From 4c0c4e554631b01280d29a0a951fb804e319e7d9 Mon Sep 17 00:00:00 2001 From: Alex Burka Date: Mon, 14 Dec 2015 12:53:26 -0500 Subject: [PATCH 1/2] add failing run-pass test for #30371 --- src/test/run-pass/issue-30371.rs | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 src/test/run-pass/issue-30371.rs diff --git a/src/test/run-pass/issue-30371.rs b/src/test/run-pass/issue-30371.rs new file mode 100644 index 00000000000..a4ab475e9ea --- /dev/null +++ b/src/test/run-pass/issue-30371.rs @@ -0,0 +1,18 @@ +// Copyright 2012 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![deny(unused_variables)] + +fn main() { + for _ in match return () { + () => Some(0), + } {} +} + From e0a526015da284588dba24bf9446636d50bfbf81 Mon Sep 17 00:00:00 2001 From: Alex Burka Date: Mon, 14 Dec 2015 13:36:45 -0500 Subject: [PATCH 2/2] evade unused_variables lint in for-loop desugaring --- src/librustc_front/lowering.rs | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/librustc_front/lowering.rs b/src/librustc_front/lowering.rs index c0b10fb8912..da561a0b322 100644 --- a/src/librustc_front/lowering.rs +++ b/src/librustc_front/lowering.rs @@ -1499,8 +1499,9 @@ pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P { hir::MatchSource::ForLoopDesugar, None); - // `{ let result = ...; result }` - let result_ident = lctx.str_to_ident("result"); + // `{ let _result = ...; _result }` + // underscore prevents an unused_variables lint if the head diverges + let result_ident = lctx.str_to_ident("_result"); let let_stmt = stmt_let(lctx, e.span, false, result_ident, match_expr, None); let result = expr_ident(lctx, e.span, result_ident, None); let block = block_all(lctx, e.span, vec![let_stmt], Some(result));