[clang-tidy][misc-const-correctness] fix fp when using const array type.

Fixed: #132931
const array is immutable in C/C++ language design, we don't need to
check constness for it.

Author: HerrCai0907

clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp

@@ -89,6 +89,8 @@ void ConstCorrectnessCheck::registerMatchers(MatchFinder *Finder) {
   const auto ConstReference = hasType(references(isConstQualified()));
   const auto RValueReference = hasType(
       referenceType(anyOf(rValueReferenceType(), unless(isSpelledAsLValue()))));
+  const auto ConstArrayType =
+      hasType(arrayType(hasElementType(isConstQualified())));
 
   const auto TemplateType = anyOf(
       hasType(hasCanonicalType(templateTypeParmType())),
@@ -115,7 +117,7 @@ void ConstCorrectnessCheck::registerMatchers(MatchFinder *Finder) {
   // Example: `int i = 10` would match `int i`.
   const auto LocalValDecl = varDecl(
       isLocal(), hasInitializer(anything()),
-      unless(anyOf(ConstType, ConstReference, TemplateType,
+      unless(anyOf(ConstType, ConstReference, ConstArrayType, TemplateType,
                    hasInitializer(isInstantiationDependent()), AutoTemplateType,
                    RValueReference, FunctionPointerRef,
                    hasType(cxxRecordDecl(isLambda())), isImplicit(),
@@ -161,6 +163,7 @@ void ConstCorrectnessCheck::check(const MatchFinder::MatchResult &Result) {
 
   VariableCategory VC = VariableCategory::Value;
   const QualType VT = Variable->getType();
+  VT->dump();
   if (VT->isReferenceType()) {
     VC = VariableCategory::Reference;
   } else if (VT->isPointerType()) {
@@ -169,6 +172,7 @@ void ConstCorrectnessCheck::check(const MatchFinder::MatchResult &Result) {
     if (ArrayT->getElementType()->isPointerType())
       VC = VariableCategory::Pointer;
   }
+  llvm::errs() << (int)VC << "\n";
 
   auto CheckValue = [&]() {
     // The scope is only registered if the analysis shall be run.

clang-tools-extra/docs/ReleaseNotes.rst

@@ -146,7 +146,8 @@ Changes in existing checks
   `AllowedTypes`, that excludes specified types from const-correctness
   checking and fixing false positives when modifying variant by ``operator[]``
   with template in parameters and supporting to check pointee mutation by
-  `AnalyzePointers` option.
+  `AnalyzePointers` option and fixing false positives when using const array
+  type.
 
 - Improved :doc:`misc-redundant-expression
   <clang-tidy/checks/misc/redundant-expression>` check by providing additional

clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-values.cpp

@@ -1007,3 +1007,11 @@ template <typename T> void f() {
   x[T{}] = 3;
 }
 } // namespace gh127776_false_positive
+
+namespace gh132931_false_positive {
+using T = const int;
+void valid(int i) {
+  const int arr0[] = {1, 2, 3};
+  T arr1[] = {1, 2, 3};
+}
+} // namespace gh132931_false_positive