clippy_utils/
msrvs.rs

1use crate::{is_in_const_context, sym};
2use rustc_ast::Attribute;
3use rustc_ast::attr::AttributeExt;
4use rustc_attr_parsing::parse_version;
5use rustc_data_structures::smallvec::SmallVec;
6use rustc_hir::attrs::RustcVersion;
7use rustc_hir::def::DefKind;
8use rustc_hir::def_id::DefId;
9use rustc_hir::{Constness, HirId, StabilityLevel, StableSince};
10use rustc_lint::LateContext;
11use rustc_middle::ty::TyCtxt;
12use rustc_session::Session;
13use std::iter::once;
14use std::sync::atomic::{AtomicBool, Ordering};
15
16macro_rules! msrv_aliases {
17    ($($major:literal,$minor:literal,$patch:literal {
18        $($name:ident),* $(,)?
19    })*) => {
20        $($(
21        pub const $name: RustcVersion = RustcVersion { major: $major, minor :$minor, patch: $patch };
22        )*)*
23    };
24}
25
26// names may refer to stabilized feature flags or library items
27msrv_aliases! {
28    1,97,0 { ISOLATE_LOWEST_ONE, BIT_WIDTH }
29    1,94,0 { EULER_GAMMA, GOLDEN_RATIO }
30    1,93,0 { VEC_DEQUE_POP_BACK_IF, VEC_DEQUE_POP_FRONT_IF }
31    1,91,0 { DURATION_FROM_MINUTES_HOURS }
32    1,89,0 { NONNULL_FROM_MUT }
33    1,88,0 { LET_CHAINS, AS_CHUNKS, RAW_PTR_DEFAULT }
34    1,87,0 { OS_STR_DISPLAY, INT_MIDPOINT, CONST_CHAR_IS_DIGIT, UNSIGNED_IS_MULTIPLE_OF, INTEGER_SIGN_CAST }
35    1,86,0 { VEC_POP_IF }
36    1,85,0 { UINT_FLOAT_MIDPOINT, CONST_SIZE_OF_VAL, WAKER_NOOP }
37    1,84,0 { CONST_OPTION_AS_SLICE, MANUAL_DANGLING_PTR }
38    1,83,0 { CONST_EXTERN_FN, CONST_FLOAT_BITS_CONV, CONST_FLOAT_CLASSIFY, CONST_MUT_REFS, CONST_UNWRAP }
39    1,82,0 { IS_NONE_OR, REPEAT_N, RAW_REF_OP, SPECIALIZED_TO_STRING_FOR_REFS }
40    1,81,0 { LINT_REASONS_STABILIZATION, ERROR_IN_CORE, EXPLICIT_SELF_TYPE_ELISION, DURATION_ABS_DIFF }
41    1,80,0 { BOX_INTO_ITER, LAZY_CELL }
42    1,79,0 { CONST_BLOCKS, CSTR_COUNT_BYTES }
43    1,77,0 { C_STR_LITERALS }
44    1,76,0 { PTR_FROM_REF, OPTION_RESULT_INSPECT }
45    1,75,0 { OPTION_AS_SLICE }
46    1,74,0 { REPR_RUST, IO_ERROR_OTHER }
47    1,73,0 { DIV_CEIL }
48    1,71,0 { TUPLE_ARRAY_CONVERSIONS, BUILD_HASHER_HASH_ONE }
49    1,70,0 { OPTION_RESULT_IS_VARIANT_AND, BINARY_HEAP_RETAIN }
50    1,68,0 { PATH_MAIN_SEPARATOR_STR }
51    1,67,0 { ILOG2 }
52    1,65,0 { LET_ELSE, POINTER_CAST_CONSTNESS }
53    1,63,0 { CLONE_INTO, CONST_SLICE_FROM_REF }
54    1,62,0 { BOOL_THEN_SOME, DEFAULT_ENUM_ATTRIBUTE, CONST_EXTERN_C_FN }
55    1,61,0 { CONST_FN_TRAIT_BOUND }
56    1,60,0 { ABS_DIFF }
57    1,59,0 { THREAD_LOCAL_CONST_INIT }
58    1,58,0 { FORMAT_ARGS_CAPTURE, PATTERN_TRAIT_CHAR_ARRAY, CONST_RAW_PTR_DEREF }
59    1,57,0 { MAP_WHILE, CONST_PANIC }
60    1,56,0 { CONST_FN_UNION }
61    1,55,0 { SEEK_REWIND }
62    1,54,0 { INTO_KEYS }
63    1,53,0 { OR_PATTERNS, INTEGER_BITS, BTREE_MAP_RETAIN, BTREE_SET_RETAIN, ARRAY_INTO_ITERATOR }
64    1,52,0 { STR_SPLIT_ONCE, REM_EUCLID_CONST }
65    1,51,0 { BORROW_AS_PTR, SEEK_FROM_CURRENT, UNSIGNED_ABS }
66    1,50,0 { BOOL_THEN, CLAMP, SLICE_FILL }
67    1,47,0 { TAU, IS_ASCII_DIGIT_CONST, ARRAY_IMPL_ANY_LEN, SATURATING_SUB_CONST }
68    1,46,0 { CONST_IF_MATCH, OPTION_ZIP }
69    1,45,0 { STR_STRIP_PREFIX }
70    1,43,0 { LOG2_10, LOG10_2, NUMERIC_ASSOCIATED_CONSTANTS }
71    1,42,0 { MATCHES_MACRO, SLICE_PATTERNS, PTR_SLICE_RAW_PARTS }
72    1,41,0 { RE_REBALANCING_COHERENCE, RESULT_MAP_OR, RESULT_MAP_OR_ELSE }
73    1,40,0 { MEM_TAKE, NON_EXHAUSTIVE, OPTION_AS_DEREF }
74    1,38,0 { POINTER_CAST, REM_EUCLID }
75    1,37,0 { TYPE_ALIAS_ENUM_VARIANTS }
76    1,36,0 { ITERATOR_COPIED }
77    1,35,0 { OPTION_COPIED, RANGE_CONTAINS }
78    1,34,0 { TRY_FROM }
79    1,33,0 { UNDERSCORE_IMPORTS }
80    1,32,0 { CONST_IS_POWER_OF_TWO, CONST_DURATION_FROM_NANOS_MICROS_MILLIS_SECS }
81    1,31,0 { OPTION_REPLACE }
82    1,30,0 { ITERATOR_FIND_MAP, TOOL_ATTRIBUTES }
83    1,29,0 { ITER_FLATTEN }
84    1,28,0 { FROM_BOOL, REPEAT_WITH, SLICE_FROM_REF }
85    1,27,0 { ITERATOR_TRY_FOLD, DOUBLE_ENDED_ITERATOR_RFIND, DURATION_FROM_NANOS_MICROS }
86    1,26,0 { RANGE_INCLUSIVE, STRING_RETAIN, POINTER_ADD_SUB_METHODS, BOX_LEAK }
87    1,24,0 { IS_ASCII_DIGIT, PTR_NULL }
88    1,18,0 { HASH_MAP_RETAIN, HASH_SET_RETAIN }
89    1,17,0 { FIELD_INIT_SHORTHAND, STATIC_IN_CONST, EXPECT_ERR }
90    1,16,0 { STR_REPEAT, RESULT_UNWRAP_OR_DEFAULT }
91    1,15,0 { MAYBE_BOUND_IN_WHERE }
92    1,13,0 { QUESTION_MARK_OPERATOR }
93    1,3,0 { DURATION_FROM_MILLIS_SECS }
94}
95
96/// `#[clippy::msrv]` attributes are rarely used outside of Clippy's test suite, as a basic
97/// optimization we can skip traversing the HIR in [`Msrv::meets`] if we never saw an MSRV attribute
98/// during the early lint passes
99static SEEN_MSRV_ATTR: AtomicBool = AtomicBool::new(false);
100
101/// Tracks the current MSRV from `clippy.toml`, `Cargo.toml` or set via `#[clippy::msrv]` in late
102/// lint passes, use [`MsrvStack`] for early passes
103#[derive(Copy, Clone, Debug, Default)]
104pub struct Msrv(Option<RustcVersion>);
105
106impl From<Option<RustcVersion>> for Msrv {
107    #[inline]
108    fn from(value: Option<RustcVersion>) -> Self {
109        Self(value)
110    }
111}
112
113impl Msrv {
114    /// Returns the MSRV at the current node
115    ///
116    /// If the crate being linted uses an `#[clippy::msrv]` attribute this will search the parent
117    /// nodes for that attribute, prefer to run this check after cheaper pattern matching operations
118    pub fn current(self, cx: &LateContext<'_>) -> Option<RustcVersion> {
119        if SEEN_MSRV_ATTR.load(Ordering::Relaxed) {
120            self.for_attrs(cx.tcx, cx.last_node_with_lint_attrs)
121        } else {
122            self.0
123        }
124    }
125
126    /// Returns the MSRV at the specified node
127    ///
128    /// If the crate being linted uses an `#[clippy::msrv]` attribute this will search the parent
129    /// nodes for that attribute, prefer to run this check after cheaper pattern matching operations
130    pub fn at(self, tcx: TyCtxt<'_>, node: HirId) -> Option<RustcVersion> {
131        if SEEN_MSRV_ATTR.load(Ordering::Relaxed) {
132            self.for_attrs(tcx, node)
133        } else {
134            self.0
135        }
136    }
137
138    fn for_attrs(self, tcx: TyCtxt<'_>, node: HirId) -> Option<RustcVersion> {
139        once(node)
140            .chain(tcx.hir_parent_id_iter(node))
141            .find_map(|id| parse_attrs(tcx.hir_attrs(id)))
142            .or(self.0)
143    }
144
145    /// Checks if a required version from [this module](self) is met at the current node
146    ///
147    /// If the crate being linted uses an `#[clippy::msrv]` attribute this will search the parent
148    /// nodes for that attribute, prefer to run this check after cheaper pattern matching operations
149    pub fn meets(self, cx: &LateContext<'_>, required: RustcVersion) -> bool {
150        self.current(cx).is_none_or(|msrv| msrv >= required)
151    }
152    /// Checks if a required version from [this module](self) is met at the specified node
153    ///
154    /// If the crate being linted uses an `#[clippy::msrv]` attribute this will search the parent
155    /// nodes for that attribute, prefer to run this check after cheaper pattern matching operations
156    pub fn meets_at(self, tcx: TyCtxt<'_>, node: HirId, required: RustcVersion) -> bool {
157        self.at(tcx, node).is_none_or(|msrv| msrv >= required)
158    }
159
160    pub fn is_stable(self, cx: &LateContext<'_>, def_id: DefId) -> bool {
161        self.stability_met(cx, cx.tcx.lookup_stability(def_id).map(|stability| stability.level))
162    }
163
164    /// Checks whether `def_id` is `const` and const-stable since a version met by the MSRV.
165    ///
166    /// `def_id` must identify a function-like definition or an impl.
167    ///
168    /// Nothing in the crate being linted carries a const-stability attribute, so `const` fns and
169    /// impls defined there are treated as meeting any MSRV, mirroring
170    /// [`is_stable`](Self::is_stable).
171    pub fn is_const_stable(self, cx: &LateContext<'_>, def_id: DefId) -> bool {
172        let constness = match cx.tcx.def_kind(def_id) {
173            // The constness of a trait impl is not encoded in crate metadata, where `constness`
174            // would decode as its default of `Const`. It is only available from the impl header.
175            DefKind::Impl { of_trait: true } => cx.tcx.impl_trait_header(def_id).constness,
176            _ => cx.tcx.constness(def_id),
177        };
178
179        matches!(constness, Constness::Const { .. })
180            && self.stability_met(
181                cx,
182                cx.tcx.lookup_const_stability(def_id).map(|stability| stability.level),
183            )
184    }
185
186    /// Checks the stability relevant to where we are: const-stability inside a `const` context,
187    /// regular stability everywhere else.
188    ///
189    /// Like [`is_in_const_context`], this requires the `LateContext` to have an enclosing body.
190    pub fn is_stable_or_const_stable(self, cx: &LateContext<'_>, def_id: DefId) -> bool {
191        if is_in_const_context(cx) {
192            self.is_const_stable(cx, def_id)
193        } else {
194            self.is_stable(cx, def_id)
195        }
196    }
197
198    fn stability_met(self, cx: &LateContext<'_>, level: Option<StabilityLevel>) -> bool {
199        level.is_none_or(|level| {
200            if let StabilityLevel::Stable { since, .. } = level {
201                let version = match since {
202                    StableSince::Version(version) => version,
203                    StableSince::Current => RustcVersion::CURRENT,
204                    StableSince::Err(_) => return false,
205                };
206
207                self.meets(cx, version)
208            } else {
209                // Unstable fn.
210                // FIXME: can we check that the feature is enabled?
211                // Please see https://github.com/rust-lang/rust-clippy/pull/17309#discussion_r3486693263 for false-positive concerns.
212                false
213            }
214        })
215    }
216}
217
218/// Tracks the current MSRV from `clippy.toml`, `Cargo.toml` or set via `#[clippy::msrv]` in early
219/// lint passes, use [`Msrv`] for late passes
220#[derive(Debug, Clone)]
221pub struct MsrvStack {
222    stack: SmallVec<[RustcVersion; 2]>,
223}
224
225impl From<Option<RustcVersion>> for MsrvStack {
226    #[inline]
227    fn from(value: Option<RustcVersion>) -> Self {
228        Self {
229            stack: SmallVec::from_iter(value),
230        }
231    }
232}
233
234impl MsrvStack {
235    pub fn current(&self) -> Option<RustcVersion> {
236        self.stack.last().copied()
237    }
238
239    pub fn meets(&self, required: RustcVersion) -> bool {
240        self.current().is_none_or(|msrv| msrv >= required)
241    }
242
243    pub fn check_attributes(&mut self, attrs: &[Attribute]) {
244        if let Some(version) = parse_attrs(attrs) {
245            SEEN_MSRV_ATTR.store(true, Ordering::Relaxed);
246            self.stack.push(version);
247        }
248    }
249
250    pub fn check_attributes_post(&mut self, attrs: &[Attribute]) {
251        if parse_attrs(attrs).is_some() {
252            self.stack.pop();
253        }
254    }
255}
256
257fn parse_attrs(attrs: &[impl AttributeExt]) -> Option<RustcVersion> {
258    let msrv_attr = attrs.iter().find(|attr| attr.path_matches(&[sym::clippy, sym::msrv]))?;
259
260    let msrv = msrv_attr.value_str()?;
261
262    parse_version(msrv)
263}
264
265pub fn check_attrs(sess: &Session, attrs: &[impl AttributeExt]) {
266    let mut msrv_attrs = attrs.iter().filter(|attr| attr.path_matches(&[sym::clippy, sym::msrv]));
267
268    let Some(msrv_attr) = msrv_attrs.next() else {
269        return;
270    };
271
272    if let Some(duplicate) = msrv_attrs.next_back() {
273        sess.dcx()
274            .struct_span_err(duplicate.span(), "`clippy::msrv` is defined multiple times")
275            .with_span_note(msrv_attr.span(), "first definition found here")
276            .emit();
277    }
278
279    let Some(msrv) = msrv_attr.value_str() else {
280        sess.dcx().span_err(msrv_attr.span(), "bad clippy attribute");
281        return;
282    };
283
284    if parse_version(msrv).is_none() {
285        sess.dcx()
286            .span_err(msrv_attr.span(), format!("`{msrv}` is not a valid Rust version"));
287    }
288}
clippy_utils/msrvs.rs

clippy_utils/
msrvs.rs
