diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/expr.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/expr.rs | 137 |
1 files changed, 38 insertions, 99 deletions
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs index 405e9035c4c..a0a63620c08 100644 --- a/compiler/rustc_ast_lowering/src/expr.rs +++ b/compiler/rustc_ast_lowering/src/expr.rs @@ -13,7 +13,7 @@ use rustc_session::parse::feature_err; use rustc_span::hygiene::ExpnId; use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned}; use rustc_span::symbol::{sym, Ident, Symbol}; -use rustc_span::{hygiene::ForLoopLoc, DUMMY_SP}; +use rustc_span::DUMMY_SP; impl<'hir> LoweringContext<'_, 'hir> { fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] { @@ -1308,16 +1308,13 @@ impl<'hir> LoweringContext<'_, 'hir> { /// Desugar `ExprForLoop` from: `[opt_ident]: for <pat> in <head> <body>` into: /// ```rust /// { - /// let result = match ::std::iter::IntoIterator::into_iter(<head>) { + /// let result = match IntoIterator::into_iter(<head>) { /// mut iter => { /// [opt_ident]: loop { - /// let mut __next; - /// match ::std::iter::Iterator::next(&mut iter) { - /// ::std::option::Option::Some(val) => __next = val, - /// ::std::option::Option::None => break + /// match Iterator::next(&mut iter) { + /// None => break, + /// Some(<pat>) => <body>, /// }; - /// let <pat> = __next; - /// StmtKind::Expr(<body>); /// } /// } /// }; @@ -1332,133 +1329,75 @@ impl<'hir> LoweringContext<'_, 'hir> { body: &Block, opt_label: Option<Label>, ) -> hir::Expr<'hir> { - // expand <head> let head = self.lower_expr_mut(head); - let desugared_span = - self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), head.span, None); - let e_span = self.lower_span(e.span); - - let iter = Ident::with_dummy_span(sym::iter); - - let next_ident = Ident::with_dummy_span(sym::__next); - let (next_pat, next_pat_hid) = self.pat_ident_binding_mode( - desugared_span, - next_ident, - hir::BindingAnnotation::Mutable, - ); - - // `::std::option::Option::Some(val) => __next = val` - let pat_arm = { - let val_ident = Ident::with_dummy_span(sym::val); - let pat_span = self.lower_span(pat.span); - let (val_pat, val_pat_hid) = self.pat_ident(pat_span, val_ident); - let val_expr = self.expr_ident(pat_span, val_ident, val_pat_hid); - let next_expr = self.expr_ident(pat_span, next_ident, next_pat_hid); - let assign = self.arena.alloc(self.expr( - pat_span, - hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat_span)), - ThinVec::new(), - )); - let some_pat = self.pat_some(pat_span, val_pat); - self.arm(some_pat, assign) - }; + let pat = self.lower_pat(pat); + let for_span = + self.mark_span_with_reason(DesugaringKind::ForLoop, self.lower_span(e.span), None); + let head_span = self.mark_span_with_reason(DesugaringKind::ForLoop, head.span, None); + let pat_span = self.mark_span_with_reason(DesugaringKind::ForLoop, pat.span, None); - // `::std::option::Option::None => break` - let break_arm = { + // `None => break` + let none_arm = { let break_expr = - self.with_loop_scope(e.id, |this| this.expr_break_alloc(e_span, ThinVec::new())); - let pat = self.pat_none(e_span); + self.with_loop_scope(e.id, |this| this.expr_break_alloc(for_span, ThinVec::new())); + let pat = self.pat_none(for_span); self.arm(pat, break_expr) }; + // Some(<pat>) => <body>, + let some_arm = { + let some_pat = self.pat_some(pat_span, pat); + let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false)); + let body_expr = self.arena.alloc(self.expr_block(body_block, ThinVec::new())); + self.arm(some_pat, body_expr) + }; + // `mut iter` + let iter = Ident::with_dummy_span(sym::iter); let (iter_pat, iter_pat_nid) = - self.pat_ident_binding_mode(desugared_span, iter, hir::BindingAnnotation::Mutable); + self.pat_ident_binding_mode(head_span, iter, hir::BindingAnnotation::Mutable); - // `match ::std::iter::Iterator::next(&mut iter) { ... }` + // `match Iterator::next(&mut iter) { ... }` let match_expr = { - let iter = self.expr_ident(desugared_span, iter, iter_pat_nid); - let ref_mut_iter = self.expr_mut_addr_of(desugared_span, iter); + let iter = self.expr_ident(head_span, iter, iter_pat_nid); + let ref_mut_iter = self.expr_mut_addr_of(head_span, iter); let next_expr = self.expr_call_lang_item_fn( - desugared_span, + head_span, hir::LangItem::IteratorNext, arena_vec![self; ref_mut_iter], ); - let arms = arena_vec![self; pat_arm, break_arm]; + let arms = arena_vec![self; none_arm, some_arm]; - self.expr_match(desugared_span, next_expr, arms, hir::MatchSource::ForLoopDesugar) + self.expr_match(head_span, next_expr, arms, hir::MatchSource::ForLoopDesugar) }; - let match_stmt = self.stmt_expr(desugared_span, match_expr); - - let next_expr = self.expr_ident(desugared_span, next_ident, next_pat_hid); - - // `let mut __next` - let next_let = self.stmt_let_pat( - None, - desugared_span, - None, - next_pat, - hir::LocalSource::ForLoopDesugar, - ); + let match_stmt = self.stmt_expr(for_span, match_expr); - // `let <pat> = __next` - let pat = self.lower_pat(pat); - let pat_let = self.stmt_let_pat( - None, - desugared_span, - Some(next_expr), - pat, - hir::LocalSource::ForLoopDesugar, - ); - - let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false)); - let body_expr = self.expr_block(body_block, ThinVec::new()); - let body_stmt = self.stmt_expr(body_block.span, body_expr); - - let loop_block = self.block_all( - e_span, - arena_vec![self; next_let, match_stmt, pat_let, body_stmt], - None, - ); + let loop_block = self.block_all(for_span, arena_vec![self; match_stmt], None); // `[opt_ident]: loop { ... }` let kind = hir::ExprKind::Loop( loop_block, self.lower_label(opt_label), hir::LoopSource::ForLoop, - self.lower_span(e_span.with_hi(head.span.hi())), + self.lower_span(for_span.with_hi(head.span.hi())), ); - let loop_expr = self.arena.alloc(hir::Expr { - hir_id: self.lower_node_id(e.id), - kind, - span: self.lower_span(e.span), - }); + let loop_expr = + self.arena.alloc(hir::Expr { hir_id: self.lower_node_id(e.id), kind, span: for_span }); // `mut iter => { ... }` let iter_arm = self.arm(iter_pat, loop_expr); - let into_iter_span = self.mark_span_with_reason( - DesugaringKind::ForLoop(ForLoopLoc::IntoIter), - head.span, - None, - ); - // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }` let into_iter_expr = { self.expr_call_lang_item_fn( - into_iter_span, + head_span, hir::LangItem::IntoIterIntoIter, arena_vec![self; head], ) }; - // #82462: to correctly diagnose borrow errors, the block that contains - // the iter expr needs to have a span that covers the loop body. - let desugared_full_span = - self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e_span, None); - let match_expr = self.arena.alloc(self.expr_match( - desugared_full_span, + for_span, into_iter_expr, arena_vec![self; iter_arm], hir::MatchSource::ForLoopDesugar, @@ -1472,7 +1411,7 @@ impl<'hir> LoweringContext<'_, 'hir> { // surrounding scope of the `match` since the `match` is not a terminating scope. // // Also, add the attributes to the outer returned expr node. - self.expr_drop_temps_mut(desugared_full_span, match_expr, attrs.into()) + self.expr_drop_temps_mut(for_span, match_expr, attrs.into()) } /// Desugar `ExprKind::Try` from: `<expr>?` into: |