granular build/namespaces categories

geoffviola · pre-commit-ci[bot] · web-flow · commit 26af9717305c · 2025-07-09T11:13:46.000-04:00
Enhance the using directives check by adding more granularity to the warnings.
The warnings are split into multiple categories
1. block/namespace scope
2. source/header file
3. literal/nonliteral namespace

Possible filter combinations would look like the following

1. Google: None
2. CppCoreGuidelines
    1. -build/namespaces/header/block
    2. -build/namespaces/source
3. Like CppCoreGuidlines, but disallow non-literal namespaces in source files at namespace scope
    1. -build/namespaces/header/block
    2. -build/namespaces/source/block
    3. -build/namespaces/source/namespace/literal

Co-authored-by: pre-commit-ci[bot] &lt;66853113+pre-commit-ci[bot]@users.noreply.github.com&gt;
diff --git a/cpplint.py b/cpplint.py
@@ -308,8 +308,14 @@
     "build/include_order",
     "build/include_what_you_use",
     "build/namespaces_headers",
-    "build/namespaces_literals",
-    "build/namespaces",
+    "build/namespaces/header/block/literals",
+    "build/namespaces/header/block/nonliterals",
+    "build/namespaces/header/namespace/literals",
+    "build/namespaces/header/namespace/nonliterals",
+    "build/namespaces/source/block/literals",
+    "build/namespaces/source/block/nonliterals",
+    "build/namespaces/source/namespace/literals",
+    "build/namespaces/source/namespace/nonliterals",
     "build/printf_format",
     "build/storage_class",
     "legal/copyright",
@@ -935,6 +941,16 @@
     "Missing space after ,": r"s/,\([^ ]\)/, \1/g",
 }
 
+# Used for backwards compatibility and ease of use
+_FILTER_SHORTCUTS = {
+    "build/namespaces_literals": [
+        "build/namespaces/header/block/literals",
+        "build/namespaces/header/namespace/literals",
+        "build/namespaces/source/block/literals",
+        "build/namespaces/source/namespace/literals",
+    ]
+}
+
 # The root directory used for deriving header guard CPP variable.
 # This is set by --root flag.
 _root = None
@@ -1457,7 +1473,12 @@ def AddFilters(self, filters):
         for filt in filters.split(","):
             clean_filt = filt.strip()
             if clean_filt:
-                self.filters.append(clean_filt)
+                if len(clean_filt) > 1 and clean_filt[1:] in _FILTER_SHORTCUTS:
+                    starting_char = clean_filt[0]
+                    new_filters = [starting_char + x for x in _FILTER_SHORTCUTS[clean_filt[1:]]]
+                    self.filters.extend(new_filters)
+                else:
+                    self.filters.append(clean_filt)
         for filt in self.filters:
             if not filt.startswith(("+", "-")):
                 msg = f"Every filter in --filters must start with + or - ({filt} does not)"
@@ -3287,6 +3308,14 @@ def InAsmBlock(self):
         """
         return self.stack and self.stack[-1].inline_asm != _NO_ASM
 
+    def InBlockScope(self):
+        """Check if we are currently one level inside a block scope.
+
+        Returns:
+          True if top of the stack is a block scope, False otherwise.
+        """
+        return len(self.stack) > 0 and not isinstance(self.stack[-1], _NamespaceInfo)
+
     def InTemplateArgumentList(self, clean_lines, linenum, pos):
         """Check if current position is inside template argument list.
 
@@ -6021,22 +6050,26 @@ def CheckLanguage(
         )
 
     if re.search(r"\busing namespace\b", line):
-        if re.search(r"\bliterals\b", line):
-            error(
-                filename,
-                linenum,
-                "build/namespaces_literals",
-                5,
-                "Do not use namespace using-directives.  Use using-declarations instead.",
-            )
-        else:
-            error(
-                filename,
-                linenum,
-                "build/namespaces",
-                5,
-                "Do not use namespace using-directives.  Use using-declarations instead.",
-            )
+        is_literals = re.search(r"\bliterals\b", line) is not None
+        is_header = not _IsSourceExtension(file_extension)
+        file_type = "header" if is_header else "source"
+
+        # Check for the block scope for multiline blocks.
+        # Check if the line starts with the using directive as a heuristic in case it's all one line
+        is_block_scope = nesting_state.InBlockScope() or not line.startswith("using namespace")
+
+        scope_type = "block" if is_block_scope else "namespace"
+        literal_type = "literals" if is_literals else "nonliterals"
+
+        specific_category = f"build/namespaces/{file_type}/{scope_type}/{literal_type}"
+
+        error(
+            filename,
+            linenum,
+            specific_category,
+            5,
+            "Do not use namespace using-directives.  Use using-declarations instead.",
+        )
 
     # Detect variable-length arrays.
     match = re.match(r"\s*(.+::)?(\w+) [a-z]\w*\[(.+)];", line)
diff --git a/cpplint_unittest.py b/cpplint_unittest.py
@@ -3640,7 +3640,7 @@ def DoTest(self, lines):
             assert (
                 error_collector.Results().count(
                     "Do not use namespace using-directives.  Use using-declarations instead.  "
-                    "[build/namespaces] [5]"
+                    "[build/namespaces/source/namespace/nonliterals] [5]"
                 )
                 == 1
             )
@@ -3649,20 +3649,6 @@ def DoTest(self, lines):
         DoTest(self, ["", "", "", "using namespace foo;"])
         DoTest(self, ["// hello", "using namespace foo;"])
 
-    def testUsingLiteralsNamespaces(self):
-        self.TestLint(
-            "using namespace std::literals;",
-            "Do not use namespace"
-            " using-directives.  Use using-declarations instead."
-            "  [build/namespaces_literals] [5]",
-        )
-        self.TestLint(
-            "using namespace std::literals::chrono_literals;",
-            "Do"
-            " not use namespace using-directives.  Use using-declarations instead."
-            "  [build/namespaces_literals] [5]",
-        )
-
     def testNewlineAtEOF(self):
         def DoTest(self, data, is_missing_eof):
             error_collector = ErrorCollector(self.assertTrue)
@@ -4203,6 +4189,73 @@ def testEndOfNamespaceComments(self):
             == 0
         )
 
+    def testUsingNamespacesGranular(self):
+        """Test granular using namespace checks for different contexts."""
+
+        self.TestLanguageRulesCheck(
+            "foo.h",
+            "using namespace std;",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/header/namespace/nonliterals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.h",
+            "using namespace std::chrono::literals;",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/header/namespace/literals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.cc",
+            "using namespace std;",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/source/namespace/nonliterals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.cc",
+            "using namespace std::chrono::literals;",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/source/namespace/literals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.h",
+            "{ using namespace std; }",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/header/block/nonliterals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.h",
+            "{ using namespace std::chrono::literals; }",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/header/block/literals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.cc",
+            "{ using namespace std; }",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/source/block/nonliterals] [5]",
+        )
+
+        self.TestLanguageRulesCheck(
+            "foo.cc",
+            "{ using namespace std::chrono::literals; }",
+            "Do not use namespace using-directives.  "
+            "Use using-declarations instead."
+            "  [build/namespaces/source/block/literals] [5]",
+        )
+
     def testComma(self):
         self.TestLint("a = f(1,2);", "Missing space after ,  [whitespace/comma] [3]")
         self.TestLint(
diff --git a/samples/silly-sample/filters.def b/samples/silly-sample/filters.def
@@ -13,7 +13,7 @@ src/sillycode.cpp:1:  Include the directory when naming header files  [build/inc
 src/sillycode.cpp:2:  <ratio> is an unapproved C++11 header.  [build/c++11] [5]
 src/sillycode.cpp:3:  Found C system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
 src/sillycode.cpp:4:  Found C system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
-src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces] [5]
+src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces/source/namespace/nonliterals] [5]
 src/sillycode.cpp:40:  If/else bodies with multiple statements require braces  [readability/braces] [4]
 src/sillycode.cpp:66:  Single-parameter constructors should be marked explicit.  [runtime/explicit] [4]
 src/sillycode.cpp:76:  Single-parameter constructors should be marked explicit.  [runtime/explicit] [4]
diff --git a/samples/silly-sample/includeorder_cfirst.def b/samples/silly-sample/includeorder_cfirst.def
@@ -11,7 +11,7 @@ src/sillycode.cpp:2:  Should have a space between // and comment  [whitespace/co
 src/sillycode.cpp:2:  <ratio> is an unapproved C++11 header.  [build/c++11] [5]
 src/sillycode.cpp:3:  Found other system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
 src/sillycode.cpp:4:  Found other system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
-src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces] [5]
+src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces/source/namespace/nonliterals] [5]
 src/sillycode.cpp:8:  public: should be indented +1 space inside class Date  [whitespace/indent] [3]
 src/sillycode.cpp:15:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
 src/sillycode.cpp:39:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
diff --git a/samples/silly-sample/sed.def b/samples/silly-sample/sed.def
@@ -15,7 +15,7 @@ sed -i '249s/\([^ ]\){/\1 {/' src/sillycode.cpp # Missing space before {  [white
 # src/sillycode.cpp:2:  "<ratio> is an unapproved C++11 header."  [build/c++11] [5]
 # src/sillycode.cpp:3:  "Found C system header after other header. Should be: sillycode.h, c system, c++ system, other."  [build/include_order] [4]
 # src/sillycode.cpp:4:  "Found C system header after other header. Should be: sillycode.h, c system, c++ system, other."  [build/include_order] [4]
-# src/sillycode.cpp:5:  "Do not use namespace using-directives.  Use using-declarations instead."  [build/namespaces] [5]
+# src/sillycode.cpp:5:  "Do not use namespace using-directives.  Use using-declarations instead."  [build/namespaces/source/namespace/nonliterals] [5]
 # src/sillycode.cpp:8:  "public: should be indented +1 space inside class Date"  [whitespace/indent] [3]
 # src/sillycode.cpp:15:  "{ should almost always be at the end of the previous line"  [whitespace/braces] [4]
 # src/sillycode.cpp:39:  "{ should almost always be at the end of the previous line"  [whitespace/braces] [4]
diff --git a/samples/silly-sample/simple.def b/samples/silly-sample/simple.def
@@ -12,7 +12,7 @@ src/sillycode.cpp:2:  Should have a space between // and comment  [whitespace/co
 src/sillycode.cpp:2:  <ratio> is an unapproved C++11 header.  [build/c++11] [5]
 src/sillycode.cpp:3:  Found C system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
 src/sillycode.cpp:4:  Found C system header after other header. Should be: sillycode.h, c system, c++ system, other.  [build/include_order] [4]
-src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces] [5]
+src/sillycode.cpp:5:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces/source/namespace/nonliterals] [5]
 src/sillycode.cpp:8:  public: should be indented +1 space inside class Date  [whitespace/indent] [3]
 src/sillycode.cpp:15:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
 src/sillycode.cpp:39:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
