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//===--- ExceptionEscapeCheck.cpp - clang-tidy-----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "ExceptionEscapeCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringSet.h"
using namespace clang::ast_matchers;
namespace {
typedef llvm::SmallVector<const clang::Type *, 8> TypeVec;
} // namespace
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; });
}
static const TypeVec
throwsException(const Stmt *St, const TypeVec &Caught,
llvm::SmallSet<const FunctionDecl *, 32> &CallStack);
static const TypeVec
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;
}
static const TypeVec
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;
}
static const TypeVec throwsException(const FunctionDecl *Func) {
llvm::SmallSet<const FunctionDecl *, 32> CallStack;
return throwsException(Func, CallStack);
}
namespace ast_matchers {
AST_MATCHER_P(FunctionDecl, throws, internal::Matcher<Type>, InnerMatcher) {
TypeVec ExceptionList = throwsException(&Node);
auto NewEnd = llvm::remove_if(
ExceptionList, [this, Finder, Builder](const Type *Exception) {
return !InnerMatcher.matches(*Exception, Finder, Builder);
});
ExceptionList.erase(NewEnd, ExceptionList.end());
return ExceptionList.size();
}
AST_MATCHER_P(Type, isIgnored, llvm::StringSet<>, IgnoredExceptions) {
if (const auto *TD = Node.getAsTagDecl()) {
if (TD->getDeclName().isIdentifier())
return IgnoredExceptions.count(TD->getName()) > 0;
}
return false;
}
AST_MATCHER_P(FunctionDecl, isEnabled, llvm::StringSet<>,
FunctionsThatShouldNotThrow) {
return FunctionsThatShouldNotThrow.count(Node.getNameAsString()) > 0;
}
} // namespace ast_matchers
namespace tidy {
namespace bugprone {
ExceptionEscapeCheck::ExceptionEscapeCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context), RawFunctionsThatShouldNotThrow(Options.get(
"FunctionsThatShouldNotThrow", "")),
RawIgnoredExceptions(Options.get("IgnoredExceptions", "")) {
llvm::SmallVector<StringRef, 8> FunctionsThatShouldNotThrowVec,
IgnoredExceptionsVec;
StringRef(RawFunctionsThatShouldNotThrow)
.split(FunctionsThatShouldNotThrowVec, ",", -1, false);
FunctionsThatShouldNotThrow.insert(FunctionsThatShouldNotThrowVec.begin(),
FunctionsThatShouldNotThrowVec.end());
StringRef(RawIgnoredExceptions).split(IgnoredExceptionsVec, ",", -1, false);
IgnoredExceptions.insert(IgnoredExceptionsVec.begin(),
IgnoredExceptionsVec.end());
}
void ExceptionEscapeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "FunctionsThatShouldNotThrow",
RawFunctionsThatShouldNotThrow);
Options.store(Opts, "IgnoredExceptions", RawIgnoredExceptions);
}
void ExceptionEscapeCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
functionDecl(allOf(anyOf(isNoThrow(), cxxDestructorDecl(),
cxxConstructorDecl(isMoveConstructor()),
cxxMethodDecl(isMoveAssignmentOperator()),
hasName("main"), hasName("swap"),
isEnabled(FunctionsThatShouldNotThrow)),
throws(unless(isIgnored(IgnoredExceptions)))))
.bind("thrower"),
this);
}
void ExceptionEscapeCheck::check(const MatchFinder::MatchResult &Result) {
const FunctionDecl *MatchedDecl =
Result.Nodes.getNodeAs<FunctionDecl>("thrower");
if (!MatchedDecl)
return;
// FIXME: We should provide more information about the exact location where
// the exception is thrown, maybe the full path the exception escapes
diag(MatchedDecl->getLocation(), "an exception may be thrown in function %0 "
"which should not throw exceptions") << MatchedDecl;
}
} // namespace bugprone
} // namespace tidy
} // namespace clang
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