"using namespace std::placeholders;" should also be valid

Author: calcmogul

wpiformat/test/test_usingnamespacestd.py

@@ -51,6 +51,11 @@ def test_usingnamespacestd():
                    "using namespace std::chrono_literals;" + os.linesep))
     outputs.append(("", False, True))
 
+    # Ignore std::placeholders
+    inputs.append(("./Main.cpp",
+                   "using namespace std::placeholders;" + os.linesep))
+    outputs.append(("", False, True))
+
     assert len(inputs) == len(outputs)
 
     config_file = Config(os.path.abspath(os.getcwd()), ".styleguide")

wpiformat/wpiformat/usingnamespacestd.py

@@ -16,7 +16,7 @@ def run_pipeline(self, config_file, name, lines):
         # Find instances of "using namespace std;" or subnamespaces of "std",
         # but not std::literals or std::chrono_literals.
         regex = re.compile(
-            "using\s+namespace\s+std(;|::(?!(chrono_)?literals))")
+            "using\s+namespace\s+std(;|::(?!(chrono_)?literals|placeholders))")
 
         for match in re.finditer(regex, lines):
             linenum = lines.count(linesep, 0, match.start()) + 1