diff --git a/clippy_lints/src/transmute/missing_transmute_annotations.rs b/clippy_lints/src/transmute/missing_transmute_annotations.rs index 08f36a2ed5d2..543f3c45e146 100644 --- a/clippy_lints/src/transmute/missing_transmute_annotations.rs +++ b/clippy_lints/src/transmute/missing_transmute_annotations.rs @@ -1,8 +1,12 @@ -use clippy_utils::diagnostics::span_lint_and_sugg; +use std::borrow::Cow; + +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::source::{HasSession, SpanRangeExt as _}; use rustc_errors::Applicability; -use rustc_hir::{GenericArg, HirId, LetStmt, Node, Path, TyKind}; +use rustc_hir::{Expr, GenericArg, HirId, LetStmt, Node, Path, TyKind}; use rustc_lint::LateContext; -use rustc_middle::ty::Ty; +use rustc_middle::ty::{self, Ty}; +use rustc_span::Span; use crate::transmute::MISSING_TRANSMUTE_ANNOTATIONS; @@ -38,6 +42,7 @@ fn is_function_block(cx: &LateContext<'_>, expr_hir_id: HirId) -> bool { pub(super) fn check<'tcx>( cx: &LateContext<'tcx>, path: &Path<'tcx>, + arg: &Expr<'tcx>, from_ty: Ty<'tcx>, to_ty: Ty<'tcx>, expr_hir_id: HirId, @@ -68,14 +73,48 @@ pub(super) fn check<'tcx>( } else if is_function_block(cx, expr_hir_id) { return false; } - span_lint_and_sugg( + let span = last.ident.span.with_hi(path.span.hi()); + span_lint_and_then( cx, MISSING_TRANSMUTE_ANNOTATIONS, - last.ident.span.with_hi(path.span.hi()), + span, "transmute used without annotations", - "consider adding missing annotations", - format!("{}::<{from_ty}, {to_ty}>", last.ident), - Applicability::MaybeIncorrect, + |diag| { + let from_ty_no_name = ty_cannot_be_named(from_ty); + let to_ty_no_name = ty_cannot_be_named(to_ty); + if from_ty_no_name || to_ty_no_name { + let to_name = match (from_ty_no_name, to_ty_no_name) { + (true, false) => maybe_name_by_expr(cx, arg.span, "the origin type"), + (false, true) => "the destination type".into(), + _ => "the source and destination types".into(), + }; + diag.help(format!( + "consider giving {to_name} a name, and adding missing type annotations" + )); + } else { + diag.span_suggestion( + span, + "consider adding missing annotations", + format!("{}::<{from_ty}, {to_ty}>", last.ident), + Applicability::MaybeIncorrect, + ); + } + }, ); true } + +fn ty_cannot_be_named(ty: Ty<'_>) -> bool { + matches!( + ty.kind(), + ty::Alias(ty::AliasTyKind::Opaque | ty::AliasTyKind::Inherent, _) + ) +} + +fn maybe_name_by_expr<'a>(sess: &impl HasSession, span: Span, default: &'a str) -> Cow<'a, str> { + span.with_source_text(sess, |name| { + (name.len() + 9 < default.len()).then_some(format!("`{name}`'s type").into()) + }) + .flatten() + .unwrap_or(default.into()) +} diff --git a/clippy_lints/src/transmute/mod.rs b/clippy_lints/src/transmute/mod.rs index d5112e2c3f97..284728b8ebbd 100644 --- a/clippy_lints/src/transmute/mod.rs +++ b/clippy_lints/src/transmute/mod.rs @@ -520,7 +520,7 @@ impl<'tcx> LateLintPass<'tcx> for Transmute { | transmuting_null::check(cx, e, arg, to_ty) | transmute_null_to_fn::check(cx, e, arg, to_ty) | transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, arg, path, self.msrv) - | missing_transmute_annotations::check(cx, path, from_ty, to_ty, e.hir_id) + | missing_transmute_annotations::check(cx, path, arg, from_ty, to_ty, e.hir_id) | transmute_ref_to_ref::check(cx, e, from_ty, to_ty, arg, const_context) | transmute_ptr_to_ptr::check(cx, e, from_ty, to_ty, arg, self.msrv) | transmute_int_to_bool::check(cx, e, from_ty, to_ty, arg) diff --git a/tests/ui/missing_transmute_annotations_unfixable.rs b/tests/ui/missing_transmute_annotations_unfixable.rs new file mode 100644 index 000000000000..08ba3b791ee7 --- /dev/null +++ b/tests/ui/missing_transmute_annotations_unfixable.rs @@ -0,0 +1,29 @@ +//@no-rustfix + +fn issue14984() { + async fn e() {} + async fn x() -> u32 { + 0 + } + async fn y() -> f32 { + 0.0 + }; + let mut yy = unsafe { std::ptr::read(&y()) }; + yy = unsafe { std::mem::transmute(std::ptr::read(&x())) }; + //~^ missing_transmute_annotations + + let mut zz = 0u8; + zz = unsafe { std::mem::transmute(std::ptr::read(&x())) }; + //~^ missing_transmute_annotations + + yy = unsafe { std::mem::transmute(zz) }; + //~^ missing_transmute_annotations + + fn a() -> impl Sized { + 0u32 + } + + let mut b: f32 = 0.0; + b = unsafe { std::mem::transmute(a()) }; + //~^ missing_transmute_annotations +} diff --git a/tests/ui/missing_transmute_annotations_unfixable.stderr b/tests/ui/missing_transmute_annotations_unfixable.stderr new file mode 100644 index 000000000000..83efdce13f7e --- /dev/null +++ b/tests/ui/missing_transmute_annotations_unfixable.stderr @@ -0,0 +1,36 @@ +error: transmute used without annotations + --> tests/ui/missing_transmute_annotations_unfixable.rs:12:29 + | +LL | yy = unsafe { std::mem::transmute(std::ptr::read(&x())) }; + | ^^^^^^^^^ + | + = help: consider giving the source and destination types a name, and adding missing type annotations + = note: `-D clippy::missing-transmute-annotations` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::missing_transmute_annotations)]` + +error: transmute used without annotations + --> tests/ui/missing_transmute_annotations_unfixable.rs:16:29 + | +LL | zz = unsafe { std::mem::transmute(std::ptr::read(&x())) }; + | ^^^^^^^^^ + | + = help: consider giving the origin type a name, and adding missing type annotations + +error: transmute used without annotations + --> tests/ui/missing_transmute_annotations_unfixable.rs:19:29 + | +LL | yy = unsafe { std::mem::transmute(zz) }; + | ^^^^^^^^^ + | + = help: consider giving the destination type a name, and adding missing type annotations + +error: transmute used without annotations + --> tests/ui/missing_transmute_annotations_unfixable.rs:27:28 + | +LL | b = unsafe { std::mem::transmute(a()) }; + | ^^^^^^^^^ + | + = help: consider giving `a()`'s type a name, and adding missing type annotations + +error: aborting due to 4 previous errors +