Rollup merge of #82720 - henryboisdequin:fix-79040, r=oli-obk

Fix diagnostic suggests adding type `[type error]`

Fixes #79040

### Unresolved questions:

<del>Why does this change output the diagnostic twice (`src/test/ui/79040.rs`)?</del> Thanks `````@oli-obk`````

compiler/rustc_typeck/src/collect/type_of.rs

@@ -722,11 +722,12 @@ fn infer_placeholder_type(
                 format!("{}: {}", item_ident, ty),
                 Applicability::MachineApplicable,
             )
-            .emit();
+            .emit_unless(ty.references_error());
         }
         None => {
             let mut diag = bad_placeholder_type(tcx, vec![span]);
-            if !matches!(ty.kind(), ty::Error(_)) {
+
+            if !ty.references_error() {
                 diag.span_suggestion(
                     span,
                     "replace `_` with the correct type",
@@ -734,6 +735,7 @@ fn infer_placeholder_type(
                     Applicability::MaybeIncorrect,
                 );
             }
+
             diag.emit();
         }
     }

src/test/ui/parser/item-free-const-no-body-semantic-fail.rs

@@ -4,4 +4,3 @@ fn main() {}
 
 const A: u8; //~ ERROR free constant item without body
 const B; //~ ERROR free constant item without body
-//~^ ERROR missing type for `const` item

src/test/ui/parser/item-free-const-no-body-semantic-fail.stderr

@@ -14,11 +14,5 @@ LL | const B;
    |        |
    |        help: provide a definition for the constant: `= <expr>;`
 
-error: missing type for `const` item
-  --> $DIR/item-free-const-no-body-semantic-fail.rs:6:7
-   |
-LL | const B;
-   |       ^ help: provide a type for the item: `B: [type error]`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 

src/test/ui/parser/item-free-static-no-body-semantic-fail.rs

@@ -4,8 +4,6 @@ fn main() {}
 
 static A: u8; //~ ERROR free static item without body
 static B; //~ ERROR free static item without body
-//~^ ERROR missing type for `static` item
 
 static mut C: u8; //~ ERROR free static item without body
 static mut D; //~ ERROR free static item without body
-//~^ ERROR missing type for `static mut` item

src/test/ui/parser/item-free-static-no-body-semantic-fail.stderr

@@ -15,7 +15,7 @@ LL | static B;
    |         help: provide a definition for the static: `= <expr>;`
 
 error: free static item without body
-  --> $DIR/item-free-static-no-body-semantic-fail.rs:9:1
+  --> $DIR/item-free-static-no-body-semantic-fail.rs:8:1
    |
 LL | static mut C: u8;
    | ^^^^^^^^^^^^^^^^-
@@ -23,24 +23,12 @@ LL | static mut C: u8;
    |                 help: provide a definition for the static: `= <expr>;`
 
 error: free static item without body
-  --> $DIR/item-free-static-no-body-semantic-fail.rs:10:1
+  --> $DIR/item-free-static-no-body-semantic-fail.rs:9:1
    |
 LL | static mut D;
    | ^^^^^^^^^^^^-
    |             |
    |             help: provide a definition for the static: `= <expr>;`
 
-error: missing type for `static` item
-  --> $DIR/item-free-static-no-body-semantic-fail.rs:6:8
-   |
-LL | static B;
-   |        ^ help: provide a type for the item: `B: [type error]`
-
-error: missing type for `static mut` item
-  --> $DIR/item-free-static-no-body-semantic-fail.rs:10:12
-   |
-LL | static mut D;
-   |            ^ help: provide a type for the item: `D: [type error]`
-
-error: aborting due to 6 previous errors
+error: aborting due to 4 previous errors
 

src/test/ui/typeck/issue-79040.rs

+fn main() {
+    const FOO = "hello" + 1; //~ ERROR cannot add `{integer}` to `&str`
+    //~^ ERROR cannot add `{integer}` to `&str`
+    println!("{}", FOO);
+}

src/test/ui/typeck/issue-79040.stderr

+error[E0369]: cannot add `{integer}` to `&str`
+  --> $DIR/issue-79040.rs:2:25
+   |
+LL |     const FOO = "hello" + 1;
+   |                 ------- ^ - {integer}
+   |                 |
+   |                 &str
+
+error[E0369]: cannot add `{integer}` to `&str`
+  --> $DIR/issue-79040.rs:2:25
+   |
+LL |     const FOO = "hello" + 1;
+   |                 ------- ^ - {integer}
+   |                 |
+   |                 &str
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0369`.