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

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

@@ -8,7 +8,7 @@ LL | |             // See https://github.com/rust-lang/rust/issues/52792
 ...  |
 LL | |         }
 LL | |     };
-   | |______^
+   | |_____^
    |
    = note: generators are lazy and do nothing unless resumed
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/generator/yield-subtype.stderr

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

src/test/ui/issues/issue-1460.stderr

@@ -2,7 +2,7 @@ warning: unused closure that must be used
   --> $DIR/issue-1460.rs:6:5
    |
 LL |     {|i: u32| if 1 == i { }};
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: closures are lazy and do nothing unless called
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/issues/issue-16256.stderr

@@ -2,7 +2,7 @@ warning: unused closure that must be used
   --> $DIR/issue-16256.rs:6:5
    |
 LL |     |c: u8| buf.push(c);
-   |     ^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^
    |
    = note: closures are lazy and do nothing unless called
    = note: `#[warn(unused_must_use)]` on by default

src/test/ui/lint/fn_must_use.stderr

@@ -2,7 +2,7 @@ warning: unused return value of `need_to_use_this_value` that must be used
   --> $DIR/fn_must_use.rs:55:5
    |
 LL |     need_to_use_this_value();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: it's important
 note: the lint level is defined here
@@ -15,33 +15,33 @@ warning: unused return value of `MyStruct::need_to_use_this_method_value` that m
   --> $DIR/fn_must_use.rs:60:5
    |
 LL |     m.need_to_use_this_method_value();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: unused return value of `EvenNature::is_even` that must be used
   --> $DIR/fn_must_use.rs:61:5
    |
 LL |     m.is_even(); // trait method!
-   |     ^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
    |
    = note: no side effects
 
 warning: unused return value of `MyStruct::need_to_use_this_associated_function_value` that must be used
   --> $DIR/fn_must_use.rs:64:5
    |
 LL |     MyStruct::need_to_use_this_associated_function_value();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: unused return value of `std::cmp::PartialEq::eq` that must be used
   --> $DIR/fn_must_use.rs:70:5
    |
 LL |     2.eq(&3);
-   |     ^^^^^^^^^
+   |     ^^^^^^^^
 
 warning: unused return value of `std::cmp::PartialEq::eq` that must be used
   --> $DIR/fn_must_use.rs:71:5
    |
 LL |     m.eq(&n);
-   |     ^^^^^^^^^
+   |     ^^^^^^^^
 
 warning: unused comparison that must be used
   --> $DIR/fn_must_use.rs:74:5

src/test/ui/lint/unused/must-use-box-from-raw.stderr

@@ -2,7 +2,7 @@ warning: unused return value of `Box::<T>::from_raw` that must be used
   --> $DIR/must-use-box-from-raw.rs:8:5
    |
 LL |     Box::from_raw(ptr);
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^
    |
    = note: call `drop(from_raw(ptr))` if you intend to drop the `Box`
 note: the lint level is defined here

src/test/ui/lint/unused/must_use-array.stderr

@@ -2,7 +2,7 @@ error: unused array of `S` that must be used
   --> $DIR/must_use-array.rs:39:5
    |
 LL |     singleton();
-   |     ^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/must_use-array.rs:1:9
@@ -14,7 +14,7 @@ error: unused array of `S` that must be used
   --> $DIR/must_use-array.rs:40:5
    |
 LL |     many();
-   |     ^^^^^^^
+   |     ^^^^^^
 
 error: unused array of `S` in tuple element 0 that must be used
   --> $DIR/must_use-array.rs:41:6
@@ -26,7 +26,7 @@ error: unused array of implementers of `T` that must be used
   --> $DIR/must_use-array.rs:42:5
    |
 LL |     array_of_impl_trait();
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^
 
 error: unused array of boxed `T` trait objects in tuple element 1 that must be used
   --> $DIR/must_use-array.rs:43:5
@@ -38,7 +38,7 @@ error: unused array of arrays of arrays of `S` that must be used
   --> $DIR/must_use-array.rs:45:5
    |
 LL |     array_of_arrays_of_arrays();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 6 previous errors
 

src/test/ui/lint/unused/must_use-in-stdlib-traits.stderr

@@ -2,7 +2,7 @@ error: unused implementer of `Iterator` that must be used
   --> $DIR/must_use-in-stdlib-traits.rs:42:4
    |
 LL |    iterator();
-   |    ^^^^^^^^^^^
+   |    ^^^^^^^^^^
    |
    = note: iterators are lazy and do nothing unless consumed
 note: the lint level is defined here
@@ -15,31 +15,31 @@ error: unused implementer of `Future` that must be used
   --> $DIR/must_use-in-stdlib-traits.rs:43:4
    |
 LL |    future();
-   |    ^^^^^^^^^
+   |    ^^^^^^^^
    |
    = note: futures do nothing unless you `.await` or poll them
 
 error: unused implementer of `FnOnce` that must be used
   --> $DIR/must_use-in-stdlib-traits.rs:44:4
    |
 LL |    square_fn_once();
-   |    ^^^^^^^^^^^^^^^^^
+   |    ^^^^^^^^^^^^^^^^
    |
    = note: closures are lazy and do nothing unless called
 
 error: unused implementer of `FnMut` that must be used
   --> $DIR/must_use-in-stdlib-traits.rs:45:4
    |
 LL |    square_fn_mut();
-   |    ^^^^^^^^^^^^^^^^
+   |    ^^^^^^^^^^^^^^^
    |
    = note: closures are lazy and do nothing unless called
 
 error: unused implementer of `Fn` that must be used
   --> $DIR/must_use-in-stdlib-traits.rs:46:4
    |
 LL |    square_fn();
-   |    ^^^^^^^^^^^^
+   |    ^^^^^^^^^^^
    |
    = note: closures are lazy and do nothing unless called
 

src/test/ui/lint/unused/must_use-trait.stderr

@@ -2,7 +2,7 @@ error: unused implementer of `Critical` that must be used
   --> $DIR/must_use-trait.rs:33:5
    |
 LL |     get_critical();
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/must_use-trait.rs:1:9
@@ -14,13 +14,13 @@ error: unused boxed `Critical` trait object that must be used
   --> $DIR/must_use-trait.rs:34:5
    |
 LL |     get_boxed_critical();
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^
 
 error: unused boxed boxed `Critical` trait object that must be used
   --> $DIR/must_use-trait.rs:35:5
    |
 LL |     get_nested_boxed_critical();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: unused boxed `Critical` trait object in tuple element 1 that must be used
   --> $DIR/must_use-trait.rs:37:5

src/test/ui/lint/unused/must_use-unit.stderr

@@ -2,7 +2,7 @@ error: unused return value of `foo` that must be used
   --> $DIR/must_use-unit.rs:13:5
    |
 LL |     foo();
-   |     ^^^^^^
+   |     ^^^^^
    |
 note: the lint level is defined here
   --> $DIR/must_use-unit.rs:2:9
@@ -14,7 +14,7 @@ error: unused return value of `bar` that must be used
   --> $DIR/must_use-unit.rs:15:5
    |
 LL |     bar();
-   |     ^^^^^^
+   |     ^^^^^
 
 error: aborting due to 2 previous errors