self.tables
1588                    .type_alias_is_lazy
1589                    .set(def_id.index, self.tcx.type_alias_is_lazy(def_id));
1590            }
1591            if let DefKind::OpaqueTy = def_kind {
1592                self.encode_explicit_item_bounds(def_id);
1593                self.encode_explicit_item_self_bounds(def_id);
1594                record!(self.tables.opaque_ty_origin[def_id] <- self.tcx.opaque_ty_origin(def_id));
1595                self.encode_precise_capturing_args(def_id);
1596                if tcx.is_conditionally_const(def_id) {
1597                    record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
1598                        <- tcx.explicit_implied_const_bounds(def_id).skip_binder());
1599                }
1600            }
1601            if let DefKind::AnonConst = def_kind {
1602                record!(self.tables.anon_const_kind[def_id] <- self.tcx.anon_const_kind(def_id));
1603            }
1604            if tcx.impl_method_has_trait_impl_trait_tys(def_id)
1605                && let Ok(table) = self.tcx.collect_return_position_impl_trait_in_trait_tys(def_id)
1606            {
1607                record!(self.tables.trait_impl_trait_tys[def_id] <- table);
1608            }
1609            if let DefKind::Impl { .. } | DefKind::Trait = def_kind {
1610                let table = tcx.associated_types_for_impl_traits_in_trait_or_impl(def_id);
1611                record!(self.tables.associated_types_for_impl_traits_in_trait_or_impl[def_id] <- table);
1612            }
1613        }
1614
1615        for (def_id, impls) in &tcx.crate_inherent_impls(()).0.inherent_impls {
1616            record_defaulted_array!(self.tables.inherent_impls[def_id.to_def_id()] <- impls.iter().map(|def_id| {
1617                assert!(def_id.is_local());
1618                def_id.index
1619            }));
1620        }
1621
1622        for (def_id, res_map) in &tcx.resolutions(()).doc_link_resolutions {
1623            record!(self.tables.doc_link_resolutions[def_id.to_def_id()] <- res_map);
1624        }
1625
1626        for (def_id, traits) in &tcx.resolutions(()).doc_link_traits_in_scope {
1627            record_array!(self.tables.doc_link_traits_in_scope[def_id.to_def_id()] <- traits);
1628        }
1629    }
1630
1631    #[instrument(level = "trace", skip(self))]
1632    fn encode_info_for_adt(&mut self, local_def_id: LocalDefId) {
1633        let def_id = local_def_id.to_def_id();
1634        let tcx = self.tcx;
1635        let adt_def = tcx.adt_def(def_id);
1636        record!(self.tables.repr_options[def_id] <- adt_def.repr());
1637
1638        let params_in_repr = self.tcx.params_in_repr(def_id);
1639        record!(self.tables.params_in_repr[def_id] <- params_in_repr);
1640
1641        if adt_def.is_enum() {
1642            let module_children = tcx.module_children_local(local_def_id);
1643            record_array!(self.tables.module_children_non_reexports[def_id] <-
1644                module_children.iter().map(|child| child.res.def_id().index));
1645        } else {
1646            // For non-enum, there is only one variant, and its def_id is the adt's.
1647            debug_assert_eq!(adt_def.variants().len(), 1);
1648            debug_assert_eq!(adt_def.non_enum_variant().def_id, def_id);
1649            // Therefore, the loop over variants will encode its fields as the adt's children.
1650        }
1651
1652        for (idx, variant) in adt_def.variants().iter_enumerated() {
1653            let data = VariantData {
1654                discr: variant.discr,
1655                idx,
1656                ctor: variant.ctor.map(|(kind, def_id)| (kind, def_id.index)),
1657                is_non_exhaustive: variant.is_field_list_non_exhaustive(),
1658            };
1659            record!(self.tables.variant_data[variant.def_id] <- data);
1660
1661            record_array!(self.tables.associated_item_or_field_def_ids[variant.def_id] <- variant.fields.iter().map(|f| {
1662                assert!(f.did.is_local());
1663                f.did.index
1664            }));
1665
1666            for field in &variant.fields {
1667                self.tables.safety.set_some(field.did.index, field.safety);
1668            }
1669
1670            if let Some((CtorKind::Fn, ctor_def_id)) = variant.ctor {
1671                let fn_sig = tcx.fn_sig(ctor_def_id);
1672                // FIXME only encode signature for ctor_def_id
1673                record!(self.tables.fn_sig[variant.def_id] <- fn_sig);
1674            }
1675        }
1676
1677        if let Some(destructor) = tcx.adt_destructor(local_def_id) {
1678            record!(self.tables.adt_destructor[def_id] <- destructor);
1679        }
1680
1681        if let Some(destructor) = tcx.adt_async_destructor(local_def_id) {
1682            record!(self.tables.adt_async_destructor[def_id] <- destructor);
1683        }
1684    }
1685
1686    #[instrument(level = "debug", skip(self))]
1687    fn encode_info_for_mod(&mut self, local_def_id: LocalDefId) {
1688        let tcx = self.tcx;
1689        let def_id = local_def_id.to_def_id();
1690
1691        // If we are encoding a proc-macro crates, `encode_info_for_mod` will
1692        // only ever get called for the crate root. We still want to encode
1693        // the crate root for consistency with other crates (some of the resolver
1694        // code uses it). However, we skip encoding anything relating to child
1695        // items - we encode information about proc-macros later on.
1696        if self.is_proc_macro {
1697            // Encode this here because we don't do it in encode_def_ids.
1698            record!(self.tables.expn_that_defined[def_id] <- tcx.expn_that_defined(local_def_id));
1699        } else {
1700            let module_children = tcx.module_children_local(local_def_id);
1701
1702            record_array!(self.tables.module_children_non_reexports[def_id] <-
1703                module_children.iter().filter(|child| child.reexport_chain.is_empty())
1704                    .map(|child| child.res.def_id().index));
1705
1706            record_defaulted_array!(self.tables.module_children_reexports[def_id] <-
1707                module_children.iter().filter(|child| !child.reexport_chain.is_empty()));
1708        }
1709    }
1710
1711    fn encode_explicit_item_bounds(&mut self, def_id: DefId) {
1712        debug!("EncodeContext::encode_explicit_item_bounds({:?})", def_id);
1713        let bounds = self.tcx.explicit_item_bounds(def_id).skip_binder();
1714        record_defaulted_array!(self.tables.explicit_item_bounds[def_id] <- bounds);
1715    }
1716
1717    fn encode_explicit_item_self_bounds(&mut self, def_id: DefId) {
1718        debug!("EncodeContext::encode_explicit_item_self_bounds({:?})", def_id);
1719        let bounds = self.tcx.explicit_item_self_bounds(def_id).skip_binder();
1720        record_defaulted_array!(self.tables.explicit_item_self_bounds[def_id] <- bounds);
1721    }
1722
1723    #[instrument(level = "debug", skip(self))]
1724    fn encode_info_for_assoc_item(&mut self, def_id: DefId) {
1725        let tcx = self.tcx;
1726        let item = tcx.associated_item(def_id);
1727
1728        self.tables.defaultness.set_some(def_id.index, item.defaultness(tcx));
1729        self.tables.assoc_container.set_some(def_id.index, item.container);
1730
1731        match item.container {
1732            AssocItemContainer::Trait => {
1733                if item.is_type() {
1734                    self.encode_explicit_item_bounds(def_id);
1735                    self.encode_explicit_item_self_bounds(def_id);
1736                    if tcx.is_conditionally_const(def_id) {
1737                        record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
1738                            <- self.tcx.explicit_implied_const_bounds(def_id).skip_binder());
1739                    }
1740                }
1741            }
1742            AssocItemContainer::Impl => {
1743                if let Some(trait_item_def_id) = item.trait_item_def_id {
1744                    self.tables.trait_item_def_id.set_some(def_id.index, trait_item_def_id.into());
1745                }
1746            }
1747        }
1748        if let ty::AssocKind::Type { data: ty::AssocTypeData::Rpitit(rpitit_info) } = item.kind {
1749            record!(self.tables.opt_rpitit_info[def_id] <- rpitit_info);
1750            if matches!(rpitit_info, ty::ImplTraitInTraitData::Trait { .. }) {
1751                record_array!(
1752                    self.tables.assumed_wf_types_for_rpitit[def_id]
1753                        <- self.tcx.assumed_wf_types_for_rpitit(def_id)
1754                );
1755                self.encode_precise_capturing_args(def_id);
1756            }
1757        }
1758    }
1759
1760    fn encode_precise_capturing_args(&mut self, def_id: DefId) {
1761        let Some(precise_capturing_args) = self.tcx.rendered_precise_capturing_args(def_id) else {
1762            return;
1763        };
1764
1765        record_array!(self.tables.rendered_precise_capturing_args[def_id] <- precise_capturing_args);
1766    }
1767
1768    fn encode_mir(&mut self) {
1769        if self.is_proc_macro {
1770            return;
1771        }
1772
1773        let tcx = self.tcx;
1774        let reachable_set = tcx.reachable_set(());
1775
1776        let keys_and_jobs = tcx.mir_keys(()).iter().filter_map(|&def_id| {
1777            let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
1778            if encode_const || encode_opt { Some((def_id, encode_const, encode_opt)) } else { None }
1779        });
1780        for (def_id, encode_const, encode_opt) in keys_and_jobs {
1781            debug_assert!(encode_const || encode_opt);
1782
1783            debug!("EntryBuilder::encode_mir({:?})", def_id);
1784            if encode_opt {
1785                record!(self.tables.optimized_mir[def_id.to_def_id()] <- tcx.optimized_mir(def_id));
1786                self.tables
1787                    .cross_crate_inlinable
1788                    .set(def_id.to_def_id().index, self.tcx.cross_crate_inlinable(def_id));
1789                record!(self.tables.closure_saved_names_of_captured_variables[def_id.to_def_id()]
1790                    <- tcx.closure_saved_names_of_captured_variables(def_id));
1791
1792                if self.tcx.is_coroutine(def_id.to_def_id())
1793                    && let Some(witnesses) = tcx.mir_coroutine_witnesses(def_id)
1794                {
1795                    record!(self.tables.mir_coroutine_witnesses[def_id.to_def_id()] <- witnesses);
1796                }
1797            }
1798            if encode_const {
1799                record!(self.tables.mir_for_ctfe[def_id.to_def_id()] <- tcx.mir_for_ctfe(def_id));
1800
1801                // FIXME(generic_const_exprs): this feels wrong to have in `encode_mir`
1802                let abstract_const = tcx.thir_abstract_const(def_id);
1803                if let Ok(Some(abstract_const)) = abstract_const {
1804                    record!(self.tables.thir_abstract_const[def_id.to_def_id()] <- abstract_const);
1805                }
1806
1807                if should_encode_const(tcx.def_kind(def_id)) {
1808                    let qualifs = tcx.mir_const_qualif(def_id);
1809                    record!(self.tables.mir_const_qualif[def_id.to_def_id()] <- qualifs);
1810                    let body = tcx.hir_maybe_body_owned_by(def_id);
1811                    if let Some(body) = body {
1812                        let const_data = rendered_const(self.tcx, &body, def_id);
1813                        record!(self.tables.rendered_const[def_id.to_def_id()] <- const_data);
1814                    }
1815                }
1816            }
1817            record!(self.tables.promoted_mir[def_id.to_def_id()] <- tcx.promoted_mir(def_id));
1818
1819            if self.tcx.is_coroutine(def_id.to_def_id())
1820                && let Some(witnesses) = tcx.mir_coroutine_witnesses(def_id)
1821            {
1822                record!(self.tables.mir_coroutine_witnesses[def_id.to_def_id()] <- witnesses);
1823            }
1824        }
1825
1826        // Encode all the deduced parameter attributes for everything that has MIR, even for items
1827        // that can't be inlined. But don't if we aren't optimizing in non-incremental mode, to
1828        // save the query traffic.
1829        if tcx.sess.opts.output_types.should_codegen()
1830            && tcx.sess.opts.optimize != OptLevel::No
1831            && tcx.sess.opts.incremental.is_none()
1832        {
1833            for &local_def_id in tcx.mir_keys(()) {
1834                if let DefKind::AssocFn | DefKind::Fn = tcx.def_kind(local_def_id) {
1835                    record_array!(self.tables.deduced_param_attrs[local_def_id.to_def_id()] <-
1836                        self.tcx.deduced_param_attrs(local_def_id.to_def_id()));
1837                }
1838            }
1839        }
1840    }
1841
1842    #[instrument(level = "debug", skip(self))]
1843    fn encode_stability(&mut self, def_id: DefId) {
1844        // The query lookup can take a measurable amount of time in crates with many items. Check if
1845        // the stability attributes are even enabled before using their queries.
1846        if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
1847            if let Some(stab) = self.tcx.lookup_stability(def_id) {
1848                record!(self.tables.lookup_stability[def_id] <- stab)
1849            }
1850        }
1851    }
1852
1853    #[instrument(level = "debug", skip(self))]
1854    fn encode_const_stability(&mut self, def_id: DefId) {
1855        // The query lookup can take a measurable amount of time in crates with many items. Check if
1856        // the stability attributes are even enabled before using their queries.
1857        if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
1858            if let Some(stab) = self.tcx.lookup_const_stability(def_id) {
1859                record!(self.tables.lookup_const_stability[def_id] <- stab)
1860            }
1861        }
1862    }
1863
1864    #[instrument(level = "debug", skip(self))]
1865    fn encode_default_body_stability(&mut self, def_id: DefId) {
1866        // The query lookup can take a measurable amount of time in crates with many items. Check if
1867        // the stability attributes are even enabled before using their queries.
1868        if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
1869            if let Some(stab) = self.tcx.lookup_default_body_stability(def_id) {
1870                record!(self.tables.lookup_default_body_stability[def_id] <- stab)
1871            }
1872        }
1873    }
1874
1875    #[instrument(level = "debug", skip(self))]
1876    fn encode_deprecation(&mut self, def_id: DefId) {
1877        if let Some(depr) = self.tcx.lookup_deprecation(def_id) {
1878            record!(self.tables.lookup_deprecation_entry[def_id] <- depr);
1879        }
1880    }
1881
1882    #[instrument(level = "debug", skip(self))]
1883    fn encode_info_for_macro(&mut self, def_id: LocalDefId) {
1884        let tcx = self.tcx;
1885
1886        let (_, macro_def, _) = tcx.hir_expect_item(def_id).expect_macro();
1887        self.tables.is_macro_rules.set(def_id.local_def_index, macro_def.macro_rules);
1888        record!(self.tables.macro_definition[def_id.to_def_id()] <- &*macro_def.body);
1889    }
1890
1891    fn encode_native_libraries(&mut self) -> LazyArray<NativeLib> {
1892        empty_proc_macro!(self);
1893        let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);
1894        self.lazy_array(used_libraries.iter())
1895    }
1896
1897    fn encode_foreign_modules(&mut self) -> LazyArray<ForeignModule> {
1898        empty_proc_macro!(self);
1899        let foreign_modules = self.tcx.foreign_modules(LOCAL_CRATE);
1900        self.lazy_array(foreign_modules.iter().map(|(_, m)| m).cloned())
1901    }
1902
1903    fn encode_hygiene(&mut self) -> (SyntaxContextTable, ExpnDataTable, ExpnHashTable) {
1904        let mut syntax_contexts: TableBuilder<_, _> = Default::default();
1905        let mut expn_data_table: TableBuilder<_, _> = Default::default();
1906        let mut expn_hash_table: TableBuilder<_, _> = Default::default();
1907
1908        self.hygiene_ctxt.encode(
1909            &mut (&mut *self, &mut syntax_contexts, &mut expn_data_table, &mut expn_hash_table),
1910            |(this, syntax_contexts, _, _), index, ctxt_data| {
1911                syntax_contexts.set_some(index, this.lazy(ctxt_data));
1912            },
1913            |(this, _, expn_data_table, expn_hash_table), index, expn_data, hash| {
1914                if let Some(index) = index.as_local() {
1915                    expn_data_table.set_some(index.as_raw(), this.lazy(expn_data));
1916                    expn_hash_table.set_some(index.as_raw(), this.lazy(hash));
1917                }
1918            },
1919        );
1920
1921        (
1922            syntax_contexts.encode(&mut self.opaque),
1923            expn_data_table.encode(&mut self.opaque),
1924            expn_hash_table.encode(&mut self.opaque),
1925        )
1926    }
1927
1928    fn encode_proc_macros(&mut self) -> Option<ProcMacroData> {
1929        let is_proc_macro = self.tcx.crate_types().contains(&CrateType::ProcMacro);
1930        if is_proc_macro {
1931            let tcx = self.tcx;
1932            let proc_macro_decls_static = tcx.proc_macro_decls_static(()).unwrap().local_def_index;
1933            let stability = tcx.lookup_stability(CRATE_DEF_ID);
1934            let macros =
1935                self.lazy_array(tcx.resolutions(()).proc_macros.iter().map(|p| p.local_def_index));
1936            for (i, span) in self.tcx.sess.psess.proc_macro_quoted_spans() {
1937                let span = self.lazy(span);
1938                self.tables.proc_macro_quoted_spans.set_some(i, span);
1939            }
1940
1941            self.tables.def_kind.set_some(LOCAL_CRATE.as_def_id().index, DefKind::Mod);
1942            record!(self.tables.def_span[LOCAL_CRATE.as_def_id()] <- tcx.def_span(LOCAL_CRATE.as_def_id()));
1943            self.encode_attrs(LOCAL_CRATE.as_def_id().expect_local());
1944            let vis = tcx.local_visibility(CRATE_DEF_ID).map_id(|def_id| def_id.local_def_index);
1945            record!(self.tables.visibility[LOCAL_CRATE.as_def_id()] <- vis);
1946            if let Some(stability) = stability {
1947                record!(self.tables.lookup_stability[LOCAL_CRATE.as_def_id()] <- stability);
1948            }
1949            self.encode_deprecation(LOCAL_CRATE.as_def_id());
1950            if let Some(res_map) = tcx.resolutions(()).doc_link_resolutions.get(&CRATE_DEF_ID) {
1951                record!(self.tables.doc_link_resolutions[LOCAL_CRATE.as_def_id()] <- res_map);
1952            }
1953            if let Some(traits) = tcx.resolutions(()).doc_link_traits_in_scope.get(&CRATE_DEF_ID) {
1954                record_array!(self.tables.doc_link_traits_in_scope[LOCAL_CRATE.as_def_id()] <- traits);
1955            }
1956
1957            // Normally, this information is encoded when we walk the items
1958            // defined in this crate. However, we skip doing that for proc-macro crates,
1959            // so we manually encode just the information that we need
1960            for &proc_macro in &tcx.resolutions(()).proc_macros {
1961                let id = proc_macro;
1962                let proc_macro = tcx.local_def_id_to_hir_id(proc_macro);
1963                let mut name = tcx.hir_name(proc_macro);
1964                let span = tcx.hir_span(proc_macro);
1965                // Proc-macros may have attributes like `#[allow_internal_unstable]`,
1966                // so downstream crates need access to them.
1967                let attrs = tcx.hir_attrs(proc_macro);
1968                let macro_kind = if ast::attr::contains_name(attrs, sym::proc_macro) {
1969                    MacroKind::Bang
1970                } else if ast::attr::contains_name(attrs, sym::proc_macro_attribute) {
1971                    MacroKind::Attr
1972                } else if let Some(attr) = ast::attr::find_by_name(attrs, sym::proc_macro_derive) {
1973                    // This unwrap chain should have been checked by the proc-macro harness.
1974                    name = attr.meta_item_list().unwrap()[0]
1975                        .meta_item()
1976                        .unwrap()
1977                        .ident()
1978                        .unwrap()
1979                        .name;
1980                    MacroKind::Derive
1981                } else {
1982                    bug!("Unknown proc-macro type for item {:?}", id);
1983                };
1984
1985                let mut def_key = self.tcx.hir_def_key(id);
1986                def_key.disambiguated_data.data = DefPathData::MacroNs(name);
1987
1988                let def_id = id.to_def_id();
1989                self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind));
1990                self.tables.proc_macro.set_some(def_id.index, macro_kind);
1991                self.encode_attrs(id);
1992                record!(self.tables.def_keys[def_id] <- def_key);
1993                record!(self.tables.def_ident_span[def_id] <- span);
1994                record!(self.tables.def_span[def_id] <- span);
1995                record!(self.tables.visibility[def_id] <- ty::Visibility::Public);
1996                if let Some(stability) = stability {
1997                    record!(self.tables.lookup_stability[def_id] <- stability);
1998                }
1999            }
2000
2001            Some(ProcMacroData { proc_macro_decls_static, stability, macros })
2002        } else {
2003            None
2004        }
2005    }
2006
2007    fn encode_debugger_visualizers(&mut self) -> LazyArray<DebuggerVisualizerFile> {
2008        empty_proc_macro!(self);
2009        self.lazy_array(
2010            self.tcx
2011                .debugger_visualizers(LOCAL_CRATE)
2012                .iter()
2013                // Erase the path since it may contain privacy sensitive data
2014                // that we don't want to end up in crate metadata.
2015                // The path is only needed for the local crate because of
2016                // `--emit dep-info`.
2017                .map(DebuggerVisualizerFile::path_erased),
2018        )
2019    }
2020
2021    fn encode_crate_deps(&mut self) -> LazyArray<CrateDep> {
2022        empty_proc_macro!(self);
2023
2024        let deps = self
2025            .tcx
2026            .crates(())
2027            .iter()
2028            .map(|&cnum| {
2029                let dep = CrateDep {
2030                    name: self.tcx.crate_name(cnum),
2031                    hash: self.tcx.crate_hash(cnum),
2032                    host_hash: self.tcx.crate_host_hash(cnum),
2033                    kind: self.tcx.dep_kind(cnum),
2034                    extra_filename: self.tcx.extra_filename(cnum).clone(),
2035                    is_private: self.tcx.is_private_dep(cnum),
2036                };
2037                (cnum, dep)
2038            })
2039            .collect::<Vec<_>>();
2040
2041        {
2042            // Sanity-check the crate numbers
2043            let mut expected_cnum = 1;
2044            for &(n, _) in &deps {
2045                assert_eq!(n, CrateNum::new(expected_cnum));
2046                expected_cnum += 1;
2047            }
2048        }
2049
2050        // We're just going to write a list of crate 'name-hash-version's, with
2051        // the assumption that they are numbered 1 to n.
2052        // FIXME (#2166): This is not nearly enough to support correct versioning
2053        // but is enough to get transitive crate dependencies working.
2054        self.lazy_array(deps.iter().map(|(_, dep)| dep))
2055    }
2056
2057    fn encode_target_modifiers(&mut self) -> LazyArray<TargetModifier> {
2058        empty_proc_macro!(self);
2059        let tcx = self.tcx;
2060        self.lazy_array(tcx.sess.opts.gather_target_modifiers())
2061    }
2062
2063    fn encode_lib_features(&mut self) -> LazyArray<(Symbol, FeatureStability)> {
2064        empty_proc_macro!(self);
2065        let tcx = self.tcx;
2066        let lib_features = tcx.lib_features(LOCAL_CRATE);
2067        self.lazy_array(lib_features.to_sorted_vec())
2068    }
2069
2070    fn encode_stability_implications(&mut self) -> LazyArray<(Symbol, Symbol)> {
2071        empty_proc_macro!(self);
2072        let tcx = self.tcx;
2073        let implications = tcx.stability_implications(LOCAL_CRATE);
2074        let sorted = implications.to_sorted_stable_ord();
2075        self.lazy_array(sorted.into_iter().map(|(k, v)| (*k, *v)))
2076    }
2077
2078    fn encode_diagnostic_items(&mut self) -> LazyArray<(Symbol, DefIndex)> {
2079        empty_proc_macro!(self);
2080        let tcx = self.tcx;
2081        let diagnostic_items = &tcx.diagnostic_items(LOCAL_CRATE).name_to_id;
2082        self.lazy_array(diagnostic_items.iter().map(|(&name, def_id)| (name, def_id.index)))
2083    }
2084
2085    fn encode_lang_items(&mut self) -> LazyArray<(DefIndex, LangItem)> {
2086        empty_proc_macro!(self);
2087        let lang_items = self.tcx.lang_items().iter();
2088        self.lazy_array(lang_items.filter_map(|(lang_item, def_id)| {
2089            def_id.as_local().map(|id| (id.local_def_index, lang_item))
2090        }))
2091    }
2092
2093    fn encode_lang_items_missing(&mut self) -> LazyArray<LangItem> {
2094        empty_proc_macro!(self);
2095        let tcx = self.tcx;
2096        self.lazy_array(&tcx.lang_items().missing)
2097    }
2098
2099    fn encode_stripped_cfg_items(&mut self) -> LazyArray<StrippedCfgItem<DefIndex>> {
2100        self.lazy_array(
2101            self.tcx
2102                .stripped_cfg_items(LOCAL_CRATE)
2103                .into_iter()
2104                .map(|item| item.clone().map_mod_id(|def_id| def_id.index)),
2105        )
2106    }
2107
2108    fn encode_traits(&mut self) -> LazyArray<DefIndex> {
2109        empty_proc_macro!(self);
2110        self.lazy_array(self.tcx.traits(LOCAL_CRATE).iter().map(|def_id| def_id.index))
2111    }
2112
2113    /// Encodes an index, mapping each trait to its (local) implementations.
2114    #[instrument(level = "debug", skip(self))]
2115    fn encode_impls(&mut self) -> LazyArray<TraitImpls> {
2116        empty_proc_macro!(self);
2117        let tcx = self.tcx;
2118        let mut trait_impls: FxIndexMap<DefId, Vec<(DefIndex, Option<SimplifiedType>)>> =
2119            FxIndexMap::default();
2120
2121        for id in tcx.hir_free_items() {
2122            let DefKind::Impl { of_trait } = tcx.def_kind(id.owner_id) else {
2123                continue;
2124            };
2125            let def_id = id.owner_id.to_def_id();
2126
2127            self.tables.defaultness.set_some(def_id.index, tcx.defaultness(def_id));
2128
2129            if of_trait && let Some(header) = tcx.impl_trait_header(def_id) {
2130                record!(self.tables.impl_trait_header[def_id] <- header);
2131
2132                let trait_ref = header.trait_ref.instantiate_identity();
2133                let simplified_self_ty = fast_reject::simplify_type(
2134                    self.tcx,
2135                    trait_ref.self_ty(),
2136                    TreatParams::InstantiateWithInfer,
2137                );
2138                trait_impls
2139                    .entry(trait_ref.def_id)
2140                    .or_default()
2141                    .push((id.owner_id.def_id.local_def_index, simplified_self_ty));
2142
2143                let trait_def = tcx.trait_def(trait_ref.def_id);
2144                if let Ok(mut an) = trait_def.ancestors(tcx, def_id) {
2145                    if let Some(specialization_graph::Node::Impl(parent)) = an.nth(1) {
2146                        self.tables.impl_parent.set_some(def_id.index, parent.into());
2147                    }
2148                }
2149
2150                // if this is an impl of `CoerceUnsized`, create its
2151                // "unsized info", else just store None
2152                if tcx.is_lang_item(trait_ref.def_id, LangItem::CoerceUnsized) {
2153                    let coerce_unsized_info = tcx.coerce_unsized_info(def_id).unwrap();
2154                    record!(self.tables.coerce_unsized_info[def_id] <- coerce_unsized_info);
2155                }
2156            }
2157        }
2158
2159        let trait_impls: Vec<_> = trait_impls
2160            .into_iter()
2161            .map(|(trait_def_id, impls)| TraitImpls {
2162                trait_id: (trait_def_id.krate.as_u32(), trait_def_id.index),
2163                impls: self.lazy_array(&impls),
2164            })
2165            .collect();
2166
2167        self.lazy_array(&trait_impls)
2168    }
2169
2170    #[instrument(level = "debug", skip(self))]
2171    fn encode_incoherent_impls(&mut self) -> LazyArray<IncoherentImpls> {
2172        empty_proc_macro!(self);
2173        let tcx = self.tcx;
2174
2175        let all_impls: Vec<_> = tcx
2176            .crate_inherent_impls(())
2177            .0
2178            .incoherent_impls
2179            .iter()
2180            .map(|(&simp, impls)| IncoherentImpls {
2181                self_ty: simp,
2182                impls: self.lazy_array(impls.iter().map(|def_id| def_id.local_def_index)),
2183            })
2184            .collect();
2185
2186        self.lazy_array(&all_impls)
2187    }
2188
2189    fn encode_exportable_items(&mut self) -> LazyArray<DefIndex> {
2190        empty_proc_macro!(self);
2191        self.lazy_array(self.tcx.exportable_items(LOCAL_CRATE).iter().map(|def_id| def_id.index))
2192    }
2193
2194    fn encode_stable_order_of_exportable_impls(&mut self) -> LazyArray<(DefIndex, usize)> {
2195        empty_proc_macro!(self);
2196        let stable_order_of_exportable_impls =
2197            self.tcx.stable_order_of_exportable_impls(LOCAL_CRATE);
2198        self.lazy_array(
2199            stable_order_of_exportable_impls.iter().map(|(def_id, idx)| (def_id.index, *idx)),
2200        )
2201    }
2202
2203    // Encodes all symbols exported from this crate into the metadata.
2204    //
2205    // This pass is seeded off the reachability list calculated in the
2206    // middle::reachable module but filters out items that either don't have a
2207    // symbol associated with them (they weren't translated) or if they're an FFI
2208    // definition (as that's not defined in this crate).
2209    fn encode_exported_symbols(
2210        &mut self,
2211        exported_symbols: &[(ExportedSymbol<'tcx>, SymbolExportInfo)],
2212    ) -> LazyArray<(ExportedSymbol<'static>, SymbolExportInfo)> {
2213        empty_proc_macro!(self);
2214        // The metadata symbol name is special. It should not show up in
2215        // downstream crates.
2216        let metadata_symbol_name = SymbolName::new(self.tcx, &metadata_symbol_name(self.tcx));
2217
2218        self.lazy_array(
2219            exported_symbols
2220                .iter()
2221                .filter(|&(exported_symbol, _)| match *exported_symbol {
2222                    ExportedSymbol::NoDefId(symbol_name) => symbol_name != metadata_symbol_name,
2223                    _ => true,
2224                })
2225                .cloned(),
2226        )
2227    }
2228
2229    fn encode_dylib_dependency_formats(&mut self) -> LazyArray<Option<LinkagePreference>> {
2230        empty_proc_macro!(self);
2231        let formats = self.tcx.dependency_formats(());
2232        if let Some(arr) = formats.get(&CrateType::Dylib) {
2233            return self.lazy_array(arr.iter().skip(1 /* skip LOCAL_CRATE */).map(
2234                |slot| match *slot {
2235                    Linkage::NotLinked | Linkage::IncludedFromDylib => None,
2236
2237                    Linkage::Dynamic => Some(LinkagePreference::RequireDynamic),
2238                    Linkage::Static => Some(LinkagePreference::RequireStatic),
2239                },
2240            ));
2241        }
2242        LazyArray::default()
2243    }
2244}
2245
2246/// Used to prefetch queries which will be needed later by metadata encoding.
2247/// Only a subset of the queries are actually prefetched to keep this code smaller.
2248fn prefetch_mir(tcx: TyCtxt<'_>) {
2249    if !tcx.sess.opts.output_types.should_codegen() {
2250        // We won't emit MIR, so don't prefetch it.
2251        return;
2252    }
2253
2254    let reachable_set = tcx.reachable_set(());
2255    par_for_each_in(tcx.mir_keys(()), |&&def_id| {
2256        let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
2257
2258        if encode_const {
2259            tcx.ensure_done().mir_for_ctfe(def_id);
2260        }
2261        if encode_opt {
2262            tcx.ensure_done().optimized_mir(def_id);
2263        }
2264        if encode_opt || encode_const {
2265            tcx.ensure_done().promoted_mir(def_id);
2266        }
2267    })
2268}
2269
2270// NOTE(eddyb) The following comment was preserved for posterity, even
2271// though it's no longer relevant as EBML (which uses nested & tagged
2272// "documents") was replaced with a scheme that can't go out of bounds.
2273//
2274// And here we run into yet another obscure archive bug: in which metadata
2275// loaded from archives may have trailing garbage bytes. Awhile back one of
2276// our tests was failing sporadically on the macOS 64-bit builders (both nopt
2277// and opt) by having ebml generate an out-of-bounds panic when looking at
2278// metadata.
2279//
2280// Upon investigation it turned out that the metadata file inside of an rlib
2281// (and ar archive) was being corrupted. Some compilations would generate a
2282// metadata file which would end in a few extra bytes, while other
2283// compilations would not have these extra bytes appended to the end. These
2284// extra bytes were interpreted by ebml as an extra tag, so they ended up
2285// being interpreted causing the out-of-bounds.
2286//
2287// The root cause of why these extra bytes were appearing was never
2288// discovered, and in the meantime the solution we're employing is to insert
2289// the length of the metadata to the start of the metadata. Later on this
2290// will allow us to slice the metadata to the precise length that we just
2291// generated regardless of trailing bytes that end up in it.
2292
2293pub struct EncodedMetadata {
2294    // The declaration order matters because `full_metadata` should be dropped
2295    // before `_temp_dir`.
2296    full_metadata: Option<Mmap>,
2297    // This is an optional stub metadata containing only the crate header.
2298    // The header should be very small, so we load it directly into memory.
2299    stub_metadata: Option<Vec<u8>>,
2300    // The path containing the metadata, to record as work product.
2301    path: Option<Box<Path>>,
2302    // We need to carry MaybeTempDir to avoid deleting the temporary
2303    // directory while accessing the Mmap.
2304    _temp_dir: Option<MaybeTempDir>,
2305}
2306
2307impl EncodedMetadata {
2308    #[inline]
2309    pub fn from_path(
2310        path: PathBuf,
2311        stub_path: Option<PathBuf>,
2312        temp_dir: Option<MaybeTempDir>,
2313    ) -> std::io::Result<Self> {
2314        let file = std::fs::File::open(&path)?;
2315        let file_metadata = file.metadata()?;
2316        if file_metadata.len() == 0 {
2317            return Ok(Self {
2318                full_metadata: None,
2319                stub_metadata: None,
2320                path: None,
2321                _temp_dir: None,
2322            });
2323        }
2324        let full_mmap = unsafe { Some(Mmap::map(file)?) };
2325
2326        let stub =
2327            if let Some(stub_path) = stub_path { Some(std::fs::read(stub_path)?) } else { None };
2328
2329        Ok(Self {
2330            full_metadata: full_mmap,
2331            stub_metadata: stub,
2332            path: Some(path.into()),
2333            _temp_dir: temp_dir,
2334        })
2335    }
2336
2337    #[inline]
2338    pub fn full(&self) -> &[u8] {
2339        &self.full_metadata.as_deref().unwrap_or_default()
2340    }
2341
2342    #[inline]
2343    pub fn stub_or_full(&self) -> &[u8] {
2344        self.stub_metadata.as_deref().unwrap_or(self.full())
2345    }
2346
2347    #[inline]
2348    pub fn path(&self) -> Option<&Path> {
2349        self.path.as_deref()
2350    }
2351}
2352
2353impl<S: Encoder> Encodable<S> for EncodedMetadata {
2354    fn encode(&self, s: &mut S) {
2355        self.stub_metadata.encode(s);
2356
2357        let slice = self.full();
2358        slice.encode(s)
2359    }
2360}
2361
2362impl<D: Decoder> Decodable<D> for EncodedMetadata {
2363    fn decode(d: &mut D) -> Self {
2364        let stub = <Option<Vec<u8>>>::decode(d);
2365
2366        let len = d.read_usize();
2367        let full_metadata = if len > 0 {
2368            let mut mmap = MmapMut::map_anon(len).unwrap();
2369            mmap.copy_from_slice(d.read_raw_bytes(len));
2370            Some(mmap.make_read_only().unwrap())
2371        } else {
2372            None
2373        };
2374
2375        Self { full_metadata, stub_metadata: stub, path: None, _temp_dir: None }
2376    }
2377}
2378
2379#[instrument(level = "trace", skip(tcx))]
2380pub fn encode_metadata(tcx: TyCtxt<'_>, path: &Path, ref_path: Option<&Path>) {
2381    // Since encoding metadata is not in a query, and nothing is cached,
2382    // there's no need to do dep-graph tracking for any of it.
2383    tcx.dep_graph.assert_ignored();
2384
2385    // Generate the metadata stub manually, as that is a small file compared to full metadata.
2386    if let Some(ref_path) = ref_path {
2387        let _prof_timer = tcx.prof.verbose_generic_activity("generate_crate_metadata_stub");
2388
2389        with_encode_metadata_header(tcx, ref_path, |ecx| {
2390            let header: LazyValue<CrateHeader> = ecx.lazy(CrateHeader {
2391                name: tcx.crate_name(LOCAL_CRATE),
2392                triple: tcx.sess.opts.target_triple.clone(),
2393                hash: tcx.crate_hash(LOCAL_CRATE),
2394                is_proc_macro_crate: false,
2395                is_stub: true,
2396            });
2397            header.position.get()
2398        })
2399    }
2400
2401    let _prof_timer = tcx.prof.verbose_generic_activity("generate_crate_metadata");
2402
2403    let dep_node = tcx.metadata_dep_node();
2404
2405    // If the metadata dep-node is green, try to reuse the saved work product.
2406    if tcx.dep_graph.is_fully_enabled()
2407        && let work_product_id = WorkProductId::from_cgu_name("metadata")
2408        && let Some(work_product) = tcx.dep_graph.previous_work_product(&work_product_id)
2409        && tcx.try_mark_green(&dep_node)
2410    {
2411        let saved_path = &work_product.saved_files["rmeta"];
2412        let incr_comp_session_dir = tcx.sess.incr_comp_session_dir_opt().unwrap();
2413        let source_file = rustc_incremental::in_incr_comp_dir(&incr_comp_session_dir, saved_path);
2414        debug!("copying preexisting metadata from {source_file:?} to {path:?}");
2415        match rustc_fs_util::link_or_copy(&source_file, path) {
2416            Ok(_) => {}
2417            Err(err) => tcx.dcx().emit_fatal(FailCreateFileEncoder { err }),
2418        };
2419        return;
2420    };
2421
2422    if tcx.sess.threads() != 1 {
2423        // Prefetch some queries used by metadata encoding.
2424        // This is not necessary for correctness, but is only done for performance reasons.
2425        // It can be removed if it turns out to cause trouble or be detrimental to performance.
2426        join(
2427            || prefetch_mir(tcx),
2428            || {
2429                let _ = tcx.exported_non_generic_symbols(LOCAL_CRATE);
2430                let _ = tcx.exported_generic_symbols(LOCAL_CRATE);
2431            },
2432        );
2433    }
2434
2435    // Perform metadata encoding inside a task, so the dep-graph can check if any encoded
2436    // information changes, and maybe reuse the work product.
2437    tcx.dep_graph.with_task(
2438        dep_node,
2439        tcx,
2440        path,
2441        |tcx, path| {
2442            with_encode_metadata_header(tcx, path, |ecx| {
2443                // Encode all the entries and extra information in the crate,
2444                // culminating in the `CrateRoot` which points to all of it.
2445                let root = ecx.encode_crate_root();
2446
2447                // Flush buffer to ensure backing file has the correct size.
2448                ecx.opaque.flush();
2449                // Record metadata size for self-profiling
2450                tcx.prof.artifact_size(
2451                    "crate_metadata",
2452                    "crate_metadata",
2453                    ecx.opaque.file().metadata().unwrap().len(),
2454                );
2455
2456                root.position.get()
2457            })
2458        },
2459        None,
2460    );
2461}
2462
2463fn with_encode_metadata_header(
2464    tcx: TyCtxt<'_>,
2465    path: &Path,
2466    f: impl FnOnce(&mut EncodeContext<'_, '_>) -> usize,
2467) {
2468    let mut encoder = opaque::FileEncoder::new(path)
2469        .unwrap_or_else(|err| tcx.dcx().emit_fatal(FailCreateFileEncoder { err }));
2470    encoder.emit_raw_bytes(METADATA_HEADER);
2471
2472    // Will be filled with the root position after encoding everything.
2473    encoder.emit_raw_bytes(&0u64.to_le_bytes());
2474
2475    let source_map_files = tcx.sess.source_map().files();
2476    let source_file_cache = (Arc::clone(&source_map_files[0]), 0);
2477    let required_source_files = Some(FxIndexSet::default());
2478    drop(source_map_files);
2479
2480    let hygiene_ctxt = HygieneEncodeContext::default();
2481
2482    let mut ecx = EncodeContext {
2483        opaque: encoder,
2484        tcx,
2485        feat: tcx.features(),
2486        tables: Default::default(),
2487        lazy_state: LazyState::NoNode,
2488        span_shorthands: Default::default(),
2489        type_shorthands: Default::default(),
2490        predicate_shorthands: Default::default(),
2491        source_file_cache,
2492        interpret_allocs: Default::default(),
2493        required_source_files,
2494        is_proc_macro: tcx.crate_types().contains(&CrateType::ProcMacro),
2495        hygiene_ctxt: &hygiene_ctxt,
2496        symbol_index_table: Default::default(),
2497    };
2498
2499    // Encode the rustc version string in a predictable location.
2500    rustc_version(tcx.sess.cfg_version).encode(&mut ecx);
2501
2502    let root_position = f(&mut ecx);
2503
2504    // Make sure we report any errors from writing to the file.
2505    // If we forget this, compilation can succeed with an incomplete rmeta file,
2506    // causing an ICE when the rmeta file is read by another compilation.
2507    if let Err((path, err)) = ecx.opaque.finish() {
2508        tcx.dcx().emit_fatal(FailWriteFile { path: &path, err });
2509    }
2510
2511    let file = ecx.opaque.file();
2512    if let Err(err) = encode_root_position(file, root_position) {
2513        tcx.dcx().emit_fatal(FailWriteFile { path: ecx.opaque.path(), err });
2514    }
2515}
2516
2517fn encode_root_position(mut file: &File, pos: usize) -> Result<(), std::io::Error> {
2518    // We will return to this position after writing the root position.
2519    let pos_before_seek = file.stream_position().unwrap();
2520
2521    // Encode the root position.
2522    let header = METADATA_HEADER.len();
2523    file.seek(std::io::SeekFrom::Start(header as u64))?;
2524    file.write_all(&pos.to_le_bytes())?;
2525
2526    // Return to the position where we are before writing the root position.
2527    file.seek(std::io::SeekFrom::Start(pos_before_seek))?;
2528    Ok(())
2529}
2530
2531pub(crate) fn provide(providers: &mut Providers) {
2532    *providers = Providers {
2533        doc_link_resolutions: |tcx, def_id| {
2534            tcx.resolutions(())
2535                .doc_link_resolutions
2536                .get(&def_id)
2537                .unwrap_or_else(|| span_bug!(tcx.def_span(def_id), "no resolutions for a doc link"))
2538        },
2539        doc_link_traits_in_scope: |tcx, def_id| {
2540            tcx.resolutions(()).doc_link_traits_in_scope.get(&def_id).unwrap_or_else(|| {
2541                span_bug!(tcx.def_span(def_id), "no traits in scope for a doc link")
2542            })
2543        },
2544
2545        ..*providers
2546    }
2547}
2548
2549/// Build a textual representation of an unevaluated constant expression.
2550///
2551/// If the const expression is too complex, an underscore `_` is returned.
2552/// For const arguments, it's `{ _ }` to be precise.
2553/// This means that the output is not necessarily valid Rust code.
2554///
2555/// Currently, only
2556///
2557/// * literals (optionally with a leading `-`)
2558/// * unit `()`
2559/// * blocks (`{ … }`) around simple expressions and
2560/// * paths without arguments
2561///
2562/// are considered simple enough. Simple blocks are included since they are
2563/// necessary to disambiguate unit from the unit type.
2564/// This list might get extended in the future.
2565///
2566/// Without this censoring, in a lot of cases the output would get too large
2567/// and verbose. Consider `match` expressions, blocks and deeply nested ADTs.
2568/// Further, private and `doc(hidden)` fields of structs would get leaked
2569/// since HIR datatypes like the `body` parameter do not contain enough
2570/// semantic information for this function to be able to hide them –
2571/// at least not without significant performance overhead.
2572///
2573/// Whenever possible, prefer to evaluate the constant first and try to
2574/// use a different method for pretty-printing. Ideally this function
2575/// should only ever be used as a fallback.
2576pub fn rendered_const<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body<'_>, def_id: LocalDefId) -> String {
2577    let value = body.value;
2578
2579    #[derive(PartialEq, Eq)]
2580    enum Classification {
2581        Literal,
2582        Simple,
2583        Complex,
2584    }
2585
2586    use Classification::*;
2587
2588    fn classify(expr: &hir::Expr<'_>) -> Classification {
2589        match &expr.kind {
2590            hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
2591                if matches!(expr.kind, hir::ExprKind::Lit(_)) { Literal } else { Complex }
2592            }
2593            hir::ExprKind::Lit(_) => Literal,
2594            hir::ExprKind::Tup([]) => Simple,
2595            hir::ExprKind::Block(hir::Block { stmts: [], expr: Some(expr), .. }, _) => {
2596                if classify(expr) == Complex { Complex } else { Simple }
2597            }
2598            // Paths with a self-type or arguments are too “complex” following our measure since
2599            // they may leak private fields of structs (with feature `adt_const_params`).
2600            // Consider: `<Self as Trait<{ Struct { private: () } }>>::CONSTANT`.
2601            // Paths without arguments are definitely harmless though.
2602            hir::ExprKind::Path(hir::QPath::Resolved(_, hir::Path { segments, .. })) => {
2603                if segments.iter().all(|segment| segment.args.is_none()) { Simple } else { Complex }
2604            }
2605            // FIXME: Claiming that those kinds of QPaths are simple is probably not true if the Ty
2606            //        contains const arguments. Is there a *concise* way to check for this?
2607            hir::ExprKind::Path(hir::QPath::TypeRelative(..)) => Simple,
2608            // FIXME: Can they contain const arguments and thus leak private struct fields?
2609            hir::ExprKind::Path(hir::QPath::LangItem(..)) => Simple,
2610            _ => Complex,
2611        }
2612    }
2613
2614    match classify(value) {
2615        // For non-macro literals, we avoid invoking the pretty-printer and use the source snippet
2616        // instead to preserve certain stylistic choices the user likely made for the sake of
2617        // legibility, like:
2618        //
2619        // * hexadecimal notation
2620        // * underscores
2621        // * character escapes
2622        //
2623        // FIXME: This passes through `-/*spacer*/0` verbatim.
2624        Literal
2625            if !value.span.from_expansion()
2626                && let Ok(snippet) = tcx.sess.source_map().span_to_snippet(value.span) =>
2627        {
2628            snippet
2629        }
2630
2631        // Otherwise we prefer pretty-printing to get rid of extraneous whitespace, comments and
2632        // other formatting artifacts.
2633        Literal | Simple => id_to_string(&tcx, body.id().hir_id),
2634
2635        // FIXME: Omit the curly braces if the enclosing expression is an array literal
2636        //        with a repeated element (an `ExprKind::Repeat`) as in such case it
2637        //        would not actually need any disambiguation.
2638        Complex => {
2639            if tcx.def_kind(def_id) == DefKind::AnonConst {
2640                "{ _ }".to_owned()
2641            } else {
2642                "_".to_owned()
2643            }
2644        }
2645    }
2646}