Tweak field parse error recovery

Author: estebank

src/libsyntax/parse/parser.rs

@@ -2695,28 +2695,12 @@ impl<'a> Parser<'a> {
                 break;
             }
 
-            let mut recovery_field = None;
-            if let token::Ident(ident, _) = self.token {
-                if !self.token.is_reserved_ident() {
-                    let mut ident = ident.clone();
-                    ident.span = self.span;
-                    recovery_field = Some(ast::Field {
-                        ident,
-                        span: self.span,
-                        expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()),
-                        is_shorthand: true,
-                        attrs: ThinVec::new(),
-                    });
-                }
-            }
+            let mut parsed_field = None;
             match self.parse_field() {
-                Ok(f) => fields.push(f),
+                Ok(f) => parsed_field = Some(f),
                 Err(mut e) => {
                     e.span_label(struct_sp, "while parsing this struct");
                     e.emit();
-                    if let Some(f) = recovery_field {
-                        fields.push(f);
-                    }
 
                     // If the next token is a comma, then try to parse
                     // what comes next as additional fields, rather than
@@ -2732,7 +2716,10 @@ impl<'a> Parser<'a> {
 
             match self.expect_one_of(&[token::Comma],
                                      &[token::CloseDelim(token::Brace)]) {
-                Ok(()) => {}
+                Ok(()) => if let Some(f) = parsed_field {
+                    // only include the field if there's no parse error
+                    fields.push(f);
+                }
                 Err(mut e) => {
                     e.span_label(struct_sp, "while parsing this struct");
                     e.emit();

src/test/ui/issues/issue-52496.rs

@@ -7,7 +7,6 @@ fn main() {
     let bar = 1.5f32;
     let _ = Foo { bar.into(), bat: -1, . };
     //~^ ERROR expected one of
-    //~| ERROR mismatched types
-    //~| ERROR missing field `baz` in initializer of `Foo`
+    //~| ERROR missing fields `bar`, `baz` in initializer of `Foo`
     //~| ERROR expected identifier, found `.`
 }

src/test/ui/issues/issue-52496.stderr

@@ -26,23 +26,12 @@ error[E0063]: missing field `bat` in initializer of `Foo`
 LL |     let _ = Foo { bar: .5, baz: 42 };
    |             ^^^ missing `bat`
 
-error[E0308]: mismatched types
-  --> $DIR/issue-52496.rs:8:19
-   |
-LL |     let _ = Foo { bar.into(), bat: -1, . };
-   |                   ^^^ expected f64, found f32
-help: you can cast an `f32` to `f64` in a lossless way
-   |
-LL |     let _ = Foo { bar.into().into(), bat: -1, . };
-   |                   ^^^^^^^^^^
-
-error[E0063]: missing field `baz` in initializer of `Foo`
+error[E0063]: missing fields `bar`, `baz` in initializer of `Foo`
   --> $DIR/issue-52496.rs:8:13
    |
 LL |     let _ = Foo { bar.into(), bat: -1, . };
-   |             ^^^ missing `baz`
+   |             ^^^ missing `bar`, `baz`
 
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 
-Some errors occurred: E0063, E0308.
-For more information about an error, try `rustc --explain E0063`.
+For more information about this error, try `rustc --explain E0063`.

src/test/ui/parser/removed-syntax-with-1.rs

@@ -7,5 +7,5 @@ fn main() {
     let a = S { foo: (), bar: () };
     let b = S { foo: () with a };
     //~^ ERROR expected one of `,`, `.`, `?`, `}`, or an operator, found `with`
-    //~| ERROR missing field `bar` in initializer of `main::S`
+    //~| ERROR missing fields `bar`, `foo` in initializer of `main::S`
 }

src/test/ui/parser/removed-syntax-with-1.stderr

@@ -6,11 +6,11 @@ LL |     let b = S { foo: () with a };
    |             |
    |             while parsing this struct
 
-error[E0063]: missing field `bar` in initializer of `main::S`
+error[E0063]: missing fields `bar`, `foo` in initializer of `main::S`
   --> $DIR/removed-syntax-with-1.rs:8:13
    |
 LL |     let b = S { foo: () with a };
-   |             ^ missing `bar`
+   |             ^ missing `bar`, `foo`
 
 error: aborting due to 2 previous errors
 

src/test/ui/parser/removed-syntax-with-2.rs

@@ -7,6 +7,5 @@ fn main() {
     let a = S { foo: (), bar: () };
     let b = S { foo: (), with a };
     //~^ ERROR expected one of `,` or `}`, found `a`
-    //~| ERROR cannot find value `with` in this scope
-    //~| ERROR struct `main::S` has no field named `with`
+    //~| ERROR missing field `bar` in initializer of `main::S`
 }

src/test/ui/parser/removed-syntax-with-2.stderr

@@ -6,21 +6,12 @@ LL |     let b = S { foo: (), with a };
    |             |
    |             while parsing this struct
 
-error[E0425]: cannot find value `with` in this scope
-  --> $DIR/removed-syntax-with-2.rs:8:26
+error[E0063]: missing field `bar` in initializer of `main::S`
+  --> $DIR/removed-syntax-with-2.rs:8:13
    |
 LL |     let b = S { foo: (), with a };
-   |                          ^^^^ not found in this scope
+   |             ^ missing `bar`
 
-error[E0560]: struct `main::S` has no field named `with`
-  --> $DIR/removed-syntax-with-2.rs:8:26
-   |
-LL |     let b = S { foo: (), with a };
-   |                          ^^^^ `main::S` does not have this field
-   |
-   = note: available fields are: `foo`, `bar`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors occurred: E0425, E0560.
-For more information about an error, try `rustc --explain E0425`.
+For more information about this error, try `rustc --explain E0063`.