[clang-tools-extra] [clang-tidy] Option to ignore anonymous namespaces in avoid-non-const-global-variables (PR #93827)
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Thu May 30 07:08:40 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tidy
Author: Pascal Jungblut (pascalj)
<details>
<summary>Changes</summary>
Add an option to ignore warnings for cppcoreguidelines avoid-non-const-global-variables.
Understandably, the core guidelines discourage non const global variables, even at the TU level (see https://github.com/isocpp/CppCoreGuidelines/issues/2195). However, having a small TU with an interface that uses a non const variable from an anonymous namespace can be a valid choice.
This adds an option that disables the warning just for anonymous namespaces, i.e. at the file level. The default is still to show a warning, just as before.
---
Patch is 36.15 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/93827.diff
3 Files Affected:
- (modified) clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp (+4-2)
- (modified) clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst (+22)
- (modified) clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp (+92-45)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
index ee17b0e014288..b536016a3cccd 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
+++ b/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,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst
index 21c20af6e8107..e2350872c6ece 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst
+++ b/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`.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp
index 3ca1029433d22..8956dd414356e 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp
@@ -1,21 +1,30 @@
-// RUN: %check_clang_tidy %s cppcoreguidelines-avoid-non-const-global-variables %t
+// RUN: %check_clang_tidy %s -check-suffix=DEFAULT cppcoreguidelines-avoid-non-const-global-variables %t
+// RUN: %check_clang_tidy %s -check-suffix=NAMESPACE cppcoreguidelines-avoid-non-const-global-variables %t -- \
+// RUN: -config="{CheckOptions: {cppcoreguidelines-avoid-non-const-global-variables.AllowAnonymousNamespace : 'true'}}"
+
int nonConstInt = 0;
-// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'nonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:5: warning: variable 'nonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:5: warning: variable 'nonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
int &nonConstIntReference = nonConstInt;
-// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: variable 'nonConstIntReference' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:6: warning: variable 'nonConstIntReference' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:6: warning: variable 'nonConstIntReference' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
int *pointerToNonConstInt = &nonConstInt;
-// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: variable 'pointerToNonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
-// CHECK-MESSAGES: :[[@LINE-2]]:6: warning: variable 'pointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:6: warning: variable 'pointerToNonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:6: warning: variable 'pointerToNonConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-3]]:6: warning: variable 'pointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-4]]:6: warning: variable 'pointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
int *const constPointerToNonConstInt = &nonConstInt;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'constPointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'constPointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'constPointerToNonConstInt' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
namespace namespace_name {
int nonConstNamespaceInt = 0;
-// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'nonConstNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:5: warning: variable 'nonConstNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:5: warning: variable 'nonConstNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
const int constNamespaceInt = 0;
} // namespace namespace_name
@@ -23,7 +32,8 @@ const int constNamespaceInt = 0;
const int constInt = 0;
const int *pointerToConstInt = &constInt;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'pointerToConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'pointerToConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'pointerToConstInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
const int *const constPointerToConstInt = &constInt;
@@ -38,7 +48,8 @@ int function() {
namespace {
int nonConstAnonymousNamespaceInt = 0;
-// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'nonConstAnonymousNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:5: warning: variable 'nonConstAnonymousNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE-NOT: :[[@LINE-2]]:5: warning: variable 'nonConstAnonymousNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
} // namespace
class DummyClass {
@@ -52,28 +63,37 @@ class DummyClass {
};
DummyClass nonConstClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'nonConstClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'nonConstClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'nonConstClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
DummyClass *pointerToNonConstDummyClass = &nonConstClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: variable 'pointerToNonConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
-// CHECK-MESSAGES: :[[@LINE-2]]:13: warning: variable 'pointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:13: warning: variable 'pointerToNonConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:13: warning: variable 'pointerToNonConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-3]]:13: warning: variable 'pointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-4]]:13: warning: variable 'pointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
DummyClass &referenceToNonConstDummyClass = nonConstClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: variable 'referenceToNonConstDummyClass' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:13: warning: variable 'referenceToNonConstDummyClass' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:13: warning: variable 'referenceToNonConstDummyClass' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
int *nonConstPointerToMember = &nonConstClassInstance.nonConstPublicMemberVariable;
-// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: variable 'nonConstPointerToMember' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
-// CHECK-MESSAGES: :[[@LINE-2]]:6: warning: variable 'nonConstPointerToMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:6: warning: variable 'nonConstPointerToMember' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:6: warning: variable 'nonConstPointerToMember' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-3]]:6: warning: variable 'nonConstPointerToMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-4]]:6: warning: variable 'nonConstPointerToMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
int *const constPointerToNonConstMember = &nonConstClassInstance.nonConstPublicMemberVariable;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'constPointerToNonConstMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'constPointerToNonConstMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'constPointerToNonConstMember' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
const DummyClass constClassInstance;
DummyClass *const constPointerToNonConstDummyClass = &nonConstClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:19: warning: variable 'constPointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:19: warning: variable 'constPointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:19: warning: variable 'constPointerToNonConstDummyClass' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
const DummyClass *nonConstPointerToConstDummyClass = &constClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:19: warning: variable 'nonConstPointerToConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:19: warning: variable 'nonConstPointerToConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:19: warning: variable 'nonConstPointerToConstDummyClass' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
const DummyClass *const constPointerToConstDummyClass = &constClassInstance;
@@ -83,7 +103,8 @@ const DummyClass &constReferenceToDummyClass = constClassInstance;
namespace namespace_name {
DummyClass nonConstNamespaceClassInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'nonConstNamespaceClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'nonConstNamespaceClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'nonConstNamespaceClassInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
const DummyClass constDummyClassInstance;
} // namespace namespace_name
@@ -95,22 +116,28 @@ enum DummyEnum {
};
DummyEnum nonConstDummyEnumInstance = DummyEnum::first;
-// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: variable 'nonConstDummyEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:11: warning: variable 'nonConstDummyEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:11: warning: variable 'nonConstDummyEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
DummyEnum *pointerToNonConstDummyEnum = &nonConstDummyEnumInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'pointerToNonConstDummyEnum' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
-// CHECK-MESSAGES: :[[@LINE-2]]:12: warning: variable 'pointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'pointerToNonConstDummyEnum' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'pointerToNonConstDummyEnum' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-3]]:12: warning: variable 'pointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-4]]:12: warning: variable 'pointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
DummyEnum &referenceToNonConstDummyEnum = nonConstDummyEnumInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: variable 'referenceToNonConstDummyEnum' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:12: warning: variable 'referenceToNonConstDummyEnum' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:12: warning: variable 'referenceToNonConstDummyEnum' provides global access to a non-const object; consider making the referenced data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
DummyEnum *const constPointerToNonConstDummyEnum = &nonConstDummyEnumInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:18: warning: variable 'constPointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-DEFAULT: [[@LINE-1]]:18: warning: variable 'constPointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
+// CHECK-MESSAGES-NAMESPACE: [[@LINE-2]]:18: warning: variable 'constPointerToNonConstDummyEnum' provides global access to a non-const object; consider making the pointed-to data 'const' [cppcoreguidelines-avoid-non-const-global-variables]
const DummyEnum constDummyEnumInstance = DummyEnum::first;
const DummyEnum *nonConstPointerToConstDummyEnum = &constDummyEnumInstance;
-// CHECK-MESSAGES: :[[@LINE-1]]:18: warning: variable 'nonConstPointerToConstDummyEnum' is non-const and globally accessible, consider making it const [c...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/93827
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