ament_clang_tidy - Fix Reporting when WarningsAsErrors is specified i…

…n config (#397)

* feature

Signed-off-by: Matt Condino <mwcondino@gmail.com>

ament_clang_tidy/ament_clang_tidy/main.py

@@ -173,6 +173,9 @@ def start_subprocess(full_cmd):
                 print('The invocation of "%s" failed with error code %d: %s' %
                       (os.path.basename(clang_tidy_bin), e.returncode, e),
                       file=sys.stderr)
+                # Attempt to recover output, if any was found (eg - if
+                # WarningsAsErrors was specified in the config file).
+                output = e.output.decode('utf-8')
             return output
 
         files = []