Turn nonzeroing move hints back off by default.

This is a temporary workaround for the bugs that have been found in
the implementation of 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 this back on by default.

(If you want to play with the known-to-be-buggy optimization in the
meantime, you can opt-back in via the debugging option that this
commit is toggling.)

diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index f74bb9ee89ad080d6620c562a2fd73fc9c56f485..c5db7cd718b8ed931f6946d42fbb1cd05d253b82 100644 (file)
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -596,8 +596,8 @@ fn parse_passes(slot: &mut Passes, v: Option<&str>) -> bool {
           "Force drop flag checks on or off"),
     trace_macros: bool = (false, parse_bool,
           "For every macro invocation, print its name and arguments"),
-    disable_nonzeroing_move_hints: bool = (false, parse_bool,
-          "Force nonzeroing move optimization off"),
+    enable_nonzeroing_move_hints: bool = (false, parse_bool,
+          "Force nonzeroing move optimization on"),
 }
 
 pub fn default_lib_output() -> CrateType {

diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index efd46d35f56b7adb9573383cb4f1533821d6d73d..99a58f07ae62bf6e3c9ec5d0c1b84bcca1a8c056 100644 (file)
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -273,7 +273,7 @@ pub fn print_enum_sizes(&self) -> bool {
         self.opts.debugging_opts.print_enum_sizes
     }
     pub fn nonzeroing_move_hints(&self) -> bool {
-        !self.opts.debugging_opts.disable_nonzeroing_move_hints
+        self.opts.debugging_opts.enable_nonzeroing_move_hints
     }
     pub fn sysroot<'a>(&'a self) -> &'a Path {
         match self.opts.maybe_sysroot {