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[clang-tidy] Option to ignore anonymous namespaces in avoid-non-const-global-variables #93827

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Merged
merged 2 commits into from
Jul 1, 2024
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[clang-tidy] Option to ignore anonymous namespaces in avoid-non-const-global-variables #93827

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abe862b
Add option to ignore anonymous namespaces in avoid-non-const-global-v…
pascalj May 30, 2024
d89c1b2
Merge branch 'main' into main
PiotrZSL Jul 1, 2024
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19 changes: 16 additions & 3 deletions clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7,21 +7,30 @@
//===----------------------------------------------------------------------===//

#include "AvoidNonConstGlobalVariablesCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"

using namespace clang::ast_matchers;

namespace clang::tidy::cppcoreguidelines {

AvoidNonConstGlobalVariablesCheck::AvoidNonConstGlobalVariablesCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
AllowInternalLinkage(Options.get("AllowInternalLinkage", false)) {}
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Option name could be a constant to avoid duplication.


void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {
auto NamespaceMatcher = AllowInternalLinkage
? namespaceDecl(unless(isAnonymous()))
: namespaceDecl();
auto GlobalContext =
varDecl(hasGlobalStorage(),
hasDeclContext(anyOf(namespaceDecl(), translationUnitDecl())));
hasDeclContext(anyOf(NamespaceMatcher, translationUnitDecl())));

auto GlobalVariable = varDecl(
GlobalContext,
AllowInternalLinkage ? varDecl(unless(isStaticStorageClass()))
: varDecl(),
unless(anyOf(
isConstexpr(), hasType(isConstQualified()),
hasType(referenceType())))); // References can't be changed, only the
Expand All @@ -43,7 +52,6 @@ void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {

void AvoidNonConstGlobalVariablesCheck::check(
const MatchFinder::MatchResult &Result) {

if (const auto *Variable =
Result.Nodes.getNodeAs<VarDecl>("non-const_variable")) {
diag(Variable->getLocation(), "variable %0 is non-const and globally "
Expand All @@ -63,4 +71,9 @@ void AvoidNonConstGlobalVariablesCheck::check(
}
}

void AvoidNonConstGlobalVariablesCheck::storeOptions(
ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AllowInternalLinkage", AllowInternalLinkage);
}

} // namespace clang::tidy::cppcoreguidelines
7 changes: 5 additions & 2 deletions clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.h
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Expand Up @@ -20,10 +20,13 @@ namespace clang::tidy::cppcoreguidelines {
/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.html
class AvoidNonConstGlobalVariablesCheck : public ClangTidyCheck {
public:
AvoidNonConstGlobalVariablesCheck(StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context) {}
AvoidNonConstGlobalVariablesCheck(StringRef Name, ClangTidyContext *Context);
void registerMatchers(ast_matchers::MatchFinder *Finder) override;
void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
void storeOptions(ClangTidyOptions::OptionMap &Opts) override;

private:
const bool AllowInternalLinkage;
};

} // namespace clang::tidy::cppcoreguidelines
Expand Down
5 changes: 5 additions & 0 deletions clang-tools-extra/docs/ReleaseNotes.rst
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Expand Up @@ -269,6 +269,11 @@ Changes in existing checks
<clang-tidy/checks/bugprone/use-after-move>` check to also handle
calls to ``std::forward``.

- Improved :doc:`cppcoreguidelines-avoid-non-const-global-variables
<clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables>` check
with a new option `AllowInternalLinkage` to disable the warning for variables
with internal linkage.

- Improved :doc:`cppcoreguidelines-macro-usage
<clang-tidy/checks/cppcoreguidelines/macro-usage>` check by ignoring macro with
hash preprocessing token.
Expand Down
8 changes: 8 additions & 0 deletions ...a/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst
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Expand Up @@ -41,3 +41,11 @@ 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:: AllowInternalLinkage

When set to `true`, static non-const variables and variables in anonymous
namespaces will not generate a warning. The default value is `false`.
22 changes: 17 additions & 5 deletions ...ols-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-non-const-global-variables.cpp
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FYI: You could remove the explicit check-nots here:

// RUN: %check_clang_tidy %s -check-suffixes=,INTERNAL-LINKAGE cppcoreguidelines-avoid-non-const-global-variables %t
// RUN: %check_clang_tidy %s cppcoreguidelines-avoid-non-const-global-variables %t -- \
// RUN: -config="{CheckOptions: {cppcoreguidelines-avoid-non-const-global-variables.AllowInternalLinkage : 'true'}}"


namespace {
int nonConstAnonymousNamespaceInt = 0;
// CHECK-MESSAGES-INTERNAL-LINKAGE: :[[@LINE-1]]:5: warning: variable 'nonConstAnonymousNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
} // namespace

(There are also two check-nots where the line is off by one)

Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
// RUN: %check_clang_tidy %s cppcoreguidelines-avoid-non-const-global-variables %t
// RUN: %check_clang_tidy %s -check-suffixes=,DEFAULT cppcoreguidelines-avoid-non-const-global-variables %t
// RUN: %check_clang_tidy %s -check-suffixes=,INTERNAL-LINKAGE cppcoreguidelines-avoid-non-const-global-variables %t -- \
// RUN: -config="{CheckOptions: {cppcoreguidelines-avoid-non-const-global-variables.AllowInternalLinkage : '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]
Expand Down Expand Up @@ -38,9 +40,16 @@ 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-INTERNAL-LINKAGE-NOT: :[[@LINE-2]]:5: warning: variable 'nonConstAnonymousNamespaceInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
} // namespace

static int nonConstStaticInt = 0;
// CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:12: warning: variable 'nonConstStaticInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-INTERNAL-LINKAGE-NOT: :[[@LINE-2]]:12: warning: variable 'nonConstStaticInt' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]

static const int constStaticInt = 0;

class DummyClass {
public:
int nonConstPublicMemberVariable = 0;
Expand Down Expand Up @@ -126,7 +135,8 @@ const DummyEnum constNamespaceEnumInstance = DummyEnum::first;
namespace {
DummyEnum nonConstAnonymousNamespaceEnumInstance = DummyEnum::first;
}
// CHECK-MESSAGES: :[[@LINE-2]]:11: warning: variable 'nonConstAnonymousNamespaceEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-DEFAULT: :[[@LINE-2]]:11: warning: variable 'nonConstAnonymousNamespaceEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-INTERNAL-LINKAGE-NOT: :[[@LINE-2]]:11: warning: variable 'nonConstAnonymousNamespaceEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]

// CHECKING FOR NON-CONST GLOBAL STRUCT ///////////////////////////////////////
struct DummyStruct {
Expand Down Expand Up @@ -169,7 +179,8 @@ const DummyStruct constNamespaceDummyStructInstance;
namespace {
DummyStruct nonConstAnonymousNamespaceStructInstance;
}
// CHECK-MESSAGES: :[[@LINE-2]]:13: warning: variable 'nonConstAnonymousNamespaceStructInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-DEFAULT: :[[@LINE-2]]:13: warning: variable 'nonConstAnonymousNamespaceStructInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-INTERNAL-LINKAGE-NOT: :[[@LINE-2]]:11: warning: variable 'nonConstAnonymousNamespaceEnumInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]

// CHECKING FOR NON-CONST GLOBAL UNION ////////////////////////////////////////
union DummyUnion {
Expand Down Expand Up @@ -209,7 +220,8 @@ const DummyUnion constNamespaceDummyUnionInstance = {0x0};
namespace {
DummyUnion nonConstAnonymousNamespaceUnionInstance = {0x0};
}
// CHECK-MESSAGES: :[[@LINE-2]]:12: warning: variable 'nonConstAnonymousNamespaceUnionInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-DEFAULT: :[[@LINE-2]]:12: warning: variable 'nonConstAnonymousNamespaceUnionInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]
// CHECK-MESSAGES-INTERNAL-LINKAGE-NOT: :[[@LINE-3]]:12: warning: variable 'nonConstAnonymousNamespaceUnionInstance' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]

// CHECKING FOR NON-CONST GLOBAL FUNCTION POINTER /////////////////////////////
int dummyFunction() {
Expand Down
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