Remove unused option flag

src/librustc/session/config.rs

@@ -1233,8 +1233,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "for every macro invocation, print its name and arguments"),
     debug_macros: bool = (false, parse_bool, [TRACKED],
           "emit line numbers debug info inside macros"),
-    enable_nonzeroing_move_hints: bool = (false, parse_bool, [TRACKED],
-          "force nonzeroing move optimization on"),
     keep_hygiene_data: bool = (false, parse_bool, [UNTRACKED],
           "don't clear the hygiene data after analysis"),
     keep_ast: bool = (false, parse_bool, [UNTRACKED],
@@ -3153,10 +3151,6 @@ mod tests {
         opts.debugging_opts.force_overflow_checks = Some(true);
         assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());
 
-        opts = reference.clone();
-        opts.debugging_opts.enable_nonzeroing_move_hints = true;
-        assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());
-
         opts = reference.clone();
         opts.debugging_opts.show_span = Some(String::from("abc"));
         assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());

src/librustc/session/mod.rs

@@ -624,9 +624,6 @@ impl Session {
     pub fn unstable_options(&self) -> bool {
         self.opts.debugging_opts.unstable_options
     }
-    pub fn nonzeroing_move_hints(&self) -> bool {
-        self.opts.debugging_opts.enable_nonzeroing_move_hints
-    }
     pub fn overflow_checks(&self) -> bool {
         self.opts
             .cg