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//===--- InvalidEnumDefaultInitializationCheck.cpp - clang-tidy -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "InvalidEnumDefaultInitializationCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/TypeVisitor.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include <algorithm>
using namespace clang::ast_matchers;
namespace clang::tidy::bugprone {
namespace {
bool isCompleteAndHasNoZeroValue(const EnumDecl *D) {
const EnumDecl *Definition = D->getDefinition();
return Definition && Definition->isComplete() &&
!Definition->enumerators().empty() &&
std::none_of(Definition->enumerator_begin(),
Definition->enumerator_end(),
[](const EnumConstantDecl *Value) {
return Value->getInitVal().isZero();
});
}
AST_MATCHER(EnumDecl, isCompleteAndHasNoZeroValue) {
return isCompleteAndHasNoZeroValue(&Node);
}
// Find an initialization which initializes the value (if it has enum type) to a
// default zero value.
AST_MATCHER(Expr, isEmptyInit) {
if (isa<CXXScalarValueInitExpr, ImplicitValueInitExpr>(&Node))
return true;
if (const auto *Init = dyn_cast<InitListExpr>(&Node)) {
if (Init->getNumInits() == 0)
return true;
}
return false;
}
AST_MATCHER(InitListExpr, hasArrayFiller) { return Node.hasArrayFiller(); }
// Check if any type has a "child" type that is an enum without zero value.
// The "child" type can be an array element type or member type of a record
// type (or a recursive combination of these). In this case, if the "root" type
// is statically initialized, the enum component is initialized to zero.
class FindEnumMember : public TypeVisitor<FindEnumMember, bool> {
public:
const EnumType *FoundEnum = nullptr;
bool VisitType(const Type *T) {
const Type *DesT = T->getUnqualifiedDesugaredType();
if (DesT != T)
return Visit(DesT);
return false;
}
bool VisitArrayType(const ArrayType *T) {
return Visit(T->getElementType().getTypePtr());
}
bool VisitConstantArrayType(const ConstantArrayType *T) {
return Visit(T->getElementType().getTypePtr());
}
bool VisitEnumType(const EnumType *T) {
if (isCompleteAndHasNoZeroValue(T->getDecl())) {
FoundEnum = T;
return true;
}
return false;
}
bool VisitRecordType(const RecordType *T) {
const RecordDecl *RD = T->getDecl();
if (RD->isUnion())
return false;
auto VisitField = [this](const FieldDecl *F) {
return Visit(F->getType().getTypePtr());
};
return llvm::any_of(RD->fields(), VisitField);
}
};
} // namespace
InvalidEnumDefaultInitializationCheck::InvalidEnumDefaultInitializationCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context) {}
void InvalidEnumDefaultInitializationCheck::registerMatchers(
MatchFinder *Finder) {
auto EnumWithoutZeroValue = enumType(
hasDeclaration(enumDecl(isCompleteAndHasNoZeroValue()).bind("enum")));
auto EnumOrArrayOfEnum = qualType(hasUnqualifiedDesugaredType(
anyOf(EnumWithoutZeroValue,
arrayType(hasElementType(qualType(
hasUnqualifiedDesugaredType(EnumWithoutZeroValue)))))));
Finder->addMatcher(
expr(isEmptyInit(), hasType(EnumOrArrayOfEnum)).bind("expr"), this);
// Array initialization can contain an "array filler" for the (syntactically)
// unspecified elements. This expression is not found by AST matchers and can
// have any type (the array's element type). This is an implicitly generated
// initialization, so if the type contains somewhere an enum without zero
// enumerator, the zero initialization applies here. We search this array
// element type for the specific enum type manually when this matcher matches.
Finder->addMatcher(initListExpr(hasArrayFiller()).bind("array_filler_expr"),
this);
}
void InvalidEnumDefaultInitializationCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *InitExpr = Result.Nodes.getNodeAs<Expr>("expr");
const auto *Enum = Result.Nodes.getNodeAs<EnumDecl>("enum");
if (!InitExpr) {
const auto *InitList =
Result.Nodes.getNodeAs<InitListExpr>("array_filler_expr");
// Initialization of omitted array elements with array filler was found.
// Check the type for enum without zero value.
// FIXME: In this way only one enum-typed value is found, not all of these.
FindEnumMember Finder;
if (!Finder.Visit(InitList->getArrayFiller()->getType().getTypePtr()))
return;
InitExpr = InitList;
Enum = Finder.FoundEnum->getDecl();
}
if (!InitExpr || !Enum)
return;
ASTContext &ACtx = Enum->getASTContext();
SourceLocation Loc = InitExpr->getExprLoc();
if (Loc.isInvalid()) {
if (isa<ImplicitValueInitExpr, InitListExpr>(InitExpr)) {
DynTypedNodeList Parents = ACtx.getParents(*InitExpr);
if (Parents.empty())
return;
if (const auto *Ctor = Parents[0].get<CXXConstructorDecl>()) {
// Try to find member initializer with the found expression and get the
// source location from it.
CXXCtorInitializer *const *CtorInit = std::find_if(
Ctor->init_begin(), Ctor->init_end(),
[InitExpr](const CXXCtorInitializer *Init) {
return Init->isMemberInitializer() && Init->getInit() == InitExpr;
});
if (!CtorInit)
return;
Loc = (*CtorInit)->getLParenLoc();
} else if (const auto *InitList = Parents[0].get<InitListExpr>()) {
// The expression may be implicitly generated for an initialization.
// Search for a parent initialization list with valid source location.
while (InitList->getExprLoc().isInvalid()) {
DynTypedNodeList Parents = ACtx.getParents(*InitList);
if (Parents.empty())
return;
InitList = Parents[0].get<InitListExpr>();
if (!InitList)
return;
}
Loc = InitList->getExprLoc();
}
}
// If still not found a source location, omit the warning.
// Ideally all such cases (if they exist) should be handled to make the
// check more precise.
if (Loc.isInvalid())
return;
}
diag(Loc, "enum value of type %0 initialized with invalid value of 0, "
"enum doesn't have a zero-value enumerator")
<< Enum;
diag(Enum->getLocation(), "enum is defined here", DiagnosticIDs::Note);
}
} // namespace clang::tidy::bugprone
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