Rollup merge of #78235 - Aaron1011:closure-ret-infer, r=varkor

Explain where the closure return type was inferred

Fixes #78193

src/test/ui/closures/closure-return-type-mismatch.rs

@@ -0,0 +1,17 @@
+fn main() {
+    || {
+        if false {
+            return "test";
+        }
+        let a = true;
+        a //~ ERROR mismatched types
+    };
+
+    || -> bool {
+        if false {
+            return "hello" //~ ERROR mismatched types
+        };
+        let b = true;
+        b
+    };
+}

src/test/ui/closures/closure-return-type-mismatch.stderr

@@ -0,0 +1,21 @@
+error[E0308]: mismatched types
+  --> $DIR/closure-return-type-mismatch.rs:7:9
+   |
+LL |         a
+   |         ^ expected `&str`, found `bool`
+   |
+note: return type inferred to be `&str` here
+  --> $DIR/closure-return-type-mismatch.rs:4:20
+   |
+LL |             return "test";
+   |                    ^^^^^^
+
+error[E0308]: mismatched types
+  --> $DIR/closure-return-type-mismatch.rs:12:20
+   |
+LL |             return "hello"
+   |                    ^^^^^^^ expected `bool`, found `&str`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/generator/type-mismatch-signature-deduction.stderr

@@ -6,6 +6,11 @@ LL |         5
    |
    = note: expected type `std::result::Result<{integer}, _>`
               found type `{integer}`
+note: return type inferred to be `std::result::Result<{integer}, _>` here
+  --> $DIR/type-mismatch-signature-deduction.rs:8:20
+   |
+LL |             return Ok(6);
+   |                    ^^^^^
 
 error[E0271]: type mismatch resolving `<[generator@$DIR/type-mismatch-signature-deduction.rs:6:5: 14:6] as Generator>::Return == i32`
   --> $DIR/type-mismatch-signature-deduction.rs:5:13