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//===--- ExceptionAnalyzer.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 "ExceptionAnalyzer.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
namespace clang {
static bool isBaseOf(const Type *DerivedType, const Type *BaseType) {
const auto *DerivedClass = DerivedType->getAsCXXRecordDecl();
const auto *BaseClass = BaseType->getAsCXXRecordDecl();
if (!DerivedClass || !BaseClass)
return false;
return !DerivedClass->forallBases(
[BaseClass](const CXXRecordDecl *Cur) { return Cur != BaseClass; });
}
namespace tidy {
namespace utils {
ExceptionAnalyzer::TypeVec ExceptionAnalyzer::throwsException(
const FunctionDecl *Func,
llvm::SmallSet<const FunctionDecl *, 32> &CallStack) {
if (CallStack.count(Func))
return TypeVec();
if (const Stmt *Body = Func->getBody()) {
CallStack.insert(Func);
const TypeVec Result = throwsException(Body, TypeVec(), CallStack);
CallStack.erase(Func);
return Result;
}
TypeVec Result;
if (const auto *FPT = Func->getType()->getAs<FunctionProtoType>()) {
for (const QualType Ex : FPT->exceptions()) {
Result.push_back(Ex.getTypePtr());
}
}
return Result;
}
ExceptionAnalyzer::TypeVec ExceptionAnalyzer::throwsException(
const Stmt *St, const TypeVec &Caught,
llvm::SmallSet<const FunctionDecl *, 32> &CallStack) {
TypeVec Results;
if (!St)
return Results;
if (const auto *Throw = dyn_cast<CXXThrowExpr>(St)) {
if (const auto *ThrownExpr = Throw->getSubExpr()) {
const auto *ThrownType =
ThrownExpr->getType()->getUnqualifiedDesugaredType();
if (ThrownType->isReferenceType()) {
ThrownType = ThrownType->castAs<ReferenceType>()
->getPointeeType()
->getUnqualifiedDesugaredType();
}
if (const auto *TD = ThrownType->getAsTagDecl()) {
if (TD->getDeclName().isIdentifier() && TD->getName() == "bad_alloc" &&
TD->isInStdNamespace())
return Results;
}
Results.push_back(ThrownExpr->getType()->getUnqualifiedDesugaredType());
} else {
Results.append(Caught.begin(), Caught.end());
}
} else if (const auto *Try = dyn_cast<CXXTryStmt>(St)) {
TypeVec Uncaught = throwsException(Try->getTryBlock(), Caught, CallStack);
for (unsigned i = 0; i < Try->getNumHandlers(); ++i) {
const CXXCatchStmt *Catch = Try->getHandler(i);
if (!Catch->getExceptionDecl()) {
const TypeVec Rethrown =
throwsException(Catch->getHandlerBlock(), Uncaught, CallStack);
Results.append(Rethrown.begin(), Rethrown.end());
Uncaught.clear();
} else {
const auto *CaughtType =
Catch->getCaughtType()->getUnqualifiedDesugaredType();
if (CaughtType->isReferenceType()) {
CaughtType = CaughtType->castAs<ReferenceType>()
->getPointeeType()
->getUnqualifiedDesugaredType();
}
auto NewEnd =
llvm::remove_if(Uncaught, [&CaughtType](const Type *ThrownType) {
return ThrownType == CaughtType ||
isBaseOf(ThrownType, CaughtType);
});
if (NewEnd != Uncaught.end()) {
Uncaught.erase(NewEnd, Uncaught.end());
const TypeVec Rethrown = throwsException(
Catch->getHandlerBlock(), TypeVec(1, CaughtType), CallStack);
Results.append(Rethrown.begin(), Rethrown.end());
}
}
}
Results.append(Uncaught.begin(), Uncaught.end());
} else if (const auto *Call = dyn_cast<CallExpr>(St)) {
if (const FunctionDecl *Func = Call->getDirectCallee()) {
TypeVec Excs = throwsException(Func, CallStack);
Results.append(Excs.begin(), Excs.end());
}
} else {
for (const Stmt *Child : St->children()) {
TypeVec Excs = throwsException(Child, Caught, CallStack);
Results.append(Excs.begin(), Excs.end());
}
}
return Results;
}
bool ExceptionAnalyzer::throwsException(const FunctionDecl *Func) {
// Check if the function has already been analyzed and reuse that result.
if (FunctionCache.count(Func) > 0)
return FunctionCache[Func];
llvm::SmallSet<const FunctionDecl *, 32> CallStack;
TypeVec ExceptionList = throwsException(Func, CallStack);
// Remove all ignored exceptions from the list of exceptions that can be
// thrown.
auto NewEnd = llvm::remove_if(ExceptionList, [this](const Type *Exception) {
return isIgnoredExceptionType(Exception);
});
ExceptionList.erase(NewEnd, ExceptionList.end());
// Cache the result of the analysis.
bool FunctionThrows = ExceptionList.size() > 0;
FunctionCache.insert(std::make_pair(Func, FunctionThrows));
return FunctionThrows;
}
bool ExceptionAnalyzer::isIgnoredExceptionType(const Type *Exception) {
if (const auto *TD = Exception->getAsTagDecl()) {
if (TD->getDeclName().isIdentifier())
return IgnoredExceptions.count(TD->getName()) > 0;
}
return false;
}
} // namespace utils
} // namespace tidy
} // namespace clang
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