diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl index a9304f27fe557..21c7c5bb8b217 100644 --- a/compiler/rustc_lint/messages.ftl +++ b/compiler/rustc_lint/messages.ftl @@ -233,6 +233,7 @@ lint_drop_trait_constraints = lint_dropping_copy_types = calls to `std::mem::drop` with a value that implements `Copy` does nothing .label = argument has type `{$arg_ty}` .note = use `let _ = ...` to ignore the expression or result + .suggestion = use `let _ = ...` to ignore the expression or result lint_dropping_references = calls to `std::mem::drop` with a reference instead of an owned value does nothing .label = argument has type `{$arg_ty}` diff --git a/compiler/rustc_lint/src/drop_forget_useless.rs b/compiler/rustc_lint/src/drop_forget_useless.rs index 60b799f3c7468..02d324520b859 100644 --- a/compiler/rustc_lint/src/drop_forget_useless.rs +++ b/compiler/rustc_lint/src/drop_forget_useless.rs @@ -1,12 +1,12 @@ -use rustc_hir::{Arm, Expr, ExprKind, Node}; +use rustc_hir::{Arm, Expr, ExprKind, Node, StmtKind}; use rustc_middle::ty; use rustc_session::{declare_lint, declare_lint_pass}; use rustc_span::sym; use crate::{ lints::{ - DropCopyDiag, DropRefDiag, ForgetCopyDiag, ForgetRefDiag, UndroppedManuallyDropsDiag, - UndroppedManuallyDropsSuggestion, + DropCopyDiag, DropCopySuggestion, DropRefDiag, ForgetCopyDiag, ForgetRefDiag, + UndroppedManuallyDropsDiag, UndroppedManuallyDropsSuggestion, }, LateContext, LateLintPass, LintContext, }; @@ -164,10 +164,23 @@ impl<'tcx> LateLintPass<'tcx> for DropForgetUseless { ); } sym::mem_drop if is_copy && !drop_is_single_call_in_arm => { + let sugg = if let Some((_, node)) = cx.tcx.hir().parent_iter(expr.hir_id).nth(0) + && let Node::Stmt(stmt) = node + && let StmtKind::Semi(e) = stmt.kind + && e.hir_id == expr.hir_id + { + DropCopySuggestion::Suggestion { + start_span: expr.span.shrink_to_lo().until(arg.span), + end_span: arg.span.shrink_to_hi().until(expr.span.shrink_to_hi()), + } + } else { + DropCopySuggestion::Note + }; + cx.emit_span_lint( DROPPING_COPY_TYPES, expr.span, - DropCopyDiag { arg_ty, label: arg.span }, + DropCopyDiag { arg_ty, label: arg.span, sugg }, ); } sym::mem_forget if is_copy => { diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs index 2f44bc4764e33..87ca1ccd104e3 100644 --- a/compiler/rustc_lint/src/lints.rs +++ b/compiler/rustc_lint/src/lints.rs @@ -677,11 +677,25 @@ pub struct DropRefDiag<'a> { #[derive(LintDiagnostic)] #[diag(lint_dropping_copy_types)] -#[note] pub struct DropCopyDiag<'a> { pub arg_ty: Ty<'a>, #[label] pub label: Span, + #[subdiagnostic] + pub sugg: DropCopySuggestion, +} + +#[derive(Subdiagnostic)] +pub enum DropCopySuggestion { + #[note(lint_note)] + Note, + #[multipart_suggestion(lint_suggestion, style = "verbose", applicability = "maybe-incorrect")] + Suggestion { + #[suggestion_part(code = "let _ = ")] + start_span: Span, + #[suggestion_part(code = "")] + end_span: Span, + }, } #[derive(LintDiagnostic)] diff --git a/tests/ui/associated-types/defaults-unsound-62211-1.next.stderr b/tests/ui/associated-types/defaults-unsound-62211-1.next.stderr index 834ae00a8d85b..ffb02eccc77dc 100644 --- a/tests/ui/associated-types/defaults-unsound-62211-1.next.stderr +++ b/tests/ui/associated-types/defaults-unsound-62211-1.next.stderr @@ -6,8 +6,12 @@ LL | drop(origin); | | | argument has type `::Output` | - = note: use `let _ = ...` to ignore the expression or result = note: `#[warn(dropping_copy_types)]` on by default +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(origin); +LL + let _ = origin; + | warning: 1 warning emitted diff --git a/tests/ui/associated-types/defaults-unsound-62211-2.next.stderr b/tests/ui/associated-types/defaults-unsound-62211-2.next.stderr index 0f944a18ed58b..e6ae8183e77dc 100644 --- a/tests/ui/associated-types/defaults-unsound-62211-2.next.stderr +++ b/tests/ui/associated-types/defaults-unsound-62211-2.next.stderr @@ -6,8 +6,12 @@ LL | drop(origin); | | | argument has type `::Output` | - = note: use `let _ = ...` to ignore the expression or result = note: `#[warn(dropping_copy_types)]` on by default +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(origin); +LL + let _ = origin; + | warning: 1 warning emitted diff --git a/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.rs b/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.rs new file mode 100644 index 0000000000000..12c984c932acf --- /dev/null +++ b/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.rs @@ -0,0 +1,14 @@ +//@ check-fail + +#![deny(dropping_copy_types)] + +fn main() { + let y = 1; + let z = 2; + match y { + 0 => drop(y), //~ ERROR calls to `std::mem::drop` + 1 => drop(z), //~ ERROR calls to `std::mem::drop` + 2 => drop(3), //~ ERROR calls to `std::mem::drop` + _ => {}, + } +} diff --git a/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.stderr b/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.stderr new file mode 100644 index 0000000000000..6c73e5ea90b47 --- /dev/null +++ b/tests/ui/lint/dropping_copy_types-issue-125189-can-not-fixed.stderr @@ -0,0 +1,37 @@ +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-issue-125189-can-not-fixed.rs:9:14 + | +LL | 0 => drop(y), + | ^^^^^-^ + | | + | argument has type `i32` + | + = note: use `let _ = ...` to ignore the expression or result +note: the lint level is defined here + --> $DIR/dropping_copy_types-issue-125189-can-not-fixed.rs:3:9 + | +LL | #![deny(dropping_copy_types)] + | ^^^^^^^^^^^^^^^^^^^ + +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-issue-125189-can-not-fixed.rs:10:14 + | +LL | 1 => drop(z), + | ^^^^^-^ + | | + | argument has type `i32` + | + = note: use `let _ = ...` to ignore the expression or result + +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-issue-125189-can-not-fixed.rs:11:14 + | +LL | 2 => drop(3), + | ^^^^^-^ + | | + | argument has type `i32` + | + = note: use `let _ = ...` to ignore the expression or result + +error: aborting due to 3 previous errors + diff --git a/tests/ui/lint/dropping_copy_types-issue-125189.fixed b/tests/ui/lint/dropping_copy_types-issue-125189.fixed new file mode 100644 index 0000000000000..2dfd68d4cc16a --- /dev/null +++ b/tests/ui/lint/dropping_copy_types-issue-125189.fixed @@ -0,0 +1,10 @@ +//@ check-fail +//@ run-rustfix + +#![deny(dropping_copy_types)] + +fn main() { + let y = 1; + let _ = 3.2; //~ ERROR calls to `std::mem::drop` + let _ = y; //~ ERROR calls to `std::mem::drop` +} diff --git a/tests/ui/lint/dropping_copy_types-issue-125189.rs b/tests/ui/lint/dropping_copy_types-issue-125189.rs new file mode 100644 index 0000000000000..1f42efabba9ff --- /dev/null +++ b/tests/ui/lint/dropping_copy_types-issue-125189.rs @@ -0,0 +1,10 @@ +//@ check-fail +//@ run-rustfix + +#![deny(dropping_copy_types)] + +fn main() { + let y = 1; + drop(3.2); //~ ERROR calls to `std::mem::drop` + drop(y); //~ ERROR calls to `std::mem::drop` +} diff --git a/tests/ui/lint/dropping_copy_types-issue-125189.stderr b/tests/ui/lint/dropping_copy_types-issue-125189.stderr new file mode 100644 index 0000000000000..ba3e36f5b6ec4 --- /dev/null +++ b/tests/ui/lint/dropping_copy_types-issue-125189.stderr @@ -0,0 +1,35 @@ +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-issue-125189.rs:8:5 + | +LL | drop(3.2); + | ^^^^^---^ + | | + | argument has type `f64` + | +note: the lint level is defined here + --> $DIR/dropping_copy_types-issue-125189.rs:4:9 + | +LL | #![deny(dropping_copy_types)] + | ^^^^^^^^^^^^^^^^^^^ +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(3.2); +LL + let _ = 3.2; + | + +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-issue-125189.rs:9:5 + | +LL | drop(y); + | ^^^^^-^ + | | + | argument has type `i32` + | +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(y); +LL + let _ = y; + | + +error: aborting due to 2 previous errors + diff --git a/tests/ui/lint/dropping_copy_types.stderr b/tests/ui/lint/dropping_copy_types.stderr index b6291aa5ed634..bdeb0c290fe93 100644 --- a/tests/ui/lint/dropping_copy_types.stderr +++ b/tests/ui/lint/dropping_copy_types.stderr @@ -6,12 +6,16 @@ LL | drop(s1); | | | argument has type `SomeStruct` | - = note: use `let _ = ...` to ignore the expression or result note: the lint level is defined here --> $DIR/dropping_copy_types.rs:3:9 | LL | #![warn(dropping_copy_types)] | ^^^^^^^^^^^^^^^^^^^ +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(s1); +LL + let _ = s1; + | warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing --> $DIR/dropping_copy_types.rs:35:5 @@ -21,7 +25,11 @@ LL | drop(s2); | | | argument has type `SomeStruct` | - = note: use `let _ = ...` to ignore the expression or result +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(s2); +LL + let _ = s2; + | warning: calls to `std::mem::drop` with a reference instead of an owned value does nothing --> $DIR/dropping_copy_types.rs:36:5 @@ -42,7 +50,11 @@ LL | drop(s4); | | | argument has type `SomeStruct` | - = note: use `let _ = ...` to ignore the expression or result +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(s4); +LL + let _ = s4; + | warning: calls to `std::mem::drop` with a reference instead of an owned value does nothing --> $DIR/dropping_copy_types.rs:38:5 @@ -82,7 +94,11 @@ LL | drop(println_and(13)); | | | argument has type `i32` | - = note: use `let _ = ...` to ignore the expression or result +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(println_and(13)); +LL + let _ = println_and(13); + | warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing --> $DIR/dropping_copy_types.rs:74:14