diff options
Diffstat (limited to 'clippy_utils/src')
| -rw-r--r-- | clippy_utils/src/consts.rs | 107 | ||||
| -rw-r--r-- | clippy_utils/src/diagnostics.rs | 118 | ||||
| -rw-r--r-- | clippy_utils/src/lib.rs | 19 | ||||
| -rw-r--r-- | clippy_utils/src/paths.rs | 2 | ||||
| -rw-r--r-- | clippy_utils/src/source.rs | 2 |
5 files changed, 237 insertions, 11 deletions
diff --git a/clippy_utils/src/consts.rs b/clippy_utils/src/consts.rs index e75d5953fae..046087d3298 100644 --- a/clippy_utils/src/consts.rs +++ b/clippy_utils/src/consts.rs @@ -10,8 +10,10 @@ use rustc_hir::{BinOp, BinOpKind, Block, ConstBlock, Expr, ExprKind, HirId, Item use rustc_lexer::tokenize; use rustc_lint::LateContext; use rustc_middle::mir::interpret::{alloc_range, Scalar}; +use rustc_middle::mir::ConstValue; use rustc_middle::ty::{self, EarlyBinder, FloatTy, GenericArgsRef, IntTy, List, ScalarInt, Ty, TyCtxt, UintTy}; use rustc_middle::{bug, mir, span_bug}; +use rustc_span::def_id::DefId; use rustc_span::symbol::{Ident, Symbol}; use rustc_span::SyntaxContext; use rustc_target::abi::Size; @@ -307,6 +309,12 @@ impl ConstantSource { } } +/// Attempts to check whether the expression is a constant representing an empty slice, str, array, +/// etc… +pub fn constant_is_empty(lcx: &LateContext<'_>, e: &Expr<'_>) -> Option<bool> { + ConstEvalLateContext::new(lcx, lcx.typeck_results()).expr_is_empty(e) +} + /// Attempts to evaluate the expression as a constant. pub fn constant<'tcx>( lcx: &LateContext<'tcx>, @@ -406,7 +414,13 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> { match e.kind { ExprKind::ConstBlock(ConstBlock { body, .. }) => self.expr(self.lcx.tcx.hir().body(body).value), ExprKind::DropTemps(e) => self.expr(e), - ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id, self.typeck_results.expr_ty(e)), + ExprKind::Path(ref qpath) => { + self.fetch_path_and_apply(qpath, e.hir_id, self.typeck_results.expr_ty(e), |this, result| { + let result = mir_to_const(this.lcx, result)?; + this.source = ConstantSource::Constant; + Some(result) + }) + }, ExprKind::Block(block, _) => self.block(block), ExprKind::Lit(lit) => { if is_direct_expn_of(e.span, "cfg").is_some() { @@ -472,6 +486,49 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> { } } + /// Simple constant folding to determine if an expression is an empty slice, str, array, … + /// `None` will be returned if the constness cannot be determined, or if the resolution + /// leaves the local crate. + pub fn expr_is_empty(&mut self, e: &Expr<'_>) -> Option<bool> { + match e.kind { + ExprKind::ConstBlock(ConstBlock { body, .. }) => self.expr_is_empty(self.lcx.tcx.hir().body(body).value), + ExprKind::DropTemps(e) => self.expr_is_empty(e), + ExprKind::Path(ref qpath) => { + if !self + .typeck_results + .qpath_res(qpath, e.hir_id) + .opt_def_id() + .is_some_and(DefId::is_local) + { + return None; + } + self.fetch_path_and_apply(qpath, e.hir_id, self.typeck_results.expr_ty(e), |this, result| { + mir_is_empty(this.lcx, result) + }) + }, + ExprKind::Lit(lit) => { + if is_direct_expn_of(e.span, "cfg").is_some() { + None + } else { + match &lit.node { + LitKind::Str(is, _) => Some(is.is_empty()), + LitKind::ByteStr(s, _) | LitKind::CStr(s, _) => Some(s.is_empty()), + _ => None, + } + } + }, + ExprKind::Array(vec) => self.multi(vec).map(|v| v.is_empty()), + ExprKind::Repeat(..) => { + if let ty::Array(_, n) = self.typeck_results.expr_ty(e).kind() { + Some(n.try_eval_target_usize(self.lcx.tcx, self.lcx.param_env)? == 0) + } else { + span_bug!(e.span, "typeck error"); + } + }, + _ => None, + } + } + #[expect(clippy::cast_possible_wrap)] fn constant_not(&self, o: &Constant<'tcx>, ty: Ty<'_>) -> Option<Constant<'tcx>> { use self::Constant::{Bool, Int}; @@ -519,8 +576,11 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> { vec.iter().map(|elem| self.expr(elem)).collect::<Option<_>>() } - /// Lookup a possibly constant expression from an `ExprKind::Path`. - fn fetch_path(&mut self, qpath: &QPath<'_>, id: HirId, ty: Ty<'tcx>) -> Option<Constant<'tcx>> { + /// Lookup a possibly constant expression from an `ExprKind::Path` and apply a function on it. + fn fetch_path_and_apply<T, F>(&mut self, qpath: &QPath<'_>, id: HirId, ty: Ty<'tcx>, f: F) -> Option<T> + where + F: FnOnce(&mut Self, rustc_middle::mir::Const<'tcx>) -> Option<T>, + { let res = self.typeck_results.qpath_res(qpath, id); match res { Res::Def(DefKind::Const | DefKind::AssocConst, def_id) => { @@ -553,9 +613,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> { .const_eval_resolve(self.param_env, mir::UnevaluatedConst::new(def_id, args), qpath.span()) .ok() .map(|val| rustc_middle::mir::Const::from_value(val, ty))?; - let result = mir_to_const(self.lcx, result)?; - self.source = ConstantSource::Constant; - Some(result) + f(self, result) }, _ => None, } @@ -746,7 +804,6 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> { } pub fn mir_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) -> Option<Constant<'tcx>> { - use rustc_middle::mir::ConstValue; let mir::Const::Val(val, _) = result else { // We only work on evaluated consts. return None; @@ -794,6 +851,42 @@ pub fn mir_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) -> } } +fn mir_is_empty<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) -> Option<bool> { + let mir::Const::Val(val, _) = result else { + // We only work on evaluated consts. + return None; + }; + match (val, result.ty().kind()) { + (_, ty::Ref(_, inner_ty, _)) => match inner_ty.kind() { + ty::Str | ty::Slice(_) => { + if let ConstValue::Indirect { alloc_id, offset } = val { + // Get the length from the slice, using the same formula as + // [`ConstValue::try_get_slice_bytes_for_diagnostics`]. + let a = lcx.tcx.global_alloc(alloc_id).unwrap_memory().inner(); + let ptr_size = lcx.tcx.data_layout.pointer_size; + if a.size() < offset + 2 * ptr_size { + // (partially) dangling reference + return None; + } + let len = a + .read_scalar(&lcx.tcx, alloc_range(offset + ptr_size, ptr_size), false) + .ok()? + .to_target_usize(&lcx.tcx) + .ok()?; + Some(len == 0) + } else { + None + } + }, + ty::Array(_, len) => Some(len.try_to_target_usize(lcx.tcx)? == 0), + _ => None, + }, + (ConstValue::Indirect { .. }, ty::Array(_, len)) => Some(len.try_to_target_usize(lcx.tcx)? == 0), + (ConstValue::ZeroSized, _) => Some(true), + _ => None, + } +} + fn field_of_struct<'tcx>( adt_def: ty::AdtDef<'tcx>, lcx: &LateContext<'tcx>, diff --git a/clippy_utils/src/diagnostics.rs b/clippy_utils/src/diagnostics.rs index 6ed46e5dde0..0352696f93e 100644 --- a/clippy_utils/src/diagnostics.rs +++ b/clippy_utils/src/diagnostics.rs @@ -36,6 +36,20 @@ fn docs_link(diag: &mut Diag<'_, ()>, lint: &'static Lint) { /// Usually it's nicer to provide more context for lint messages. /// Be sure the output is understandable when you use this method. /// +/// NOTE: Lint emissions are always bound to a node in the HIR, which is used to determine +/// the lint level. +/// For the `span_lint` function, the node that was passed into the `LintPass::check_*` function is +/// used. +/// +/// If you're emitting the lint at the span of a different node than the one provided by the +/// `LintPass::check_*` function, consider using [`span_lint_hir`] instead. +/// This is needed for `#[allow]` and `#[expect]` attributes to work on the node +/// highlighted in the displayed warning. +/// +/// If you're unsure which function you should use, you can test if the `#[allow]` attribute works +/// where you would expect it to. +/// If it doesn't, you likely need to use [`span_lint_hir`] instead. +/// /// # Example /// /// ```ignore @@ -61,6 +75,20 @@ pub fn span_lint<T: LintContext>(cx: &T, lint: &'static Lint, sp: impl Into<Mult /// /// If you change the signature, remember to update the internal lint `CollapsibleCalls` /// +/// NOTE: Lint emissions are always bound to a node in the HIR, which is used to determine +/// the lint level. +/// For the `span_lint_and_help` function, the node that was passed into the `LintPass::check_*` +/// function is used. +/// +/// If you're emitting the lint at the span of a different node than the one provided by the +/// `LintPass::check_*` function, consider using [`span_lint_hir_and_then`] instead. +/// This is needed for `#[allow]` and `#[expect]` attributes to work on the node +/// highlighted in the displayed warning. +/// +/// If you're unsure which function you should use, you can test if the `#[allow]` attribute works +/// where you would expect it to. +/// If it doesn't, you likely need to use [`span_lint_hir_and_then`] instead. +/// /// # Example /// /// ```text @@ -99,6 +127,20 @@ pub fn span_lint_and_help<T: LintContext>( /// /// If you change the signature, remember to update the internal lint `CollapsibleCalls` /// +/// NOTE: Lint emissions are always bound to a node in the HIR, which is used to determine +/// the lint level. +/// For the `span_lint_and_note` function, the node that was passed into the `LintPass::check_*` +/// function is used. +/// +/// If you're emitting the lint at the span of a different node than the one provided by the +/// `LintPass::check_*` function, consider using [`span_lint_hir_and_then`] instead. +/// This is needed for `#[allow]` and `#[expect]` attributes to work on the node +/// highlighted in the displayed warning. +/// +/// If you're unsure which function you should use, you can test if the `#[allow]` attribute works +/// where you would expect it to. +/// If it doesn't, you likely need to use [`span_lint_hir_and_then`] instead. +/// /// # Example /// /// ```text @@ -139,6 +181,20 @@ pub fn span_lint_and_note<T: LintContext>( /// /// If you need to customize your lint output a lot, use this function. /// If you change the signature, remember to update the internal lint `CollapsibleCalls` +/// +/// NOTE: Lint emissions are always bound to a node in the HIR, which is used to determine +/// the lint level. +/// For the `span_lint_and_then` function, the node that was passed into the `LintPass::check_*` +/// function is used. +/// +/// If you're emitting the lint at the span of a different node than the one provided by the +/// `LintPass::check_*` function, consider using [`span_lint_hir_and_then`] instead. +/// This is needed for `#[allow]` and `#[expect]` attributes to work on the node +/// highlighted in the displayed warning. +/// +/// If you're unsure which function you should use, you can test if the `#[allow]` attribute works +/// where you would expect it to. +/// If it doesn't, you likely need to use [`span_lint_hir_and_then`] instead. pub fn span_lint_and_then<C, S, F>(cx: &C, lint: &'static Lint, sp: S, msg: &str, f: F) where C: LintContext, @@ -152,6 +208,30 @@ where }); } +/// Like [`span_lint`], but emits the lint at the node identified by the given `HirId`. +/// +/// This is in contrast to [`span_lint`], which always emits the lint at the node that was last +/// passed to the `LintPass::check_*` function. +/// +/// The `HirId` is used for checking lint level attributes and to fulfill lint expectations defined +/// via the `#[expect]` attribute. +/// +/// For example: +/// ```ignore +/// fn f() { /* <node_1> */ +/// +/// #[allow(clippy::some_lint)] +/// let _x = /* <expr_1> */; +/// } +/// ``` +/// If `some_lint` does its analysis in `LintPass::check_fn` (at `<node_1>`) and emits a lint at +/// `<expr_1>` using [`span_lint`], then allowing the lint at `<expr_1>` as attempted in the snippet +/// will not work! +/// Even though that is where the warning points at, which would be confusing to users. +/// +/// Instead, use this function and also pass the `HirId` of `<expr_1>`, which will let +/// the compiler check lint level attributes at the place of the expression and +/// the `#[allow]` will work. pub fn span_lint_hir(cx: &LateContext<'_>, lint: &'static Lint, hir_id: HirId, sp: Span, msg: &str) { #[expect(clippy::disallowed_methods)] cx.tcx.node_span_lint(lint, hir_id, sp, msg.to_string(), |diag| { @@ -159,6 +239,30 @@ pub fn span_lint_hir(cx: &LateContext<'_>, lint: &'static Lint, hir_id: HirId, s }); } +/// Like [`span_lint_and_then`], but emits the lint at the node identified by the given `HirId`. +/// +/// This is in contrast to [`span_lint_and_then`], which always emits the lint at the node that was +/// last passed to the `LintPass::check_*` function. +/// +/// The `HirId` is used for checking lint level attributes and to fulfill lint expectations defined +/// via the `#[expect]` attribute. +/// +/// For example: +/// ```ignore +/// fn f() { /* <node_1> */ +/// +/// #[allow(clippy::some_lint)] +/// let _x = /* <expr_1> */; +/// } +/// ``` +/// If `some_lint` does its analysis in `LintPass::check_fn` (at `<node_1>`) and emits a lint at +/// `<expr_1>` using [`span_lint`], then allowing the lint at `<expr_1>` as attempted in the snippet +/// will not work! +/// Even though that is where the warning points at, which would be confusing to users. +/// +/// Instead, use this function and also pass the `HirId` of `<expr_1>`, which will let +/// the compiler check lint level attributes at the place of the expression and +/// the `#[allow]` will work. pub fn span_lint_hir_and_then( cx: &LateContext<'_>, lint: &'static Lint, @@ -182,6 +286,20 @@ pub fn span_lint_hir_and_then( /// /// If you change the signature, remember to update the internal lint `CollapsibleCalls` /// +/// NOTE: Lint emissions are always bound to a node in the HIR, which is used to determine +/// the lint level. +/// For the `span_lint_and_sugg` function, the node that was passed into the `LintPass::check_*` +/// function is used. +/// +/// If you're emitting the lint at the span of a different node than the one provided by the +/// `LintPass::check_*` function, consider using [`span_lint_hir_and_then`] instead. +/// This is needed for `#[allow]` and `#[expect]` attributes to work on the node +/// highlighted in the displayed warning. +/// +/// If you're unsure which function you should use, you can test if the `#[allow]` attribute works +/// where you would expect it to. +/// If it doesn't, you likely need to use [`span_lint_hir_and_then`] instead. +/// /// # Example /// /// ```text diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index a38db0ebec0..d040fb28c63 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -2246,8 +2246,21 @@ pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool { /// Returns the `DefId` of the callee if the given expression is a function or method call. pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> { + fn_def_id_with_node_args(cx, expr).map(|(did, _)| did) +} + +/// Returns the `DefId` of the callee if the given expression is a function or method call, +/// as well as its node args. +pub fn fn_def_id_with_node_args<'tcx>( + cx: &LateContext<'tcx>, + expr: &Expr<'_>, +) -> Option<(DefId, rustc_ty::GenericArgsRef<'tcx>)> { + let typeck = cx.typeck_results(); match &expr.kind { - ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id), + ExprKind::MethodCall(..) => Some(( + typeck.type_dependent_def_id(expr.hir_id)?, + typeck.node_args(expr.hir_id), + )), ExprKind::Call( Expr { kind: ExprKind::Path(qpath), @@ -2259,9 +2272,9 @@ pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> { // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or // deref to fn pointers, dyn Fn, impl Fn - #8850 if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) = - cx.typeck_results().qpath_res(qpath, *path_hir_id) + typeck.qpath_res(qpath, *path_hir_id) { - Some(id) + Some((id, typeck.node_args(*path_hir_id))) } else { None } diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs index 987f28192a8..456b8019e95 100644 --- a/clippy_utils/src/paths.rs +++ b/clippy_utils/src/paths.rs @@ -19,6 +19,8 @@ pub const BTREESET_ITER: [&str; 6] = ["alloc", "collections", "btree", "set", "B pub const CLONE_TRAIT_METHOD: [&str; 4] = ["core", "clone", "Clone", "clone"]; pub const CORE_ITER_CLONED: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "cloned"]; pub const CORE_ITER_COPIED: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "copied"]; +pub const CORE_ITER_ENUMERATE_METHOD: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "enumerate"]; +pub const CORE_ITER_ENUMERATE_STRUCT: [&str; 5] = ["core", "iter", "adapters", "enumerate", "Enumerate"]; pub const CORE_ITER_FILTER: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "filter"]; pub const CORE_RESULT_OK_METHOD: [&str; 4] = ["core", "result", "Result", "ok"]; pub const CSTRING_AS_C_STR: [&str; 5] = ["alloc", "ffi", "c_str", "CString", "as_c_str"]; diff --git a/clippy_utils/src/source.rs b/clippy_utils/src/source.rs index e72467edeeb..a4a6f8e15f9 100644 --- a/clippy_utils/src/source.rs +++ b/clippy_utils/src/source.rs @@ -8,7 +8,7 @@ use rustc_hir::{BlockCheckMode, Expr, ExprKind, UnsafeSource}; use rustc_lint::{LateContext, LintContext}; use rustc_session::Session; use rustc_span::source_map::{original_sp, SourceMap}; -use rustc_span::{hygiene, BytePos, SourceFileAndLine, Pos, SourceFile, Span, SpanData, SyntaxContext, DUMMY_SP}; +use rustc_span::{hygiene, BytePos, Pos, SourceFile, SourceFileAndLine, Span, SpanData, SyntaxContext, DUMMY_SP}; use std::borrow::Cow; use std::ops::Range; |