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, 3 insertions, 4 deletions

diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index 4d686fc310f..a8800082c9a 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -10,7 +10,6 @@ use rustc_data_structures::jobserver;
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use rustc_errors::registry::Registry;
 use rustc_metadata::dynamic_lib::DynamicLibrary;
@@ -24,7 +23,7 @@ use std::ops::DerefMut;
 use smallvec::SmallVec;
 use syntax::ptr::P;
 use syntax::mut_visit::{*, MutVisitor, visit_clobber};
-use syntax::ast::BlockCheckMode;
+use syntax::ast::{AttrVec, BlockCheckMode};
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax::source_map::{FileLoader, RealFileLoader, SourceMap};
 use syntax::symbol::{Symbol, sym};
@@ -741,7 +740,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
                 id: resolver.next_node_id(),
                 kind: ast::ExprKind::Block(P(b), None),
                 span: syntax_pos::DUMMY_SP,
-                attrs: ThinVec::new(),
+                attrs: AttrVec::new(),
             });
 
             ast::Stmt {
@@ -756,7 +755,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
             kind: ast::ExprKind::Loop(P(empty_block), None),
             id: self.resolver.next_node_id(),
             span: syntax_pos::DUMMY_SP,
-                attrs: ThinVec::new(),
+                attrs: AttrVec::new(),
         });
 
         let loop_stmt = ast::Stmt {