Bug 1531655 - Emit a configure error if rustc version >= 1.33 and --enable-rust-simd used. r=glandium

Differential Revision: https://phabricator.services.mozilla.com/D21649

--HG--
extra : moz-landing-system : lando

toolkit/moz.configure

@@ -705,11 +705,14 @@ set_config('MOZ_ENABLE_WEBRENDER', webrender.enable)
 option('--enable-rust-simd', env='MOZ_RUST_SIMD',
        help='Enable explicit SIMD in Rust code.')
 
-@depends('--enable-rust-simd', target)
-def rust_simd(value, target):
+@depends('--enable-rust-simd', target, rustc_info)
+def rust_simd(value, target, rustc_info):
     # As of 2018-06-05, the simd crate only works on aarch64,
     # armv7, x86 and x86_64.
     if target.cpu in ('aarch64', 'arm', 'x86', 'x86_64') and value:
+        if rustc_info and rustc_info.version >= Version('1.33.0'):
+            die('--enable-rust-simd does not work with Rust 1.33 or later. '
+                'See https://bugzilla.mozilla.org/show_bug.cgi?id=1521249 .')
         return True
 
 set_config('MOZ_RUST_SIMD', rust_simd)