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clang-tools-extra
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[clang-tidy] UnnecessaryCopyInitialization - Extend to trigger on non-const "this" object argument if it is not modified. 

Summary:

Also trigger the check in the following case:

void foo() {
  ExpensiveToCopy Obj;
  const auto UnnecessaryCopy = Obj.constReference();
  Obj.onlyUsedAsConst();
}

i.e. when the object the method is called on is not const but is never
modified.

Reviewers: alexfh, fowles

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D20010

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@271239 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Felix Berger 2016-05-31 00:25:57 +00:00
Родитель d3a1e8c51d
Коммит f506f18103
3 изменённых файлов: 74 добавлений и 44 удалений
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26
clang-tidy/performance/UnnecessaryCopyInitialization.cpp
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@ -38,14 +38,15 @@ void UnnecessaryCopyInitialization::registerMatchers(MatchFinder *Finder) {
unless(allOf(pointerType(), unless(pointerType(pointee(
qualType(isConstQualified())))))));
// Match method call expressions where the this argument is a const
// type or const reference. This returned const reference is highly likely to
// outlive the local const reference of the variable being declared.
// The assumption is that the const reference being returned either points
// to a global static variable or to a member of the called object.
auto ConstRefReturningMethodCallOfConstParam = cxxMemberCallExpr(
// Match method call expressions where the `this` argument is only used as
// const, this will be checked in `check()` part. This returned const
// reference is highly likely to outlive the local const reference of the
// variable being declared. The assumption is that the const reference being
// returned either points to a global static variable or to a member of the
// called object.
auto ConstRefReturningMethodCall = cxxMemberCallExpr(
callee(cxxMethodDecl(returns(ConstReference))),
on(declRefExpr(to(varDecl(hasType(qualType(ConstOrConstReference)))))));
on(declRefExpr(to(varDecl().bind("objectArg")))));
auto ConstRefReturningFunctionCall =
callExpr(callee(functionDecl(returns(ConstReference))),
unless(callee(cxxMethodDecl())));
@ -68,7 +69,7 @@ void UnnecessaryCopyInitialization::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
localVarCopiedFrom(anyOf(ConstRefReturningFunctionCall,
ConstRefReturningMethodCallOfConstParam)),
ConstRefReturningMethodCall)),
this);
Finder->addMatcher(localVarCopiedFrom(declRefExpr(
@ -80,6 +81,7 @@ void UnnecessaryCopyInitialization::check(
const MatchFinder::MatchResult &Result) {
const auto *NewVar = Result.Nodes.getNodeAs<VarDecl>("newVarDecl");
const auto *OldVar = Result.Nodes.getNodeAs<VarDecl>("oldVarDecl");
const auto *ObjectArg = Result.Nodes.getNodeAs<VarDecl>("objectArg");
const auto *BlockStmt = Result.Nodes.getNodeAs<Stmt>("blockStmt");
const auto *CtorCall = Result.Nodes.getNodeAs<CXXConstructExpr>("ctorCall");
// Do not propose fixes if the DeclStmt has multiple VarDecls or in macros
@ -96,7 +98,8 @@ void UnnecessaryCopyInitialization::check(
return;
if (OldVar == nullptr) {
handleCopyFromMethodReturn(*NewVar, *BlockStmt, IssueFix, *Result.Context);
handleCopyFromMethodReturn(*NewVar, *BlockStmt, IssueFix, ObjectArg,
*Result.Context);
} else {
handleCopyFromLocalVar(*NewVar, *OldVar, *BlockStmt, IssueFix,
*Result.Context);
@ -105,10 +108,13 @@ void UnnecessaryCopyInitialization::check(
void UnnecessaryCopyInitialization::handleCopyFromMethodReturn(
const VarDecl &Var, const Stmt &BlockStmt, bool IssueFix,
ASTContext &Context) {
const VarDecl *ObjectArg, ASTContext &Context) {
bool IsConstQualified = Var.getType().isConstQualified();
if (!IsConstQualified && !isOnlyUsedAsConst(Var, BlockStmt, Context))
return;
if (ObjectArg != nullptr &&
!isOnlyUsedAsConst(*ObjectArg, BlockStmt, Context))
return;
auto Diagnostic =
diag(Var.getLocation(),

3
clang-tidy/performance/UnnecessaryCopyInitialization.h
Просмотреть файл

@ -33,7 +33,8 @@ public:
private:
void handleCopyFromMethodReturn(const VarDecl &Var, const Stmt &BlockStmt,
bool IssueFix, ASTContext &Context);
bool IssueFix, const VarDecl *ObjectArg,
ASTContext &Context);
void handleCopyFromLocalVar(const VarDecl &NewVar, const VarDecl &OldVar,
const Stmt &BlockStmt, bool IssueFix,
ASTContext &Context);

89
test/clang-tidy/performance-unnecessary-copy-initialization.cpp
Просмотреть файл

@ -36,65 +36,65 @@ void PositiveFunctionCall() {
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned' is copy-constructed from a const reference; consider making it a const reference [performance-unnecessary-copy-initialization]
// CHECK-FIXES: const auto& AutoAssigned = ExpensiveTypeReference();
const auto AutoCopyConstructed(ExpensiveTypeReference());
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoCopyConstructed'
// CHECK-FIXES: const auto& AutoCopyConstructed(ExpensiveTypeReference());
const ExpensiveToCopyType VarAssigned = ExpensiveTypeReference();
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarAssigned'
// CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = ExpensiveTypeReference();
const ExpensiveToCopyType VarCopyConstructed(ExpensiveTypeReference());
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarCopyConstructed'
// CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(ExpensiveTypeReference());
}
void PositiveMethodCallConstReferenceParam(const ExpensiveToCopyType &Obj) {
const auto AutoAssigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj.reference();
const auto AutoCopyConstructed(Obj.reference());
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoCopyConstructed'
// CHECK-FIXES: const auto& AutoCopyConstructed(Obj.reference());
const ExpensiveToCopyType VarAssigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarAssigned'
// CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = Obj.reference();
const ExpensiveToCopyType VarCopyConstructed(Obj.reference());
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarCopyConstructed'
// CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(Obj.reference());
}
void PositiveMethodCallConstParam(const ExpensiveToCopyType Obj) {
const auto AutoAssigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj.reference();
const auto AutoCopyConstructed(Obj.reference());
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoCopyConstructed'
// CHECK-FIXES: const auto& AutoCopyConstructed(Obj.reference());
const ExpensiveToCopyType VarAssigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarAssigned'
// CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = Obj.reference();
const ExpensiveToCopyType VarCopyConstructed(Obj.reference());
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarCopyConstructed'
// CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(Obj.reference());
}
void PositiveMethodCallConstPointerParam(const ExpensiveToCopyType *const Obj) {
const auto AutoAssigned = Obj->reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj->reference();
const auto AutoCopyConstructed(Obj->reference());
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoCopyConstructed'
// CHECK-FIXES: const auto& AutoCopyConstructed(Obj->reference());
const ExpensiveToCopyType VarAssigned = Obj->reference();
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarAssigned'
// CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = Obj->reference();
const ExpensiveToCopyType VarCopyConstructed(Obj->reference());
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarCopyConstructed'
// CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(Obj->reference());
}
void PositiveLocalConstValue() {
const ExpensiveToCopyType Obj;
const auto UnnecessaryCopy = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'UnnecessaryCopy'
// CHECK-FIXES: const auto& UnnecessaryCopy = Obj.reference();
}
@ -102,7 +102,7 @@ void PositiveLocalConstRef() {
const ExpensiveToCopyType Obj;
const ExpensiveToCopyType &ConstReference = Obj.reference();
const auto UnnecessaryCopy = ConstReference.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'UnnecessaryCopy'
// CHECK-FIXES: const auto& UnnecessaryCopy = ConstReference.reference();
}
@ -110,7 +110,7 @@ void PositiveLocalConstPointer() {
const ExpensiveToCopyType Obj;
const ExpensiveToCopyType *const ConstPointer = &Obj;
const auto UnnecessaryCopy = ConstPointer->reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'UnnecessaryCopy'
// CHECK-FIXES: const auto& UnnecessaryCopy = ConstPointer->reference();
}
@ -130,20 +130,20 @@ void PositiveFunctionCallExpensiveTypeNonConstVariable() {
// CHECK-MESSAGES: [[@LINE-1]]:8: warning: the variable 'AutoAssigned' is copy-constructed from a const reference but is only used as const reference; consider making it a const reference [performance-unnecessary-copy-initialization]
// CHECK-FIXES: const auto& AutoAssigned = ExpensiveTypeReference();
auto AutoCopyConstructed(ExpensiveTypeReference());
// CHECK-MESSAGES: [[@LINE-1]]:8: warning: the variable
// CHECK-MESSAGES: [[@LINE-1]]:8: warning: the variable 'AutoCopyConstructed'
// CHECK-FIXES: const auto& AutoCopyConstructed(ExpensiveTypeReference());
ExpensiveToCopyType VarAssigned = ExpensiveTypeReference();
// CHECK-MESSAGES: [[@LINE-1]]:23: warning: the variable
// CHECK-MESSAGES: [[@LINE-1]]:23: warning: the variable 'VarAssigned'
// CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = ExpensiveTypeReference();
ExpensiveToCopyType VarCopyConstructed(ExpensiveTypeReference());
// CHECK-MESSAGES: [[@LINE-1]]:23: warning: the variable
// CHECK-MESSAGES: [[@LINE-1]]:23: warning: the variable 'VarCopyConstructed'
// CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(ExpensiveTypeReference());
}
void positiveNonConstVarInCodeBlock(const ExpensiveToCopyType &Obj) {
{
auto Assigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:10: warning: the variable
// CHECK-MESSAGES: [[@LINE-1]]:10: warning: the variable 'Assigned'
// CHECK-FIXES: const auto& Assigned = Obj.reference();
Assigned.reference();
useAsConstReference(Assigned);
@ -174,33 +174,57 @@ void negativeNonConstVarWithNonConstUse(const ExpensiveToCopyType &Obj) {
}
}
void NegativeMethodCallNonConstRef(ExpensiveToCopyType &Obj) {
void PositiveMethodCallNonConstRefNotModified(ExpensiveToCopyType &Obj) {
const auto AutoAssigned = Obj.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj.reference();
}
void NegativeMethodCallNonConstRefIsModified(ExpensiveToCopyType &Obj) {
const auto AutoAssigned = Obj.reference();
const auto AutoCopyConstructed(Obj.reference());
const ExpensiveToCopyType VarAssigned = Obj.reference();
const ExpensiveToCopyType VarCopyConstructed(Obj.reference());
mutate(&Obj);
}
void NegativeMethodCallNonConst(ExpensiveToCopyType Obj) {
void PositiveMethodCallNonConstNotModified(ExpensiveToCopyType Obj) {
const auto AutoAssigned = Obj.reference();
const auto AutoCopyConstructed(Obj.reference());
const ExpensiveToCopyType VarAssigned = Obj.reference();
const ExpensiveToCopyType VarCopyConstructed(Obj.reference());
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj.reference();
}
void NegativeMethodCallNonConstPointer(ExpensiveToCopyType *const Obj) {
void NegativeMethodCallNonConstValueArgumentIsModified(ExpensiveToCopyType Obj) {
Obj.nonConstMethod();
const auto AutoAssigned = Obj.reference();
}
void PositiveMethodCallNonConstPointerNotModified(ExpensiveToCopyType *const Obj) {
const auto AutoAssigned = Obj->reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = Obj->reference();
Obj->constMethod();
}
void NegativeMethodCallNonConstPointerIsModified(ExpensiveToCopyType *const Obj) {
const auto AutoAssigned = Obj->reference();
const auto AutoCopyConstructed(Obj->reference());
const ExpensiveToCopyType VarAssigned = Obj->reference();
const ExpensiveToCopyType VarCopyConstructed(Obj->reference());
mutate(Obj);
}
void NegativeObjIsNotParam() {
void PositiveLocalVarIsNotModified() {
ExpensiveToCopyType LocalVar;
const auto AutoAssigned = LocalVar.reference();
// CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
// CHECK-FIXES: const auto& AutoAssigned = LocalVar.reference();
}
void NegativeLocalVarIsModified() {
ExpensiveToCopyType Obj;
const auto AutoAssigned = Obj.reference();
const auto AutoCopyConstructed(Obj.reference());
ExpensiveToCopyType VarAssigned = Obj.reference();
ExpensiveToCopyType VarCopyConstructed(Obj.reference());
Obj = AutoAssigned;
}
struct NegativeConstructor {
@ -338,7 +362,6 @@ void NegativeLocalCopyWeirdNonCopy() {
WeirdCopyCtorType neg_weird_1(orig, false);
WeirdCopyCtorType neg_weird_2(orig, true);
}
void WarningOnlyMultiDeclStmt() {
ExpensiveToCopyType orig;
ExpensiveToCopyType copy = orig, copy2;