Take a slice in stmt_let_pat.

Author: cjgillot

compiler/rustc_ast_lowering/src/expr.rs

@@ -1026,7 +1026,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         // Introduce a `let` for destructuring: `let (lhs1, lhs2) = t`.
         let destructure_let = self.stmt_let_pat(
-            ThinVec::new(),
+            &[],
             whole_span,
             Some(rhs),
             pat,
@@ -1785,7 +1785,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         // `let mut __next`
         let next_let = self.stmt_let_pat(
-            ThinVec::new(),
+            &[],
             desugared_span,
             None,
             next_pat,
@@ -1795,7 +1795,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // `let <pat> = __next`
         let pat = self.lower_pat(pat);
         let pat_let = self.stmt_let_pat(
-            ThinVec::new(),
+            &[],
             desugared_span,
             Some(next_expr),
             pat,

compiler/rustc_ast_lowering/src/item.rs

@@ -1177,8 +1177,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 //
                 // If this is the simple case, this parameter will end up being the same as the
                 // original parameter, but with a different pattern id.
-                let mut stmt_attrs = AttrVec::new();
-                stmt_attrs.extend(parameter.attrs.iter().cloned());
+                let stmt_attrs = this.attrs[parameter.hir_id];
                 let (new_parameter_pat, new_parameter_id) = this.pat_ident(desugared_span, ident);
                 let new_parameter = hir::Param {
                     attrs: parameter.attrs,
@@ -1224,7 +1223,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     );
                     let move_expr = this.expr_ident(desugared_span, ident, new_parameter_id);
                     let move_stmt = this.stmt_let_pat(
-                        AttrVec::new(),
+                        &[],
                         desugared_span,
                         Some(move_expr),
                         move_pat,

compiler/rustc_ast_lowering/src/lib.rs

@@ -2526,15 +2526,23 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
     fn stmt_let_pat(
         &mut self,
-        attrs: AttrVec,
+        attrs: &'hir [Attribute],
         span: Span,
         init: Option<&'hir hir::Expr<'hir>>,
         pat: &'hir hir::Pat<'hir>,
         source: hir::LocalSource,
     ) -> hir::Stmt<'hir> {
         let hir_id = self.next_id();
-        self.attrs.push_sparse(hir_id, &*self.arena.alloc_from_iter(attrs.iter().cloned()));
-        let local = hir::Local { attrs, hir_id, init, pat, source, span, ty: None };
+        self.attrs.push_sparse(hir_id, attrs);
+        let local = hir::Local {
+            attrs: attrs.iter().cloned().collect::<Vec<_>>().into(),
+            hir_id,
+            init,
+            pat,
+            source,
+            span,
+            ty: None,
+        };
         self.stmt(span, hir::StmtKind::Local(self.arena.alloc(local)))
     }