Auto merge of #86385 - JohnTitor:use-attrvec, r=davidtwco

Use `AttrVec` for `Arm`, `FieldDef`, and `Variant`

Uses `AttrVec` for `Arm`, `FieldDef`, and `Variant`, i.e., where the size of the vector can be empty often.
Skips `Crate` and `Item` because I think they may have the attributes on common cases and need more work outside of `rustc_ast` (e.g. rustc_expand needs a lot of tweaks). But if it's reasonable to change, I'm happy to do so.

Fixes #77662

2 files changed, 5 insertions, 5 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index c8789abc142..88ebf4aca23 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2116,7 +2116,7 @@ impl<'a> Parser<'a> {
                     let span = body.span;
                     return Ok((
                         ast::Arm {
-                            attrs,
+                            attrs: attrs.into(),
                             pat,
                             guard,
                             body,
@@ -2170,7 +2170,7 @@ impl<'a> Parser<'a> {
 
             Ok((
                 ast::Arm {
-                    attrs,
+                    attrs: attrs.into(),
                     pat,
                     guard,
                     body: expr,
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 54e6ff6272c..2daa9e2485b 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -1143,7 +1143,7 @@ impl<'a> Parser<'a> {
                     ident,
                     vis,
                     id: DUMMY_NODE_ID,
-                    attrs: variant_attrs,
+                    attrs: variant_attrs.into(),
                     data: struct_def,
                     disr_expr,
                     span: vlo.to(this.prev_token.span),
@@ -1286,7 +1286,7 @@ impl<'a> Parser<'a> {
                         ident: None,
                         id: DUMMY_NODE_ID,
                         ty,
-                        attrs,
+                        attrs: attrs.into(),
                         is_placeholder: false,
                     },
                     TrailingToken::MaybeComma,
@@ -1460,7 +1460,7 @@ impl<'a> Parser<'a> {
             vis,
             id: DUMMY_NODE_ID,
             ty,
-            attrs,
+            attrs: attrs.into(),
             is_placeholder: false,
         })
     }