From f1aa8b2c01a97b0114f84b2d557e4598e6070515 Mon Sep 17 00:00:00 2001
From: Agustin Fernandez <juan.fernandez@opower.com>
Date: Mon, 28 Oct 2019 09:15:46 -0400
Subject: [PATCH] Output previous stable error messaging when using stable
build.
---
src/librustc/hir/lowering/expr.rs | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/src/librustc/hir/lowering/expr.rs b/src/librustc/hir/lowering/expr.rs
index d5fcc0ef6ede8..73db762a64bda 100644
--- a/src/librustc/hir/lowering/expr.rs
+++ b/src/librustc/hir/lowering/expr.rs
@@ -235,11 +235,20 @@ impl LoweringContext<'_> {
/// ```
fn lower_expr_let(&mut self, span: Span, pat: &Pat, scrutinee: &Expr) -> hir::ExprKind {
// If we got here, the `let` expression is not allowed.
- self.sess
- .struct_span_err(span, "`let` expressions are not supported here")
- .note("only supported directly in conditions of `if`- and `while`-expressions")
- .note("as well as when nested within `&&` and parenthesis in those conditions")
- .emit();
+
+ if self.sess.opts.unstable_features.is_nightly_build() {
+ self.sess
+ .struct_span_err(span, "`let` expressions are not supported here")
+ .note("only supported directly in conditions of `if`- and `while`-expressions")
+ .note("as well as when nested within `&&` and parenthesis in those conditions")
+ .emit();
+ }
+ else {
+ self.sess
+ .struct_span_err(span, "expected expression, found statement (`let`)")
+ .note("variable declaration using `let` is a statement")
+ .emit();
+ }
// For better recovery, we emit:
// ```