1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
//! Implementation of lint checking.
//!
//! The lint checking is mostly consolidated into one pass which runs
//! after all other analyses. Throughout compilation, lint warnings
//! can be added via the `add_lint` method on the Session structure. This
//! requires a span and an ID of the node that the lint is being added to. The
//! lint isn't actually emitted at that time because it is unknown what the
//! actual lint level at that location is.
//!
//! To actually emit lint warnings/errors, a separate pass is used.
//! A context keeps track of the current state of all lint levels.
//! Upon entering a node of the ast which can modify the lint settings, the
//! previous lint state is pushed onto a stack and the ast is then recursed
//! upon. As the ast is traversed, this keeps track of the current lint level
//! for all lint attributes.

use crate::context::{EarlyContext, LintContext, LintStore};
use crate::passes::{EarlyLintPass, EarlyLintPassObject};
use rustc_ast::ptr::P;
use rustc_ast::visit::{self as ast_visit, Visitor};
use rustc_ast::{self as ast, walk_list, HasAttrs};
use rustc_middle::ty::RegisteredTools;
use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
use rustc_session::Session;
use rustc_span::symbol::Ident;
use rustc_span::Span;

use std::slice;
use tracing::debug;

macro_rules! run_early_pass { ($cx:expr, $f:ident, $($args:expr),*) => ({
    $cx.pass.$f(&$cx.context, $($args),*);
}) }

pub struct EarlyContextAndPass<'a, T: EarlyLintPass> {
    context: EarlyContext<'a>,
    pass: T,
}

impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
    fn check_id(&mut self, id: ast::NodeId) {
        for early_lint in self.context.buffered.take(id) {
            let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
            self.context.lookup_with_diagnostics(
                lint_id.lint,
                Some(span),
                |lint| {
                    lint.build(&msg).emit();
                },
                diagnostic,
            );
        }
    }

    /// Merge the lints specified by any lint attributes into the
    /// current lint context, call the provided function, then reset the
    /// lints in effect to their previous state.
    fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
    where
        F: FnOnce(&mut Self),
    {
        let is_crate_node = id == ast::CRATE_NODE_ID;
        let push = self.context.builder.push(attrs, is_crate_node, None);

        self.check_id(id);
        debug!("early context: enter_attrs({:?})", attrs);
        run_early_pass!(self, enter_lint_attrs, attrs);
        f(self);
        debug!("early context: exit_attrs({:?})", attrs);
        run_early_pass!(self, exit_lint_attrs, attrs);
        self.context.builder.pop(push);
    }
}

impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
    fn visit_param(&mut self, param: &'a ast::Param) {
        self.with_lint_attrs(param.id, &param.attrs, |cx| {
            run_early_pass!(cx, check_param, param);
            ast_visit::walk_param(cx, param);
        });
    }

    fn visit_item(&mut self, it: &'a ast::Item) {
        self.with_lint_attrs(it.id, &it.attrs, |cx| {
            run_early_pass!(cx, check_item, it);
            ast_visit::walk_item(cx, it);
            run_early_pass!(cx, check_item_post, it);
        })
    }

    fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
        self.with_lint_attrs(it.id, &it.attrs, |cx| {
            ast_visit::walk_foreign_item(cx, it);
        })
    }

    fn visit_pat(&mut self, p: &'a ast::Pat) {
        run_early_pass!(self, check_pat, p);
        self.check_id(p.id);
        ast_visit::walk_pat(self, p);
        run_early_pass!(self, check_pat_post, p);
    }

    fn visit_pat_field(&mut self, field: &'a ast::PatField) {
        self.with_lint_attrs(field.id, &field.attrs, |cx| {
            ast_visit::walk_pat_field(cx, field);
        });
    }

    fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
        self.check_id(c.id);
        ast_visit::walk_anon_const(self, c);
    }

    fn visit_expr(&mut self, e: &'a ast::Expr) {
        self.with_lint_attrs(e.id, &e.attrs, |cx| {
            run_early_pass!(cx, check_expr, e);
            ast_visit::walk_expr(cx, e);
        })
    }

    fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
        self.with_lint_attrs(f.id, &f.attrs, |cx| {
            ast_visit::walk_expr_field(cx, f);
        })
    }

    fn visit_stmt(&mut self, s: &'a ast::Stmt) {
        // Add the statement's lint attributes to our
        // current state when checking the statement itself.
        // This allows us to handle attributes like
        // `#[allow(unused_doc_comments)]`, which apply to
        // sibling attributes on the same target
        //
        // Note that statements get their attributes from
        // the AST struct that they wrap (e.g. an item)
        self.with_lint_attrs(s.id, s.attrs(), |cx| {
            run_early_pass!(cx, check_stmt, s);
            cx.check_id(s.id);
        });
        // The visitor for the AST struct wrapped
        // by the statement (e.g. `Item`) will call
        // `with_lint_attrs`, so do this walk
        // outside of the above `with_lint_attrs` call
        ast_visit::walk_stmt(self, s);
    }

    fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
        run_early_pass!(self, check_fn, fk, span, id);
        self.check_id(id);
        ast_visit::walk_fn(self, fk, span);

        // Explicitly check for lints associated with 'closure_id', since
        // it does not have a corresponding AST node
        if let ast_visit::FnKind::Fn(_, _, sig, _, _, _) = fk {
            if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
                self.check_id(closure_id);
            }
        }
    }

    fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
        if let Some(ctor_hir_id) = s.ctor_id() {
            self.check_id(ctor_hir_id);
        }
        ast_visit::walk_struct_def(self, s);
    }

    fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
        self.with_lint_attrs(s.id, &s.attrs, |cx| {
            ast_visit::walk_field_def(cx, s);
        })
    }

    fn visit_variant(&mut self, v: &'a ast::Variant) {
        self.with_lint_attrs(v.id, &v.attrs, |cx| {
            run_early_pass!(cx, check_variant, v);
            ast_visit::walk_variant(cx, v);
        })
    }

    fn visit_ty(&mut self, t: &'a ast::Ty) {
        run_early_pass!(self, check_ty, t);
        self.check_id(t.id);
        ast_visit::walk_ty(self, t);
    }

    fn visit_ident(&mut self, ident: Ident) {
        run_early_pass!(self, check_ident, ident);
    }

    fn visit_local(&mut self, l: &'a ast::Local) {
        self.with_lint_attrs(l.id, &l.attrs, |cx| {
            run_early_pass!(cx, check_local, l);
            ast_visit::walk_local(cx, l);
        })
    }

    fn visit_block(&mut self, b: &'a ast::Block) {
        run_early_pass!(self, check_block, b);
        self.check_id(b.id);
        ast_visit::walk_block(self, b);
    }

    fn visit_arm(&mut self, a: &'a ast::Arm) {
        self.with_lint_attrs(a.id, &a.attrs, |cx| {
            run_early_pass!(cx, check_arm, a);
            ast_visit::walk_arm(cx, a);
        })
    }

    fn visit_expr_post(&mut self, e: &'a ast::Expr) {
        // Explicitly check for lints associated with 'closure_id', since
        // it does not have a corresponding AST node
        match e.kind {
            ast::ExprKind::Closure(_, _, ast::Async::Yes { closure_id, .. }, ..)
            | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
            _ => {}
        }
    }

    fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
        run_early_pass!(self, check_generic_arg, arg);
        ast_visit::walk_generic_arg(self, arg);
    }

    fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
        self.with_lint_attrs(param.id, &param.attrs, |cx| {
            run_early_pass!(cx, check_generic_param, param);
            ast_visit::walk_generic_param(cx, param);
        });
    }

    fn visit_generics(&mut self, g: &'a ast::Generics) {
        run_early_pass!(self, check_generics, g);
        ast_visit::walk_generics(self, g);
    }

    fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
        ast_visit::walk_where_predicate(self, p);
    }

    fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
        run_early_pass!(self, check_poly_trait_ref, t);
        ast_visit::walk_poly_trait_ref(self, t);
    }

    fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
        self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
            ast_visit::AssocCtxt::Trait => {
                run_early_pass!(cx, check_trait_item, item);
                ast_visit::walk_assoc_item(cx, item, ctxt);
            }
            ast_visit::AssocCtxt::Impl => {
                run_early_pass!(cx, check_impl_item, item);
                ast_visit::walk_assoc_item(cx, item, ctxt);
            }
        });
    }

    fn visit_lifetime(&mut self, lt: &'a ast::Lifetime, _: ast_visit::LifetimeCtxt) {
        self.check_id(lt.id);
    }

    fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
        self.check_id(id);
        ast_visit::walk_path(self, p);
    }

    fn visit_path_segment(&mut self, path_span: Span, s: &'a ast::PathSegment) {
        self.check_id(s.id);
        ast_visit::walk_path_segment(self, path_span, s);
    }

    fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
        run_early_pass!(self, check_attribute, attr);
    }

    fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
        run_early_pass!(self, check_mac_def, mac, id);
        self.check_id(id);
    }

    fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
        run_early_pass!(self, check_mac, mac);
        ast_visit::walk_mac(self, mac);
    }
}

struct EarlyLintPassObjects<'a> {
    lints: &'a mut [EarlyLintPassObject],
}

#[allow(rustc::lint_pass_impl_without_macro)]
impl LintPass for EarlyLintPassObjects<'_> {
    fn name(&self) -> &'static str {
        panic!()
    }
}

macro_rules! expand_early_lint_pass_impl_methods {
    ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
        $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
            for obj in self.lints.iter_mut() {
                obj.$name(context, $($param),*);
            }
        })*
    )
}

macro_rules! early_lint_pass_impl {
    ([], [$($methods:tt)*]) => (
        impl EarlyLintPass for EarlyLintPassObjects<'_> {
            expand_early_lint_pass_impl_methods!([$($methods)*]);
        }
    )
}

crate::early_lint_methods!(early_lint_pass_impl, []);

/// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
/// This trait generalizes over those nodes.
pub trait EarlyCheckNode<'a>: Copy {
    fn id(self) -> ast::NodeId;
    fn attrs<'b>(self) -> &'b [ast::Attribute]
    where
        'a: 'b;
    fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
    where
        'a: 'b;
}

impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
    fn id(self) -> ast::NodeId {
        ast::CRATE_NODE_ID
    }
    fn attrs<'b>(self) -> &'b [ast::Attribute]
    where
        'a: 'b,
    {
        &self.attrs
    }
    fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
    where
        'a: 'b,
    {
        run_early_pass!(cx, check_crate, self);
        ast_visit::walk_crate(cx, self);
        run_early_pass!(cx, check_crate_post, self);
    }
}

impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
    fn id(self) -> ast::NodeId {
        self.0
    }
    fn attrs<'b>(self) -> &'b [ast::Attribute]
    where
        'a: 'b,
    {
        self.1
    }
    fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
    where
        'a: 'b,
    {
        walk_list!(cx, visit_attribute, self.1);
        walk_list!(cx, visit_item, self.2);
    }
}

fn early_lint_node<'a>(
    sess: &Session,
    warn_about_weird_lints: bool,
    lint_store: &LintStore,
    registered_tools: &RegisteredTools,
    buffered: LintBuffer,
    pass: impl EarlyLintPass,
    check_node: impl EarlyCheckNode<'a>,
) -> LintBuffer {
    let mut cx = EarlyContextAndPass {
        context: EarlyContext::new(
            sess,
            warn_about_weird_lints,
            lint_store,
            registered_tools,
            buffered,
        ),
        pass,
    };

    cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
    cx.context.buffered
}

pub fn check_ast_node<'a>(
    sess: &Session,
    pre_expansion: bool,
    lint_store: &LintStore,
    registered_tools: &RegisteredTools,
    lint_buffer: Option<LintBuffer>,
    builtin_lints: impl EarlyLintPass,
    check_node: impl EarlyCheckNode<'a>,
) {
    let passes =
        if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
    let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
    let mut buffered = lint_buffer.unwrap_or_default();

    if sess.opts.unstable_opts.no_interleave_lints {
        for (i, pass) in passes.iter_mut().enumerate() {
            buffered =
                sess.prof.extra_verbose_generic_activity("run_lint", pass.name()).run(|| {
                    early_lint_node(
                        sess,
                        !pre_expansion && i == 0,
                        lint_store,
                        registered_tools,
                        buffered,
                        EarlyLintPassObjects { lints: slice::from_mut(pass) },
                        check_node,
                    )
                });
        }
    } else {
        buffered = early_lint_node(
            sess,
            !pre_expansion,
            lint_store,
            registered_tools,
            buffered,
            builtin_lints,
            check_node,
        );

        if !passes.is_empty() {
            buffered = early_lint_node(
                sess,
                false,
                lint_store,
                registered_tools,
                buffered,
                EarlyLintPassObjects { lints: &mut passes[..] },
                check_node,
            );
        }
    }

    // All of the buffered lints should have been emitted at this point.
    // If not, that means that we somehow buffered a lint for a node id
    // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
    for (id, lints) in buffered.map {
        for early_lint in lints {
            sess.delay_span_bug(
                early_lint.span,
                &format!(
                    "failed to process buffered lint here (dummy = {})",
                    id == ast::DUMMY_NODE_ID
                ),
            );
        }
    }
}