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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_lint/src/enum_intrinsics_non_enums.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_lint/src/enum_intrinsics_non_enums.rs')
-rw-r--r-- | compiler/rustc_lint/src/enum_intrinsics_non_enums.rs | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/compiler/rustc_lint/src/enum_intrinsics_non_enums.rs b/compiler/rustc_lint/src/enum_intrinsics_non_enums.rs new file mode 100644 index 000000000..f41ee6404 --- /dev/null +++ b/compiler/rustc_lint/src/enum_intrinsics_non_enums.rs @@ -0,0 +1,88 @@ +use crate::{context::LintContext, LateContext, LateLintPass}; +use rustc_errors::fluent; +use rustc_hir as hir; +use rustc_middle::ty::{visit::TypeVisitable, Ty}; +use rustc_span::{symbol::sym, Span}; + +declare_lint! { + /// The `enum_intrinsics_non_enums` lint detects calls to + /// intrinsic functions that require an enum ([`core::mem::discriminant`], + /// [`core::mem::variant_count`]), but are called with a non-enum type. + /// + /// [`core::mem::discriminant`]: https://doc.rust-lang.org/core/mem/fn.discriminant.html + /// [`core::mem::variant_count`]: https://doc.rust-lang.org/core/mem/fn.variant_count.html + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(enum_intrinsics_non_enums)] + /// core::mem::discriminant::<i32>(&123); + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// In order to accept any enum, the `mem::discriminant` and + /// `mem::variant_count` functions are generic over a type `T`. + /// This makes it technically possible for `T` to be a non-enum, + /// in which case the return value is unspecified. + /// + /// This lint prevents such incorrect usage of these functions. + ENUM_INTRINSICS_NON_ENUMS, + Deny, + "detects calls to `core::mem::discriminant` and `core::mem::variant_count` with non-enum types" +} + +declare_lint_pass!(EnumIntrinsicsNonEnums => [ENUM_INTRINSICS_NON_ENUMS]); + +/// Returns `true` if we know for sure that the given type is not an enum. Note that for cases where +/// the type is generic, we can't be certain if it will be an enum so we have to assume that it is. +fn is_non_enum(t: Ty<'_>) -> bool { + !t.is_enum() && !t.needs_subst() +} + +fn enforce_mem_discriminant( + cx: &LateContext<'_>, + func_expr: &hir::Expr<'_>, + expr_span: Span, + args_span: Span, +) { + let ty_param = cx.typeck_results().node_substs(func_expr.hir_id).type_at(0); + if is_non_enum(ty_param) { + cx.struct_span_lint(ENUM_INTRINSICS_NON_ENUMS, expr_span, |builder| { + builder + .build(fluent::lint::enum_intrinsics_mem_discriminant) + .set_arg("ty_param", ty_param) + .span_note(args_span, fluent::lint::note) + .emit(); + }); + } +} + +fn enforce_mem_variant_count(cx: &LateContext<'_>, func_expr: &hir::Expr<'_>, span: Span) { + let ty_param = cx.typeck_results().node_substs(func_expr.hir_id).type_at(0); + if is_non_enum(ty_param) { + cx.struct_span_lint(ENUM_INTRINSICS_NON_ENUMS, span, |builder| { + builder + .build(fluent::lint::enum_intrinsics_mem_variant) + .set_arg("ty_param", ty_param) + .note(fluent::lint::note) + .emit(); + }); + } +} + +impl<'tcx> LateLintPass<'tcx> for EnumIntrinsicsNonEnums { + fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) { + let hir::ExprKind::Call(func, args) = &expr.kind else { return }; + let hir::ExprKind::Path(qpath) = &func.kind else { return }; + let Some(def_id) = cx.qpath_res(qpath, func.hir_id).opt_def_id() else { return }; + let Some(name) = cx.tcx.get_diagnostic_name(def_id) else { return }; + match name { + sym::mem_discriminant => enforce_mem_discriminant(cx, func, expr.span, args[0].span), + sym::mem_variant_count => enforce_mem_variant_count(cx, func, expr.span), + _ => {} + } + } +} |