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Auto merge of #27582 - pnkfelix:disable-nonzeroing-move-hint-by-default, r=nikomatsakis
Turn nonzeroing move hints back off by default. Works around bugs injected by PR #26173. * (@pnkfelix is unavailable in the short-term (i.e. for the next week) to fix them.) * When the bugs are fixed, we will turn nonzeroing move hints back on by default. Fix #27401
2 parents ab77c1d + 1a68b18 commit 1b5d521

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3 files changed

+39
-3
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3 files changed

+39
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src/librustc/session/config.rs

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@@ -596,8 +596,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
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"Force drop flag checks on or off"),
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trace_macros: bool = (false, parse_bool,
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"For every macro invocation, print its name and arguments"),
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disable_nonzeroing_move_hints: bool = (false, parse_bool,
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"Force nonzeroing move optimization off"),
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enable_nonzeroing_move_hints: bool = (false, parse_bool,
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"Force nonzeroing move optimization on"),
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}
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pub fn default_lib_output() -> CrateType {

src/librustc/session/mod.rs

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@@ -273,7 +273,7 @@ impl Session {
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self.opts.debugging_opts.print_enum_sizes
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}
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pub fn nonzeroing_move_hints(&self) -> bool {
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!self.opts.debugging_opts.disable_nonzeroing_move_hints
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self.opts.debugging_opts.enable_nonzeroing_move_hints
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}
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pub fn sysroot<'a>(&'a self) -> &'a Path {
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match self.opts.maybe_sysroot {
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@@ -0,0 +1,36 @@
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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// ignore-pretty #27582
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// Check that when a `let`-binding occurs in a loop, its associated
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// drop-flag is reinitialized (to indicate "needs-drop" at the end of
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// the owning variable's scope).
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struct A<'a>(&'a mut i32);
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impl<'a> Drop for A<'a> {
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fn drop(&mut self) {
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*self.0 += 1;
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}
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}
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fn main() {
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let mut cnt = 0;
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for i in 0..2 {
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let a = A(&mut cnt);
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if i == 1 { // Note that
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break; // both this break
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} // and also
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drop(a); // this move of `a`
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// are necessary to expose the bug
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}
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assert_eq!(cnt, 2);
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}

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