Tweak span for #[must_use]

Do not point at whole statement, only at the expression (skip pointing at `;`)

Author: estebank

compiler/rustc_lint/src/unused.rs

@@ -87,17 +87,14 @@ declare_lint_pass!(UnusedResults => [UNUSED_MUST_USE, UNUSED_RESULTS]);
 
 impl<'tcx> LateLintPass<'tcx> for UnusedResults {
     fn check_stmt(&mut self, cx: &LateContext<'_>, s: &hir::Stmt<'_>) {
-        let expr = match s.kind {
-            hir::StmtKind::Semi(ref expr) => &**expr,
-            _ => return,
-        };
+        let hir::StmtKind::Semi(expr) = s.kind else { return; };
 
         if let hir::ExprKind::Ret(..) = expr.kind {
             return;
         }
 
         let ty = cx.typeck_results().expr_ty(&expr);
-        let type_permits_lack_of_use = check_must_use_ty(cx, ty, &expr, s.span, "", "", 1);
+        let type_permits_lack_of_use = check_must_use_ty(cx, ty, &expr, expr.span, "", "", 1);
 
         let mut fn_warned = false;
         let mut op_warned = false;
@@ -119,7 +116,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
             _ => None,
         };
         if let Some(def_id) = maybe_def_id {
-            fn_warned = check_must_use_def(cx, def_id, s.span, "return value of ", "");
+            fn_warned = check_must_use_def(cx, def_id, expr.span, "return value of ", "");
         } else if type_permits_lack_of_use {
             // We don't warn about unused unit or uninhabited types.
             // (See https://github.com/rust-lang/rust/issues/43806 for details.)

src/test/ui/closures/2229_closure_analysis/match/issue-87097.stderr

@@ -16,7 +16,7 @@ LL | /     || match out_ref {
 LL | |         Variant::A => (),
 LL | |         Variant::B => (),
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: closures are lazy and do nothing unless called
    = note: `#[warn(unused_must_use)]` on by default
@@ -28,7 +28,7 @@ LL | /     || match here.field {
 LL | |         Variant::A => (),
 LL | |         Variant::B => (),
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: closures are lazy and do nothing unless called
 

src/test/ui/conditional-compilation/cfg-attr-multi-true.stderr

@@ -28,7 +28,7 @@ warning: unused `MustUseDeprecated` that must be used
   --> $DIR/cfg-attr-multi-true.rs:19:5
    |
 LL |     MustUseDeprecated::new();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/cfg-attr-multi-true.rs:7:9

src/test/ui/generator/issue-52398.stderr

@@ -4,7 +4,7 @@ warning: unused generator that must be used
 LL | /     move || {
 LL | |         A.test(yield);
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default
@@ -16,7 +16,7 @@ LL | /     static move || {
 LL | |         yield *y.borrow();
 LL | |         return "Done";
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
 

src/test/ui/generator/issue-57084.stderr

@@ -7,7 +7,7 @@ LL | |         loop {
 LL | |             yield
 LL | |         }
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/match-bindings.stderr

@@ -8,7 +8,7 @@ LL | |                 match Enum::A(String::new()) {
 ...  |
 LL | |         }
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/reborrow-mut-upvar.stderr

@@ -8,7 +8,7 @@ LL | |             yield;
 ...  |
 LL | |         *bar = 2;
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/too-live-local-in-immovable-gen.stderr

@@ -8,7 +8,7 @@ LL | |             // and it should also find out that `a` is not live.
 ...  |
 LL | |             let _ = &a;
 LL | |         };
-   | |__________^
+   | |_________^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/yield-in-args-rev.stderr

@@ -5,7 +5,7 @@ LL | /     || {
 LL | |         let b = true;
 LL | |         foo(yield, &b);
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/yield-in-box.stderr

@@ -8,7 +8,7 @@ LL | |             let _t = box (&x, yield 0, &y);
 ...  |
 LL | |         }
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default