[clang-tools-extra] [clang-tidy] support pointee mutation check in misc-const-correctness (PR #130492)
Congcong Cai via cfe-commits
cfe-commits at lists.llvm.org
Sun Mar 9 08:57:26 PDT 2025
https://github.com/HerrCai0907 created https://github.com/llvm/llvm-project/pull/130492
None
>From 87bda4d0f9c87512f42a600599dd65b80d8e7f60 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Sun, 9 Mar 2025 15:43:37 +0000
Subject: [PATCH] [clang-tidy] support pointee mutation check in
misc-const-correctness
---
.../clang-tidy/misc/ConstCorrectnessCheck.cpp | 158 ++++++++++++------
.../clang-tidy/misc/ConstCorrectnessCheck.h | 3 +
clang-tools-extra/docs/ReleaseNotes.rst | 3 +-
.../checks/misc/const-correctness.rst | 44 +++++
.../const-correctness-pointer-as-pointers.cpp | 50 ++++++
.../const-correctness-transform-values.cpp | 1 +
.../const-correctness-values-before-cxx23.cpp | 1 +
.../misc/const-correctness-values.cpp | 1 +
.../misc/const-correctness-wrong-config.cpp | 7 +-
9 files changed, 209 insertions(+), 59 deletions(-)
create mode 100644 clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-pointer-as-pointers.cpp
diff --git a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
index 6e412e576e5f9..523dfbfd06138 100644
--- a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
@@ -13,6 +13,8 @@
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
+#include "llvm/Support/Casting.h"
+#include <cassert>
using namespace clang::ast_matchers;
@@ -39,34 +41,47 @@ ConstCorrectnessCheck::ConstCorrectnessCheck(StringRef Name,
: ClangTidyCheck(Name, Context),
AnalyzeValues(Options.get("AnalyzeValues", true)),
AnalyzeReferences(Options.get("AnalyzeReferences", true)),
+ AnalyzePointers(Options.get("AnalyzePointers", true)),
WarnPointersAsValues(Options.get("WarnPointersAsValues", false)),
+ WarnPointersAsPointers(Options.get("WarnPointersAsPointers", true)),
TransformValues(Options.get("TransformValues", true)),
TransformReferences(Options.get("TransformReferences", true)),
TransformPointersAsValues(
Options.get("TransformPointersAsValues", false)),
+ TransformPointersAsPointers(
+ Options.get("TransformPointersAsPointers", true)),
AllowedTypes(
utils::options::parseStringList(Options.get("AllowedTypes", ""))) {
- if (AnalyzeValues == false && AnalyzeReferences == false)
+ if (AnalyzeValues == false && AnalyzeReferences == false &&
+ AnalyzePointers == false)
this->configurationDiag(
"The check 'misc-const-correctness' will not "
- "perform any analysis because both 'AnalyzeValues' and "
- "'AnalyzeReferences' are false.");
+ "perform any analysis because both 'AnalyzeValues', "
+ "'AnalyzeReferences' and 'AnalyzePointers' are false.");
}
void ConstCorrectnessCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AnalyzeValues", AnalyzeValues);
Options.store(Opts, "AnalyzeReferences", AnalyzeReferences);
+ Options.store(Opts, "AnalyzePointers", AnalyzePointers);
Options.store(Opts, "WarnPointersAsValues", WarnPointersAsValues);
+ Options.store(Opts, "WarnPointersAsPointers", WarnPointersAsPointers);
Options.store(Opts, "TransformValues", TransformValues);
Options.store(Opts, "TransformReferences", TransformReferences);
Options.store(Opts, "TransformPointersAsValues", TransformPointersAsValues);
+ Options.store(Opts, "TransformPointersAsPointers",
+ TransformPointersAsPointers);
Options.store(Opts, "AllowedTypes",
utils::options::serializeStringList(AllowedTypes));
}
void ConstCorrectnessCheck::registerMatchers(MatchFinder *Finder) {
- const auto ConstType = hasType(isConstQualified());
+ const auto ConstType = hasType(
+ qualType(isConstQualified(),
+ // pointee check will check the const pointer and const array
+ unless(pointerType()), unless(arrayType())));
+
const auto ConstReference = hasType(references(isConstQualified()));
const auto RValueReference = hasType(
referenceType(anyOf(rValueReferenceType(), unless(isSpelledAsLValue()))));
@@ -124,6 +139,11 @@ void ConstCorrectnessCheck::check(const MatchFinder::MatchResult &Result) {
const auto *LocalScope = Result.Nodes.getNodeAs<Stmt>("scope");
const auto *Variable = Result.Nodes.getNodeAs<VarDecl>("local-value");
const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("function-decl");
+ const auto *VarDeclStmt = Result.Nodes.getNodeAs<DeclStmt>("decl-stmt");
+ // It can not be guaranteed that the variable is declared isolated,
+ // therefore a transformation might effect the other variables as well and
+ // be incorrect.
+ const bool CanBeFixIt = VarDeclStmt != nullptr && VarDeclStmt->isSingleDecl();
/// If the variable was declared in a template it might be analyzed multiple
/// times. Only one of those instantiations shall emit a warning. NOTE: This
@@ -147,64 +167,92 @@ void ConstCorrectnessCheck::check(const MatchFinder::MatchResult &Result) {
}
}
- // Each variable can only be in one category: Value, Pointer, Reference.
- // Analysis can be controlled for every category.
- if (VC == VariableCategory::Reference && !AnalyzeReferences)
- return;
-
- if (VC == VariableCategory::Reference &&
- Variable->getType()->getPointeeType()->isPointerType() &&
- !WarnPointersAsValues)
- return;
-
- if (VC == VariableCategory::Pointer && !WarnPointersAsValues)
- return;
-
- if (VC == VariableCategory::Value && !AnalyzeValues)
- return;
-
- // The scope is only registered if the analysis shall be run.
- registerScope(LocalScope, Result.Context);
-
- // Offload const-analysis to utility function.
- if (ScopesCache[LocalScope]->isMutated(Variable))
- return;
-
- auto Diag = diag(Variable->getBeginLoc(),
- "variable %0 of type %1 can be declared 'const'")
- << Variable << Variable->getType();
- if (IsNormalVariableInTemplate)
- TemplateDiagnosticsCache.insert(Variable->getBeginLoc());
+ auto CheckValue = [&]() {
+ // The scope is only registered if the analysis shall be run.
+ registerScope(LocalScope, Result.Context);
+
+ // Offload const-analysis to utility function.
+ if (ScopesCache[LocalScope]->isMutated(Variable))
+ return;
+
+ auto Diag = diag(Variable->getBeginLoc(),
+ "variable %0 of type %1 can be declared 'const'")
+ << Variable << Variable->getType();
+ if (IsNormalVariableInTemplate)
+ TemplateDiagnosticsCache.insert(Variable->getBeginLoc());
+ if (!CanBeFixIt)
+ return;
+ using namespace utils::fixit;
+ if (VC == VariableCategory::Value && TransformValues) {
+ Diag << addQualifierToVarDecl(*Variable, *Result.Context,
+ Qualifiers::Const, QualifierTarget::Value,
+ QualifierPolicy::Right);
+ // FIXME: Add '{}' for default initialization if no user-defined default
+ // constructor exists and there is no initializer.
+ return;
+ }
- const auto *VarDeclStmt = Result.Nodes.getNodeAs<DeclStmt>("decl-stmt");
+ if (VC == VariableCategory::Reference && TransformReferences) {
+ Diag << addQualifierToVarDecl(*Variable, *Result.Context,
+ Qualifiers::Const, QualifierTarget::Value,
+ QualifierPolicy::Right);
+ return;
+ }
- // It can not be guaranteed that the variable is declared isolated, therefore
- // a transformation might effect the other variables as well and be incorrect.
- if (VarDeclStmt == nullptr || !VarDeclStmt->isSingleDecl())
- return;
+ if (VC == VariableCategory::Pointer && TransformPointersAsValues) {
+ Diag << addQualifierToVarDecl(*Variable, *Result.Context,
+ Qualifiers::Const, QualifierTarget::Value,
+ QualifierPolicy::Right);
+ return;
+ }
+ };
+
+ auto CheckPointee = [&]() {
+ assert(VC == VariableCategory::Pointer);
+ registerScope(LocalScope, Result.Context);
+ if (ScopesCache[LocalScope]->isPointeeMutated(Variable))
+ return;
+ auto Diag = diag(Variable->getBeginLoc(),
+ "variable %0 of type %1 can be declared 'const'")
+ << Variable << Variable->getType();
+ if (IsNormalVariableInTemplate)
+ TemplateDiagnosticsCache.insert(Variable->getBeginLoc());
+ if (!CanBeFixIt)
+ return;
+ using namespace utils::fixit;
+ if (TransformPointersAsPointers) {
+ Diag << addQualifierToVarDecl(*Variable, *Result.Context,
+ Qualifiers::Const, QualifierTarget::Pointee,
+ QualifierPolicy::Right);
+ }
+ };
- using namespace utils::fixit;
- if (VC == VariableCategory::Value && TransformValues) {
- Diag << addQualifierToVarDecl(*Variable, *Result.Context, Qualifiers::Const,
- QualifierTarget::Value,
- QualifierPolicy::Right);
- // FIXME: Add '{}' for default initialization if no user-defined default
- // constructor exists and there is no initializer.
+ // Each variable can only be in one category: Value, Pointer, Reference.
+ // Analysis can be controlled for every category.
+ if (VC == VariableCategory::Value && AnalyzeValues) {
+ CheckValue();
return;
}
-
- if (VC == VariableCategory::Reference && TransformReferences) {
- Diag << addQualifierToVarDecl(*Variable, *Result.Context, Qualifiers::Const,
- QualifierTarget::Value,
- QualifierPolicy::Right);
+ if (VC == VariableCategory::Reference && AnalyzeReferences) {
+ if (Variable->getType()->getPointeeType()->isPointerType() &&
+ !WarnPointersAsValues)
+ return;
+ CheckValue();
return;
}
-
- if (VC == VariableCategory::Pointer) {
- if (WarnPointersAsValues && TransformPointersAsValues) {
- Diag << addQualifierToVarDecl(*Variable, *Result.Context,
- Qualifiers::Const, QualifierTarget::Value,
- QualifierPolicy::Right);
+ if (VC == VariableCategory::Pointer && AnalyzePointers) {
+ const QualType VT = Variable->getType();
+ if (WarnPointersAsValues && !VT.isConstQualified())
+ CheckValue();
+ if (WarnPointersAsPointers) {
+ if (const auto *PT = dyn_cast<PointerType>(VT))
+ if (!PT->getPointeeType().isConstQualified())
+ CheckPointee();
+ if (const auto *AT = dyn_cast<ArrayType>(VT))
+ if (!AT->getElementType().isConstQualified()) {
+ assert(AT->getElementType()->isPointerType());
+ CheckPointee();
+ }
}
return;
}
diff --git a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.h b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.h
index 87dddc4faf781..a2dcaff1a2b61 100644
--- a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.h
+++ b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.h
@@ -40,11 +40,14 @@ class ConstCorrectnessCheck : public ClangTidyCheck {
const bool AnalyzeValues;
const bool AnalyzeReferences;
+ const bool AnalyzePointers;
const bool WarnPointersAsValues;
+ const bool WarnPointersAsPointers;
const bool TransformValues;
const bool TransformReferences;
const bool TransformPointersAsValues;
+ const bool TransformPointersAsPointers;
const std::vector<StringRef> AllowedTypes;
};
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 951b7f20af4c8..8d369f6b790e4 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -126,7 +126,8 @@ Changes in existing checks
<clang-tidy/checks/misc/const-correctness>` check by adding the option
`AllowedTypes`, that excludes specified types from const-correctness
checking and fixing false positives when modifying variant by ``operator[]``
- with template in parameters.
+ with template in parameters and supporting to check pointee mutation by
+ `AnalyzePointers` option.
- Improved :doc:`misc-redundant-expression
<clang-tidy/checks/misc/redundant-expression>` check by providing additional
diff --git a/clang-tools-extra/docs/clang-tidy/checks/misc/const-correctness.rst b/clang-tools-extra/docs/clang-tidy/checks/misc/const-correctness.rst
index 2e7e0f3602ab9..1950437fdd41a 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/misc/const-correctness.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/misc/const-correctness.rst
@@ -110,6 +110,13 @@ Options
// No warning
int const& ref = i;
+.. option:: AnalyzePointers
+
+ Enable or disable the analysis of pointers variables, like
+ ``int *ptr = &i;``. For specific checks, see options
+ `WarnPointersAsValues` and `WarnPointersAsPointers`.
+ Default is `true`.
+
.. option:: WarnPointersAsValues
This option enables the suggestion for ``const`` of the pointer itself.
@@ -125,6 +132,22 @@ Options
// No warning
const int *const pointer_variable = &value;
+.. option:: WarnPointersAsPointers
+
+ This option enables the suggestion for ``const`` of the value pointing.
+ Default is `true`.
+
+ Requires 'AnalyzePointers' to be 'true'.
+
+ .. code-block:: c++
+
+ int value = 42;
+
+ // No warning
+ const int *const pointer_variable = &value;
+ // Warning
+ int *const pointer_variable = &value;
+
.. option:: TransformValues
Provides fixit-hints for value types that automatically add ``const`` if
@@ -200,6 +223,27 @@ Options
int *changing_pointee = &value;
changing_pointee = &result;
+.. option:: TransformPointersAsPointers
+
+ Provides fixit-hints for pointers if the value it pointing to is not changed.
+ Default is `false`.
+
+ Requires 'WarnPointersAsPointers' to be 'true'.
+
+ .. code-block:: c++
+
+ int value = 42;
+
+ // Before
+ int * pointer_variable = &value;
+ // After
+ const int * pointer_variable = &value;
+
+ // Before
+ int * a[] = {&value, &value};
+ // After
+ const int * a[] = {&value, &value};
+
.. option:: AllowedTypes
A semicolon-separated list of names of types that will be excluded from
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-pointer-as-pointers.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-pointer-as-pointers.cpp
new file mode 100644
index 0000000000000..ec881da2f7b71
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-pointer-as-pointers.cpp
@@ -0,0 +1,50 @@
+// RUN: %check_clang_tidy %s misc-const-correctness %t \
+// RUN: -config='{CheckOptions: {\
+// RUN: misc-const-correctness.AnalyzeValues: false,\
+// RUN: misc-const-correctness.AnalyzeReferences: false,\
+// RUN: misc-const-correctness.AnalyzePointers: true,\
+// RUN: misc-const-correctness.WarnPointersAsValues: false,\
+// RUN: misc-const-correctness.WarnPointersAsPointers: true,\
+// RUN: misc-const-correctness.TransformPointersAsValues: false,\
+// RUN: misc-const-correctness.TransformPointersAsPointers: true\
+// RUN: }}' \
+// RUN: -- -fno-delayed-template-parsing
+
+void pointee_to_const() {
+ int a[] = {1, 2};
+ int *p_local0 = &a[0];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int *' can be declared 'const'
+ // CHECK-FIXES: int const*p_local0
+ p_local0 = &a[1];
+}
+
+void array_of_pointer_to_const() {
+ int a[] = {1, 2};
+ int *p_local0[1] = {&a[0]};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int *[1]' can be declared 'const'
+ // CHECK-FIXES: int const*p_local0[1]
+ p_local0[0] = &a[1];
+}
+
+template<class T>
+void template_fn() {
+ T a[] = {1, 2};
+ T *p_local0 = &a[0];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'char *' can be declared 'const'
+ // CHECK-FIXES: T const*p_local0
+ p_local0 = &a[1];
+}
+
+void instantiate() {
+ template_fn<char>();
+ template_fn<int>();
+ template_fn<char const>();
+}
+
+using const_int = int const;
+void ignore_const_alias() {
+ const_int a[] = {1, 2};
+ const_int *p_local0 = &a[0];
+ p_local0 = &a[1];
+}
+
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-transform-values.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-transform-values.cpp
index 109eddc195558..190d8ecec4c59 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-transform-values.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-transform-values.cpp
@@ -2,6 +2,7 @@
// RUN: -config="{CheckOptions: {\
// RUN: misc-const-correctness.TransformValues: true,\
// RUN: misc-const-correctness.WarnPointersAsValues: false, \
+// RUN: misc-const-correctness.WarnPointersAsPointers: false, \
// RUN: misc-const-correctness.TransformPointersAsValues: false} \
// RUN: }" -- -fno-delayed-template-parsing
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values-before-cxx23.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values-before-cxx23.cpp
index 3547ec080911e..af626255d9455 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values-before-cxx23.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values-before-cxx23.cpp
@@ -2,6 +2,7 @@
// RUN: -config="{CheckOptions: {\
// RUN: misc-const-correctness.TransformValues: true, \
// RUN: misc-const-correctness.WarnPointersAsValues: false, \
+// RUN: misc-const-correctness.WarnPointersAsPointers: false, \
// RUN: misc-const-correctness.TransformPointersAsValues: false \
// RUN: }}" -- -fno-delayed-template-parsing
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values.cpp
index 654deead4efc8..4cf78aeef5bd4 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values.cpp
@@ -2,6 +2,7 @@
// RUN: -config="{CheckOptions: {\
// RUN: misc-const-correctness.TransformValues: true, \
// RUN: misc-const-correctness.WarnPointersAsValues: false, \
+// RUN: misc-const-correctness.WarnPointersAsPointers: false, \
// RUN: misc-const-correctness.TransformPointersAsValues: false \
// RUN: }}" -- -fno-delayed-template-parsing -fexceptions
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-wrong-config.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-wrong-config.cpp
index 29e92e52ca9c7..12c09225f61d2 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-wrong-config.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-wrong-config.cpp
@@ -1,10 +1,11 @@
// RUN: %check_clang_tidy %s misc-const-correctness %t \
// RUN: -config='{CheckOptions: \
// RUN: {"misc-const-correctness.AnalyzeValues": false,\
-// RUN: "misc-const-correctness.AnalyzeReferences": false}\
-// RUN: }' -- -fno-delayed-template-parsing
+// RUN: "misc-const-correctness.AnalyzeReferences": false,\
+// RUN: "misc-const-correctness.AnalyzePointers": false\
+// RUN: }}' -- -fno-delayed-template-parsing
-// CHECK-MESSAGES: warning: The check 'misc-const-correctness' will not perform any analysis because both 'AnalyzeValues' and 'AnalyzeReferences' are false. [clang-tidy-config]
+// CHECK-MESSAGES: warning: The check 'misc-const-correctness' will not perform any analysis because both 'AnalyzeValues', 'AnalyzeReferences' and 'AnalyzePointers' are false. [clang-tidy-config]
void g() {
int p_local0 = 42;
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