Make sure we don't lose default struct value when formatting struct

Author: compiler-errors

src/tools/rustfmt/src/items.rs

@@ -1947,6 +1947,10 @@ pub(crate) fn rewrite_struct_field(
     if contains_skip(&field.attrs) {
         return Ok(context.snippet(field.span()).to_owned());
     }
+    // FIXME(default_field_values): Implement formatting.
+    if field.default.is_some() {
+        return Err(RewriteError::SkipFormatting);
+    }
 
     let type_annotation_spacing = type_annotation_spacing(context.config);
     let prefix = rewrite_struct_field_prefix(context, field)?;

src/tools/rustfmt/tests/source/default-field-values.rs

@@ -0,0 +1,11 @@
+// Test for now that nightly default field values are left alone for now.
+
+struct Foo {
+    default_field:    Spacing =    /* uwu */ 0,
+}
+
+a_macro!(
+    struct Foo2 {
+        default_field:    Spacing =    /* uwu */ 0,
+    }
+);

src/tools/rustfmt/tests/target/default-field-values.rs

@@ -0,0 +1,11 @@
+// Test for now that nightly default field values are left alone for now.
+
+struct Foo {
+    default_field:    Spacing =    /* uwu */ 0,
+}
+
+a_macro!(
+    struct Foo2 {
+        default_field:    Spacing =    /* uwu */ 0,
+    }
+);