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-rw-r--r--compiler/rustc_ast_lowering/src/expr.rs87
1 files changed, 54 insertions, 33 deletions
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 7b8070d3c..ec9c39350 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -60,7 +60,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
hir::ExprKind::Call(f, self.lower_exprs(args))
}
}
- ExprKind::MethodCall(ref seg, ref args, span) => {
+ ExprKind::MethodCall(ref seg, ref receiver, ref args, span) => {
let hir_seg = self.arena.alloc(self.lower_path_segment(
e.span,
seg,
@@ -68,9 +68,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
ParenthesizedGenericArgs::Err,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
));
- let receiver = self.lower_expr(&args[0]);
+ let receiver = self.lower_expr(receiver);
let args =
- self.arena.alloc_from_iter(args[1..].iter().map(|x| self.lower_expr_mut(x)));
+ self.arena.alloc_from_iter(args.iter().map(|x| self.lower_expr_mut(x)));
hir::ExprKind::MethodCall(hir_seg, receiver, args, self.lower_span(span))
}
ExprKind::Binary(binop, ref lhs, ref rhs) => {
@@ -359,7 +359,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let node_id = self.next_node_id();
// Add a definition for the in-band const def.
- self.create_def(parent_def_id, node_id, DefPathData::AnonConst);
+ self.create_def(parent_def_id.def_id, node_id, DefPathData::AnonConst);
let anon_const = AnonConst { id: node_id, value: arg };
generic_args.push(AngleBracketedArg::Arg(GenericArg::Const(anon_const)));
@@ -387,32 +387,58 @@ impl<'hir> LoweringContext<'_, 'hir> {
then: &Block,
else_opt: Option<&Expr>,
) -> hir::ExprKind<'hir> {
- let lowered_cond = self.lower_expr(cond);
- let new_cond = self.manage_let_cond(lowered_cond);
+ let lowered_cond = self.lower_cond(cond);
let then_expr = self.lower_block_expr(then);
if let Some(rslt) = else_opt {
- hir::ExprKind::If(new_cond, self.arena.alloc(then_expr), Some(self.lower_expr(rslt)))
+ hir::ExprKind::If(
+ lowered_cond,
+ self.arena.alloc(then_expr),
+ Some(self.lower_expr(rslt)),
+ )
} else {
- hir::ExprKind::If(new_cond, self.arena.alloc(then_expr), None)
+ hir::ExprKind::If(lowered_cond, self.arena.alloc(then_expr), None)
}
}
- // If `cond` kind is `let`, returns `let`. Otherwise, wraps and returns `cond`
- // in a temporary block.
- fn manage_let_cond(&mut self, cond: &'hir hir::Expr<'hir>) -> &'hir hir::Expr<'hir> {
- fn has_let_expr<'hir>(expr: &'hir hir::Expr<'hir>) -> bool {
- match expr.kind {
- hir::ExprKind::Binary(_, lhs, rhs) => has_let_expr(lhs) || has_let_expr(rhs),
- hir::ExprKind::Let(..) => true,
+ // Lowers a condition (i.e. `cond` in `if cond` or `while cond`), wrapping it in a terminating scope
+ // so that temporaries created in the condition don't live beyond it.
+ fn lower_cond(&mut self, cond: &Expr) -> &'hir hir::Expr<'hir> {
+ fn has_let_expr(expr: &Expr) -> bool {
+ match &expr.kind {
+ ExprKind::Binary(_, lhs, rhs) => has_let_expr(lhs) || has_let_expr(rhs),
+ ExprKind::Let(..) => true,
_ => false,
}
}
- if has_let_expr(cond) {
- cond
- } else {
- let reason = DesugaringKind::CondTemporary;
- let span_block = self.mark_span_with_reason(reason, cond.span, None);
- self.expr_drop_temps(span_block, cond, AttrVec::new())
+
+ // We have to take special care for `let` exprs in the condition, e.g. in
+ // `if let pat = val` or `if foo && let pat = val`, as we _do_ want `val` to live beyond the
+ // condition in this case.
+ //
+ // In order to mantain the drop behavior for the non `let` parts of the condition,
+ // we still wrap them in terminating scopes, e.g. `if foo && let pat = val` essentially
+ // gets transformed into `if { let _t = foo; _t } && let pat = val`
+ match &cond.kind {
+ ExprKind::Binary(op @ Spanned { node: ast::BinOpKind::And, .. }, lhs, rhs)
+ if has_let_expr(cond) =>
+ {
+ let op = self.lower_binop(*op);
+ let lhs = self.lower_cond(lhs);
+ let rhs = self.lower_cond(rhs);
+
+ self.arena.alloc(self.expr(
+ cond.span,
+ hir::ExprKind::Binary(op, lhs, rhs),
+ AttrVec::new(),
+ ))
+ }
+ ExprKind::Let(..) => self.lower_expr(cond),
+ _ => {
+ let cond = self.lower_expr(cond);
+ let reason = DesugaringKind::CondTemporary;
+ let span_block = self.mark_span_with_reason(reason, cond.span, None);
+ self.expr_drop_temps(span_block, cond, AttrVec::new())
+ }
}
}
@@ -439,14 +465,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
body: &Block,
opt_label: Option<Label>,
) -> hir::ExprKind<'hir> {
- let lowered_cond = self.with_loop_condition_scope(|t| t.lower_expr(cond));
- let new_cond = self.manage_let_cond(lowered_cond);
+ let lowered_cond = self.with_loop_condition_scope(|t| t.lower_cond(cond));
let then = self.lower_block_expr(body);
let expr_break = self.expr_break(span, AttrVec::new());
let stmt_break = self.stmt_expr(span, expr_break);
let else_blk = self.block_all(span, arena_vec![self; stmt_break], None);
let else_expr = self.arena.alloc(self.expr_block(else_blk, AttrVec::new()));
- let if_kind = hir::ExprKind::If(new_cond, self.arena.alloc(then), Some(else_expr));
+ let if_kind = hir::ExprKind::If(lowered_cond, self.arena.alloc(then), Some(else_expr));
let if_expr = self.expr(span, if_kind, AttrVec::new());
let block = self.block_expr(self.arena.alloc(if_expr));
let span = self.lower_span(span.with_hi(cond.span.hi()));
@@ -1044,9 +1069,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
if let ExprKind::Path(qself, path) = &expr.kind {
// Does the path resolve to something disallowed in a tuple struct/variant pattern?
if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
- if partial_res.unresolved_segments() == 0
- && !partial_res.base_res().expected_in_tuple_struct_pat()
- {
+ if let Some(res) = partial_res.full_res() && !res.expected_in_tuple_struct_pat() {
return None;
}
}
@@ -1066,9 +1089,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
if let ExprKind::Path(qself, path) = &expr.kind {
// Does the path resolve to something disallowed in a unit struct/variant pattern?
if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
- if partial_res.unresolved_segments() == 0
- && !partial_res.base_res().expected_in_unit_struct_pat()
- {
+ if let Some(res) = partial_res.full_res() && !res.expected_in_unit_struct_pat() {
return None;
}
}
@@ -1609,11 +1630,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
/// Desugar `ExprKind::Yeet` from: `do yeet <expr>` into:
- /// ```rust
+ /// ```ignore(illustrative)
/// // If there is an enclosing `try {...}`:
- /// break 'catch_target FromResidual::from_residual(Yeet(residual)),
+ /// break 'catch_target FromResidual::from_residual(Yeet(residual));
/// // Otherwise:
- /// return FromResidual::from_residual(Yeet(residual)),
+ /// return FromResidual::from_residual(Yeet(residual));
/// ```
/// But to simplify this, there's a `from_yeet` lang item function which
/// handles the combined `FromResidual::from_residual(Yeet(residual))`.
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-10 21:06:04 +0000