Recover from invalid `struct` item syntax

Parse unsupported "default field const values":

```rust
struct S {
    field: Type = const_val,
}
```

Recover from small `:` typo and provide suggestion:

```rust
struct S {
    field; Type,
    field2= Type,
}
```

1 files changed, 35 insertions, 0 deletions

diff --git a/src/test/ui/parser/struct-default-values-and-missing-field-separator.fixed b/src/test/ui/parser/struct-default-values-and-missing-field-separator.fixed
new file mode 100644
index 00000000000..28191b82621
--- /dev/null
+++ b/src/test/ui/parser/struct-default-values-and-missing-field-separator.fixed
@@ -0,0 +1,35 @@
+// run-rustfix
+#![allow(dead_code)]
+
+enum E {
+    A,
+}
+
+struct S {
+    field1: i32, //~ ERROR default values on `struct` fields aren't supported
+    field2: E, //~ ERROR default values on `struct` fields aren't supported
+    field3: i32, //~ ERROR default values on `struct` fields aren't supported
+    field4: i32, //~ ERROR default values on `struct` fields aren't supported
+    field5: E, //~ ERROR default values on `struct` fields aren't supported
+    field6: E, //~ ERROR default values on `struct` fields aren't supported
+}
+
+struct S1 {
+    field1: i32, //~ ERROR expected `,`, or `}`, found `field2`
+    field2: E, //~ ERROR expected `,`, or `}`, found `field3`
+    field3: i32, //~ ERROR default values on `struct` fields aren't supported
+    field4: i32, //~ ERROR default values on `struct` fields aren't supported
+    field5: E, //~ ERROR default values on `struct` fields aren't supported
+    field6: E, //~ ERROR default values on `struct` fields aren't supported
+}
+
+struct S2 {
+    field1 : i32, //~ ERROR expected `:`, found `=`
+    field2: E, //~ ERROR expected `:`, found `;`
+}
+
+const fn foo(_: i32) -> E {
+    E::A
+}
+
+fn main() {}