Fix syntax checking on --bench files. (#153)

Author: ehuss

SyntaxCheckPlugin.py

@@ -129,11 +129,11 @@ def get_rustc_messages(self, settings, file_name):
         for (target_src, target_args) in targets:
             args = ['rustc', target_args, '--',
                     '-Zno-trans', '-Zunstable-options', '--error-format=json']
-            if (settings.get('rust_syntax_checking_include_tests', True) and
-                '--test' not in target_args
-               ):
-                args.append('--test')
-            yield (target_src, self.run_cargo(args, cwd=cwd))
+
+            if settings.get('rust_syntax_checking_include_tests', True):
+                if not ('--test' in target_args or '--bench' in target_args):
+                    args.append('--test')
+            yield (target_src, self.run_cargo(args))
 
     def determine_targets(self, settings, file_name):
         """Detect the target/filters needed to pass to Cargo to compile

tests/error-tests/benches/bench_err.rs

@@ -0,0 +1,6 @@
+// Can't have a regular bench because [feature(test)] is restricted
+// to nightly.
+
+#[asdf]
+// ^ERR The attribute `asdf` is currently unknown
+fn f() {}

tests/test_syntax_check.py

@@ -123,6 +123,7 @@ def test_messages(self):
             'multi-targets/src/lmod1.rs',
             'multi-targets/src/altmain.rs',
             'multi-targets/tests/common/helpers.rs',
+            'error-tests/benches/bench_err.rs',
             # "children" without spans
             'error-tests/tests/arg-count-mismatch.rs',
             # "children" with spans