Add option to ignore anonymous namespaces in avoid-non-const-global-variables

Author: pascalj

clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "AvoidNonConstGlobalVariablesCheck.h"
-#include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 
@@ -16,9 +15,12 @@ using namespace clang::ast_matchers;
 namespace clang::tidy::cppcoreguidelines {
 
 void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {
+  auto NamespaceMatcher = Options.get("AllowAnonymousNamespace", false)
+                              ? namespaceDecl(unless(isAnonymous()))
+                              : namespaceDecl();
   auto GlobalContext =
       varDecl(hasGlobalStorage(),
-              hasDeclContext(anyOf(namespaceDecl(), translationUnitDecl())));
+              hasDeclContext(anyOf(NamespaceMatcher, translationUnitDecl())));
 
   auto GlobalVariable = varDecl(
       GlobalContext,

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst

@@ -41,3 +41,25 @@ The variables ``a``, ``c``, ``c_ptr1``, ``c_const_ptr`` and ``c_reference``
 will all generate warnings since they are either a non-const globally accessible
 variable, a pointer or a reference providing global access to non-const data
 or both.
+
+Options
+-------
+
+.. option:: AllowAnonymousNamespace
+
+   When set to `true` (default is `false`), non-const variables in anonymous namespaces will not generate a warning.
+
+Example
+^^^^^^^
+
+.. code-block:: c++
+
+   namespace {
+     int counter = 0;
+   }
+
+   int Increment() {
+    return ++counter;
+   }
+
+will not generate a warning for `counter` if :option:`AllowAnonymousNamespace` is set to `true`.