diff --git a/compiler/rustc_lint/src/drop_forget_useless.rs b/compiler/rustc_lint/src/drop_forget_useless.rs index 7f098893f7de5..c2d137986ce4d 100644 --- a/compiler/rustc_lint/src/drop_forget_useless.rs +++ b/compiler/rustc_lint/src/drop_forget_useless.rs @@ -151,7 +151,7 @@ impl<'tcx> LateLintPass<'tcx> for DropForgetUseless { && let Node::Stmt(stmt) = node && let StmtKind::Semi(e) = stmt.kind && e.hir_id == expr.hir_id - && let Some(arg_span) = arg.span.find_ancestor_inside(expr.span) + && let Some(arg_span) = arg.span.find_ancestor_inside_same_ctxt(expr.span) { UseLetUnderscoreIgnoreSuggestion::Suggestion { start_span: expr.span.shrink_to_lo().until(arg_span), diff --git a/tests/ui/lint/dropping_copy_types-macros.fixed b/tests/ui/lint/dropping_copy_types-macros.fixed index a8ceedadc8063..2a0c398815755 100644 --- a/tests/ui/lint/dropping_copy_types-macros.fixed +++ b/tests/ui/lint/dropping_copy_types-macros.fixed @@ -9,4 +9,7 @@ fn main() { let mut msg = String::new(); let _ = writeln!(&mut msg, "test"); //~^ ERROR calls to `std::mem::drop` + + let _ = format_args!("a"); + //~^ ERROR calls to `std::mem::drop` } diff --git a/tests/ui/lint/dropping_copy_types-macros.rs b/tests/ui/lint/dropping_copy_types-macros.rs index b249b0c868f37..2272e0e8560d1 100644 --- a/tests/ui/lint/dropping_copy_types-macros.rs +++ b/tests/ui/lint/dropping_copy_types-macros.rs @@ -9,4 +9,7 @@ fn main() { let mut msg = String::new(); drop(writeln!(&mut msg, "test")); //~^ ERROR calls to `std::mem::drop` + + drop(format_args!("a")); + //~^ ERROR calls to `std::mem::drop` } diff --git a/tests/ui/lint/dropping_copy_types-macros.stderr b/tests/ui/lint/dropping_copy_types-macros.stderr index 117e9f4fe099c..5048f6e3f18bf 100644 --- a/tests/ui/lint/dropping_copy_types-macros.stderr +++ b/tests/ui/lint/dropping_copy_types-macros.stderr @@ -17,5 +17,19 @@ LL - drop(writeln!(&mut msg, "test")); LL + let _ = writeln!(&mut msg, "test"); | -error: aborting due to 1 previous error +error: calls to `std::mem::drop` with a value that implements `Copy` does nothing + --> $DIR/dropping_copy_types-macros.rs:13:5 + | +LL | drop(format_args!("a")); + | ^^^^^-----------------^ + | | + | argument has type `Arguments<'_>` + | +help: use `let _ = ...` to ignore the expression or result + | +LL - drop(format_args!("a")); +LL + let _ = format_args!("a"); + | + +error: aborting due to 2 previous errors