Fix flag<>targets warning

#82

Author: cpsauer

refresh.template.py

@@ -799,8 +799,11 @@ def _get_commands(target: str, flags: str):
 
     additional_flags = shlex.split(flags) + sys.argv[1:]
 
-    # Detect any positional args--build targets--in the flags, and issue a warning.
-    if not all(f.startswith('-') for f in additional_flags) or '--' in additional_flags[:-1]:
+    # Detect anything that looks like a build target in the flags, and issue a warning.
+    # Note that positional arguments after -- are all interpreted as target patterns. (If it's at the end, then no worries.)
+    # And that we have to look for targets. checking for a - prefix is not enough. Consider the case of `-c opt` leading to a false positive
+    if ('--' in additional_flags[:-1]
+        or any(re.match(r'-?(@|:|//)', f) for f in additional_flags)):
         log_warning(""">>> The flags you passed seem to contain targets.
     Try adding them as targets in your refresh_compile_commands rather than flags.
     [Specifying targets at runtime isn't supported yet, and in a moment, Bazel will likely fail to parse without our help. If you need to be able to specify targets at runtime, and can't easily just add them to your refresh_compile_commands, please open an issue or file a PR. You may also want to refer to https://github.com/hedronvision/bazel-compile-commands-extractor/issues/62.]""")