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, 5 insertions, 6 deletions

diff --git a/src/librustc_parse/parser/pat.rs b/src/librustc_parse/parser/pat.rs
index 117b92dc9a5..593fb30bb75 100644
--- a/src/librustc_parse/parser/pat.rs
+++ b/src/librustc_parse/parser/pat.rs
@@ -1,12 +1,11 @@
 use super::{Parser, PathStyle};
 use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
 use rustc_errors::{PResult, Applicability, DiagnosticBuilder};
-use syntax::ast::{self, Attribute, Pat, PatKind, FieldPat, RangeEnd, RangeSyntax, Mac};
+use syntax::ast::{self, AttrVec, Attribute, Pat, PatKind, FieldPat, RangeEnd, RangeSyntax, Mac};
 use syntax::ast::{BindingMode, Ident, Mutability, Path, QSelf, Expr, ExprKind};
 use syntax::mut_visit::{noop_visit_pat, noop_visit_mac, MutVisitor};
 use syntax::ptr::P;
 use syntax::print::pprust;
-use syntax::ThinVec;
 use syntax::token;
 use syntax_pos::source_map::{respan, Span, Spanned};
 use syntax_pos::symbol::{kw, sym};
@@ -636,7 +635,7 @@ impl<'a> Parser<'a> {
         let op_span = self.token.span;
         // Parse range
         let span = lo.to(self.prev_span);
-        let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
+        let begin = self.mk_expr(span, ExprKind::Path(qself, path), AttrVec::new());
         self.bump();
         let end = self.parse_pat_range_end_opt(&begin, form)?;
         Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
@@ -693,7 +692,7 @@ impl<'a> Parser<'a> {
         let lo = self.prev_span;
         let end = self.parse_pat_range_end()?;
         let range_span = lo.to(end.span);
-        let begin = self.mk_expr(range_span, ExprKind::Err, ThinVec::new());
+        let begin = self.mk_expr(range_span, ExprKind::Err, AttrVec::new());
 
         self.diagnostic()
             .struct_span_err(range_span, &format!("`{}X` range patterns are not supported", form))
@@ -731,7 +730,7 @@ impl<'a> Parser<'a> {
                 )
                 .emit();
 
-            Ok(self.mk_expr(range_span, ExprKind::Err, ThinVec::new()))
+            Ok(self.mk_expr(range_span, ExprKind::Err, AttrVec::new()))
         }
     }
 
@@ -747,7 +746,7 @@ impl<'a> Parser<'a> {
                 (None, self.parse_path(PathStyle::Expr)?)
             };
             let hi = self.prev_span;
-            Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
+            Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), AttrVec::new()))
         } else {
             self.parse_literal_maybe_minus()
         }