Auto merge of #66994 - Centril:stmt-polish, r=estebank

refactor expr & stmt parsing + improve recovery

Summary of important changes (best read commit-by-commit, ignoring whitespace changes):

- `AttrVec` is introduces as an alias for `ThinVec<Attribute>`
- `parse_expr_bottom` and `parse_stmt` are thoroughly refactored.
- Extract diagnostics logic for `vec![...]` in a pattern context.
- Recovery is added for `do catch { ... }`
- Recovery is added for `'label: non_block_expr`
- Recovery is added for `var $local`, `auto $local`, and `mut $local`. Fixes #65257.
- Recovery is added for `e1 and e2` and `e1 or e2`.
- ~~`macro_legacy_warnings` is turned into an error (has been a warning for 3 years!)~~
- Fixes #63396 by forward-porting #64105 which now works thanks to added recovery.
- `ui-fulldeps/ast_stmt_expr_attr.rs` is turned into UI and pretty tests.
- Recovery is fixed for `#[attr] if expr {}`

r? @estebank

1 files changed, 1 insertions, 2 deletions

diff --git a/src/libsyntax_expand/base.rs b/src/libsyntax_expand/base.rs
index 75066a006bf..2ad327e872e 100644
--- a/src/libsyntax_expand/base.rs
+++ b/src/libsyntax_expand/base.rs
@@ -9,7 +9,6 @@ use syntax::mut_visit::{self, MutVisitor};
 use syntax::ptr::P;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Ident, Symbol};
-use syntax::ThinVec;
 use syntax::token;
 use syntax::tokenstream::{self, TokenStream};
 use syntax::visit::Visitor;
@@ -552,7 +551,7 @@ impl DummyResult {
             id: ast::DUMMY_NODE_ID,
             kind: if is_error { ast::ExprKind::Err } else { ast::ExprKind::Tup(Vec::new()) },
             span: sp,
-            attrs: ThinVec::new(),
+            attrs: ast::AttrVec::new(),
         })
     }