Rollup merge of #88729 - estebank:struct-literal-using-parens, r=oli-obk

Recover from `Foo(a: 1, b: 2)`

Detect likely `struct` literal using parentheses as delimiters and emit
targeted suggestion instead of type ascription parse error.

Fix #61326.

src/test/ui/issues/issue-34255-1.rs

@@ -6,5 +6,5 @@ enum Test {
 
 fn main() {
     Test::Drill(field: 42);
-    //~^ ERROR expected type, found
+    //~^ ERROR invalid `struct` delimiters or `fn` call arguments
 }

src/test/ui/issues/issue-34255-1.stderr

@@ -1,13 +1,18 @@
-error: expected type, found `42`
-  --> $DIR/issue-34255-1.rs:8:24
+error: invalid `struct` delimiters or `fn` call arguments
+  --> $DIR/issue-34255-1.rs:8:5
    |
 LL |     Test::Drill(field: 42);
-   |                      - ^^ expected type
-   |                      |
-   |                      tried to parse a type due to this type ascription
+   |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+help: if `Test::Drill` is a struct, use braces as delimiters
+   |
+LL |     Test::Drill { field: 42 };
+   |                 ~           ~
+help: if `Test::Drill` is a function, use the arguments directly
+   |
+LL -     Test::Drill(field: 42);
+LL +     Test::Drill(42);
+   | 
 
 error: aborting due to previous error
 

src/test/ui/parser/issue-44406.rs

@@ -1,10 +1,10 @@
 macro_rules! foo {
     ($rest: tt) => {
-        bar(baz: $rest)
+        bar(baz: $rest) //~ ERROR invalid `struct` delimiters or `fn` call arguments
     }
 }
 
 fn main() {
-    foo!(true); //~ ERROR expected type, found keyword
+    foo!(true);
     //~^ ERROR expected identifier, found keyword
 }

src/test/ui/parser/issue-44406.stderr

@@ -9,17 +9,25 @@ help: you can escape reserved keywords to use them as identifiers
 LL |     foo!(r#true);
    |          ~~~~~~
 
-error: expected type, found keyword `true`
-  --> $DIR/issue-44406.rs:8:10
+error: invalid `struct` delimiters or `fn` call arguments
+  --> $DIR/issue-44406.rs:3:9
    |
 LL |         bar(baz: $rest)
-   |                - help: try using a semicolon: `;`
+   |         ^^^^^^^^^^^^^^^
 ...
 LL |     foo!(true);
-   |          ^^^^ expected type
+   |     ----------- in this macro invocation
    |
-   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+   = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: if `bar` is a struct, use braces as delimiters
+   |
+LL |         bar {  }
+   |             ~
+help: if `bar` is a function, use the arguments directly
+   |
+LL -         bar(baz: $rest)
+LL +         bar(true);
+   | 
 
 error: aborting due to 2 previous errors
 

src/test/ui/parser/recover-from-bad-variant.rs

@@ -5,7 +5,7 @@ enum Enum {
 
 fn main() {
     let x = Enum::Foo(a: 3, b: 4);
-    //~^ ERROR expected type, found `3`
+    //~^ ERROR invalid `struct` delimiters or `fn` call arguments
     match x {
         Enum::Foo(a, b) => {}
         //~^ ERROR expected tuple struct or tuple variant, found struct variant `Enum::Foo`

src/test/ui/parser/recover-from-bad-variant.stderr

@@ -1,13 +1,18 @@
-error: expected type, found `3`
-  --> $DIR/recover-from-bad-variant.rs:7:26
+error: invalid `struct` delimiters or `fn` call arguments
+  --> $DIR/recover-from-bad-variant.rs:7:13
    |
 LL |     let x = Enum::Foo(a: 3, b: 4);
-   |                        - ^ expected type
-   |                        |
-   |                        tried to parse a type due to this type ascription
+   |             ^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+help: if `Enum::Foo` is a struct, use braces as delimiters
+   |
+LL |     let x = Enum::Foo { a: 3, b: 4 };
+   |                       ~            ~
+help: if `Enum::Foo` is a function, use the arguments directly
+   |
+LL -     let x = Enum::Foo(a: 3, b: 4);
+LL +     let x = Enum::Foo(3, 4);
+   | 
 
 error[E0532]: expected tuple struct or tuple variant, found struct variant `Enum::Foo`
   --> $DIR/recover-from-bad-variant.rs:10:9