forked from OSchip/llvm-project
[clang-tidy] Fix wrong FixIt in performance-move-const-arg
There are incorrect Fixit and missing warnings:
case :
A trivially-copyable object wrapped by std::move is passed to the function with rvalue reference parameters. Removing std::move will cause compilation errors.
```
void showInt(int&&) {}
void testInt() {
int a = 10;
// expect: warning + nofix
showInt(std::move(a)); // showInt(a) <--- wrong fix
}
struct Tmp {};
void showTmp(Tmp&&) {}
void testTmp() {
Tmp t;
// expect: warning + nofix
showTmp(std::move(t)); // showTmp(t) <--- wrong fix
}
```
Reviewed By: aaron.ballman, Quuxplusone
Differential Revision: https://reviews.llvm.org/D107450
This commit is contained in:
Sockke
parent
9006bf4248
commit
a7f8aea714
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@ -47,17 +47,62 @@ void MoveConstArgCheck::registerMatchers(MatchFinder *Finder) {
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Finder->addMatcher(MoveCallMatcher, this);
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auto ConstTypeParmMatcher =
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qualType(references(isConstQualified())).bind("invocation-parm-type");
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auto RValueTypeParmMatcher =
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qualType(rValueReferenceType()).bind("invocation-parm-type");
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// Matches respective ParmVarDecl for a CallExpr or CXXConstructExpr.
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auto ArgumentWithParamMatcher = forEachArgumentWithParam(
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MoveCallMatcher, parmVarDecl(anyOf(hasType(ConstTypeParmMatcher),
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hasType(RValueTypeParmMatcher)))
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.bind("invocation-parm"));
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// Matches respective types of arguments for a CallExpr or CXXConstructExpr
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// and it works on calls through function pointers as well.
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auto ArgumentWithParamTypeMatcher = forEachArgumentWithParamType(
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MoveCallMatcher, anyOf(ConstTypeParmMatcher, RValueTypeParmMatcher));
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Finder->addMatcher(
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invocation(forEachArgumentWithParam(
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MoveCallMatcher,
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parmVarDecl(hasType(references(isConstQualified())))))
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invocation(anyOf(ArgumentWithParamMatcher, ArgumentWithParamTypeMatcher))
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.bind("receiving-expr"),
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this);
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}
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bool IsRValueReferenceParam(const Expr *Invocation,
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const QualType &InvocationParmType,
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const Expr *Arg) {
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if (Invocation && InvocationParmType->isRValueReferenceType() &&
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Arg->isLValue()) {
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if (!Invocation->getType()->isRecordType())
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return true;
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else {
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if (const auto *ConstructCallExpr =
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dyn_cast<CXXConstructExpr>(Invocation)) {
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if (const auto *ConstructorDecl = ConstructCallExpr->getConstructor()) {
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if (!ConstructorDecl->isCopyOrMoveConstructor() &&
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!ConstructorDecl->isDefaultConstructor())
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return true;
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}
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}
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}
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}
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return false;
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}
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void MoveConstArgCheck::check(const MatchFinder::MatchResult &Result) {
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const auto *CallMove = Result.Nodes.getNodeAs<CallExpr>("call-move");
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const auto *ReceivingExpr = Result.Nodes.getNodeAs<Expr>("receiving-expr");
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const auto *InvocationParm =
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Result.Nodes.getNodeAs<ParmVarDecl>("invocation-parm");
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const auto *InvocationParmType =
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Result.Nodes.getNodeAs<QualType>("invocation-parm-type");
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// Skipping matchers which have been matched.
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if (!ReceivingExpr && AlreadyCheckedMoves.contains(CallMove))
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return;
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if (ReceivingExpr)
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AlreadyCheckedMoves.insert(CallMove);
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const Expr *Arg = CallMove->getArg(0);
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SourceManager &SM = Result.Context->getSourceManager();
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@ -90,20 +135,68 @@ void MoveConstArgCheck::check(const MatchFinder::MatchResult &Result) {
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return;
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bool IsVariable = isa<DeclRefExpr>(Arg);
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// std::move shouldn't be removed when an lvalue wrapped by std::move is
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// passed to the function with an rvalue reference parameter.
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bool IsRVRefParam =
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IsRValueReferenceParam(ReceivingExpr, *InvocationParmType, Arg);
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const auto *Var =
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IsVariable ? dyn_cast<DeclRefExpr>(Arg)->getDecl() : nullptr;
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auto Diag = diag(FileMoveRange.getBegin(),
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"std::move of the %select{|const }0"
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"%select{expression|variable %4}1 "
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"%select{|of the trivially-copyable type %5 }2"
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"has no effect; remove std::move()"
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"%select{| or make the variable non-const}3")
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<< IsConstArg << IsVariable << IsTriviallyCopyable
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<< (IsConstArg && IsVariable && !IsTriviallyCopyable) << Var
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<< Arg->getType();
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replaceCallWithArg(CallMove, Diag, SM, getLangOpts());
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{
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auto Diag = diag(FileMoveRange.getBegin(),
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"std::move of the %select{|const }0"
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"%select{expression|variable %5}1 "
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"%select{|of the trivially-copyable type %6 }2"
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"has no effect%select{; remove std::move()|}3"
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"%select{| or make the variable non-const}4")
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<< IsConstArg << IsVariable << IsTriviallyCopyable
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<< IsRVRefParam
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<< (IsConstArg && IsVariable && !IsTriviallyCopyable) << Var
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<< Arg->getType();
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if (!IsRVRefParam)
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replaceCallWithArg(CallMove, Diag, SM, getLangOpts());
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}
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if (IsRVRefParam) {
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// Generate notes for an invocation with an rvalue reference parameter.
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const auto *ReceivingCallExpr = dyn_cast<CallExpr>(ReceivingExpr);
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const auto *ReceivingConstructExpr =
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dyn_cast<CXXConstructExpr>(ReceivingExpr);
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// Skipping the invocation which is a template instantiation.
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if ((!ReceivingCallExpr || !ReceivingCallExpr->getDirectCallee() ||
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ReceivingCallExpr->getDirectCallee()->isTemplateInstantiation()) &&
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(!ReceivingConstructExpr ||
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!ReceivingConstructExpr->getConstructor() ||
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ReceivingConstructExpr->getConstructor()->isTemplateInstantiation()))
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return;
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const NamedDecl *FunctionName = nullptr;
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FunctionName =
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ReceivingCallExpr
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? ReceivingCallExpr->getDirectCallee()->getUnderlyingDecl()
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: ReceivingConstructExpr->getConstructor()->getUnderlyingDecl();
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QualType NoRefType = (*InvocationParmType)->getPointeeType();
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PrintingPolicy PolicyWithSuppressedTag(getLangOpts());
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PolicyWithSuppressedTag.SuppressTagKeyword = true;
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PolicyWithSuppressedTag.SuppressUnwrittenScope = true;
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std::string ExpectParmTypeName =
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NoRefType.getAsString(PolicyWithSuppressedTag);
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if (!NoRefType->isPointerType()) {
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NoRefType.addConst();
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ExpectParmTypeName =
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NoRefType.getAsString(PolicyWithSuppressedTag) + " &";
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}
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diag(InvocationParm->getLocation(),
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"consider changing the %ordinal0 parameter of %1 from %2 to '%3'",
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DiagnosticIDs::Note)
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<< (InvocationParm->getFunctionScopeIndex() + 1) << FunctionName
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<< *InvocationParmType << ExpectParmTypeName;
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}
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} else if (ReceivingExpr) {
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if ((*InvocationParmType)->isRValueReferenceType())
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return;
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auto Diag = diag(FileMoveRange.getBegin(),
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"passing result of std::move() as a const reference "
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"argument; no move will actually happen");
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@ -10,6 +10,7 @@
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_MOVECONSTANTARGUMENTCHECK_H
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#include "../ClangTidyCheck.h"
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#include "llvm/ADT/DenseSet.h"
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namespace clang {
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namespace tidy {
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@ -36,6 +37,7 @@ public:
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private:
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const bool CheckTriviallyCopyableMove;
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llvm::DenseSet<const CallExpr *> AlreadyCheckedMoves;
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};
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} // namespace performance
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@ -175,6 +175,9 @@ Changes in existing checks
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option to control whether to warn on narrowing integer to floating-point
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conversions.
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- Improved :doc:`performance-move-const-arg` check.
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Removed a wrong FixIt for trivially copyable objects wrapped by ``std::move()`` and passed to an rvalue reference parameter. Removal of ``std::move()`` would break the code.
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Removed checks
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^^^^^^^^^^^^^^
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@ -246,3 +246,97 @@ void lambda2() {
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};
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f(MoveSemantics());
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}
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void showInt(int &&v);
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void showInt(int v1, int &&v2);
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void showPointer(const char *&&s);
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void showPointer2(const char *const &&s);
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void showTriviallyCopyable(TriviallyCopyable &&obj);
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void showTriviallyCopyablePointer(const TriviallyCopyable *&&obj);
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void testFunctions() {
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int a = 10;
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showInt(std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-10]]:20: note: consider changing the 1st parameter of 'showInt' from 'int &&' to 'const int &'
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showInt(int());
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showInt(a, std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:14: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-13]]:28: note: consider changing the 2nd parameter of 'showInt' from 'int &&' to 'const int &'
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const char* s = "";
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showPointer(std::move(s));
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// CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-16]]:32: note: consider changing the 1st parameter of 'showPointer' from 'const char *&&' to 'const char *'
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showPointer2(std::move(s));
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// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-18]]:39: note: consider changing the 1st parameter of 'showPointer2' from 'const char *const &&' to 'const char *const'
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TriviallyCopyable *obj = new TriviallyCopyable();
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showTriviallyCopyable(std::move(*obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:25: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-21]]:48: note: consider changing the 1st parameter of 'showTriviallyCopyable' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
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showTriviallyCopyablePointer(std::move(obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:32: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable *' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-23]]:62: note: consider changing the 1st parameter of 'showTriviallyCopyablePointer' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *'
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}
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template <class T>
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void forwardToShowInt(T && t) {
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showInt(static_cast<T &&>(t));
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}
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void testTemplate() {
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int a = 10;
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forwardToShowInt(std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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}
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struct Tmp {
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Tmp();
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Tmp(int &&a);
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Tmp(int v1, int &&a);
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Tmp(const char *&&s);
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Tmp(TriviallyCopyable&& obj);
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Tmp(const TriviallyCopyable *&&obj);
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void showTmp(TriviallyCopyable&& t);
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static void showTmpStatic(TriviallyCopyable&& t);
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};
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void testMethods() {
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Tmp t;
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int a = 10;
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Tmp t1(std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-13]]:13: note: consider changing the 1st parameter of 'Tmp' from 'int &&' to 'const int &'
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Tmp t2(a, std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-15]]:21: note: consider changing the 2nd parameter of 'Tmp' from 'int &&' to 'const int &'
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const char* s = "";
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Tmp t3(std::move(s));
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-18]]:21: note: consider changing the 1st parameter of 'Tmp' from 'const char *&&' to 'const char *'
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TriviallyCopyable *obj = new TriviallyCopyable();
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Tmp t4(std::move(*obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-21]]:27: note: consider changing the 1st parameter of 'Tmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
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Tmp t5(std::move(obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable *' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-23]]:34: note: consider changing the 1st parameter of 'Tmp' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *'
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t.showTmp(std::move(*obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-25]]:36: note: consider changing the 1st parameter of 'showTmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
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Tmp::showTmpStatic(std::move(*obj));
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// CHECK-MESSAGES: :[[@LINE-1]]:22: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
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// CHECK-MESSAGES: :[[@LINE-27]]:49: note: consider changing the 1st parameter of 'showTmpStatic' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
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}
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void showA(A &&v) {}
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void testA() {
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A a;
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showA(std::move(a));
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}
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void testFuncPointer() {
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int a = 10;
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void (*choice)(int, int &&);
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choice = showInt;
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choice(std::move(a), std::move(a));
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect; remove std::move() [performance-move-const-arg]
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// CHECK-FIXES: choice(a, std::move(a));
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// CHECK-MESSAGES: :[[@LINE-3]]:24: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg]
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}
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