Sockke updated this revision to Diff 396385.
Sockke added a comment.
Sorry for the late reply. I made improvements to the patch in response to the
questions you raised. @aaron.ballman
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D107450/new/
https://reviews.llvm.org/D107450
Files:
clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/test/clang-tidy/checkers/performance-move-const-arg.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/performance-move-const-arg.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/performance-move-const-arg.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/performance-move-const-arg.cpp
@@ -246,3 +246,97 @@
};
f(MoveSemantics());
}
+
+void showInt(int &&v);
+void showInt(int v1, int &&v2);
+void showPointer(const char *&&s);
+void showPointer2(const char *const &&s);
+void showTriviallyCopyable(TriviallyCopyable &&obj);
+void showTriviallyCopyablePointer(const TriviallyCopyable *&&obj);
+void testFunctions() {
+ int a = 10;
+ showInt(std::move(a));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-10]]:20: note: consider changing the 1st parameter of 'showInt' from 'int &&' to 'const int &'
+ showInt(int());
+ showInt(a, std::move(a));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-13]]:28: note: consider changing the 2nd parameter of 'showInt' from 'int &&' to 'const int &'
+ const char* s = "";
+ showPointer(std::move(s));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-16]]:32: note: consider changing the 1st parameter of 'showPointer' from 'const char *&&' to 'const char *'
+ showPointer2(std::move(s));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-18]]:39: note: consider changing the 1st parameter of 'showPointer2' from 'const char *const &&' to 'const char *const'
+ TriviallyCopyable *obj = new TriviallyCopyable();
+ showTriviallyCopyable(std::move(*obj));
+ // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
+ // CHECK-MESSAGES: :[[@LINE-21]]:48: note: consider changing the 1st parameter of 'showTriviallyCopyable' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
+ showTriviallyCopyablePointer(std::move(obj));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-23]]:62: note: consider changing the 1st parameter of 'showTriviallyCopyablePointer' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *'
+}
+template <class T>
+void forwardToShowInt(T && t) {
+ showInt(static_cast<T &&>(t));
+}
+void testTemplate() {
+ int a = 10;
+ forwardToShowInt(std::move(a));
+ // 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]
+}
+
+struct Tmp {
+ Tmp();
+ Tmp(int &&a);
+ Tmp(int v1, int &&a);
+ Tmp(const char *&&s);
+ Tmp(TriviallyCopyable&& obj);
+ Tmp(const TriviallyCopyable *&&obj);
+ void showTmp(TriviallyCopyable&& t);
+ static void showTmpStatic(TriviallyCopyable&& t);
+};
+void testMethods() {
+ Tmp t;
+ int a = 10;
+ Tmp t1(std::move(a));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-13]]:13: note: consider changing the 1st parameter of 'Tmp' from 'int &&' to 'const int &'
+ Tmp t2(a, std::move(a));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-15]]:21: note: consider changing the 2nd parameter of 'Tmp' from 'int &&' to 'const int &'
+ const char* s = "";
+ Tmp t3(std::move(s));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-18]]:21: note: consider changing the 1st parameter of 'Tmp' from 'const char *&&' to 'const char *'
+ TriviallyCopyable *obj = new TriviallyCopyable();
+ Tmp t4(std::move(*obj));
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
+ // CHECK-MESSAGES: :[[@LINE-21]]:27: note: consider changing the 1st parameter of 'Tmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
+ Tmp t5(std::move(obj));
+ // 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]
+ // CHECK-MESSAGES: :[[@LINE-23]]:34: note: consider changing the 1st parameter of 'Tmp' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *'
+ t.showTmp(std::move(*obj));
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
+ // CHECK-MESSAGES: :[[@LINE-25]]:36: note: consider changing the 1st parameter of 'showTmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
+ Tmp::showTmpStatic(std::move(*obj));
+ // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg]
+ // CHECK-MESSAGES: :[[@LINE-27]]:49: note: consider changing the 1st parameter of 'showTmpStatic' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &'
+}
+
+void showA(A &&v) {}
+void testA() {
+ A a;
+ showA(std::move(a));
+}
+
+void testFuncPointer() {
+ int a = 10;
+ void (*choice)(int, int &&);
+ choice = showInt;
+ choice(std::move(a), std::move(a));
+ // 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]
+ // CHECK-FIXES: choice(a, std::move(a));
+ // 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]
+}
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -113,6 +113,10 @@
Changes in existing checks
^^^^^^^^^^^^^^^^^^^^^^^^^^
+- Improved :doc:`performance-move-const-arg` check.
+
+ 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.
+
Removed checks
^^^^^^^^^^^^^^
Index: clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.h
===================================================================
--- clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.h
+++ clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.h
@@ -10,6 +10,7 @@
#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_MOVECONSTANTARGUMENTCHECK_H
#include "../ClangTidyCheck.h"
+#include "llvm/ADT/DenseSet.h"
namespace clang {
namespace tidy {
@@ -36,6 +37,7 @@
private:
const bool CheckTriviallyCopyableMove;
+ llvm::DenseSet<const CallExpr *> AlreadyCheckedMoves;
};
} // namespace performance
Index: clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
+++ clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
@@ -47,10 +47,19 @@
Finder->addMatcher(MoveCallMatcher, this);
+ auto ConstTypeParmMatcher =
+ qualType(references(isConstQualified())).bind("invocation-parm-type");
+ auto RValueTypeParmMatcher =
+ qualType(rValueReferenceType()).bind("invocation-parm-type");
+ auto ArgumentWithParamMatcher = forEachArgumentWithParam(
+ MoveCallMatcher, parmVarDecl(anyOf(hasType(ConstTypeParmMatcher),
+ hasType(RValueTypeParmMatcher)))
+ .bind("invocation-parm"));
+ auto ArgumentWithParamTypeMatcher = forEachArgumentWithParamType(
+ MoveCallMatcher, anyOf(ConstTypeParmMatcher, RValueTypeParmMatcher));
+
Finder->addMatcher(
- invocation(forEachArgumentWithParam(
- MoveCallMatcher,
- parmVarDecl(hasType(references(isConstQualified())))))
+ invocation(anyOf(ArgumentWithParamMatcher, ArgumentWithParamTypeMatcher))
.bind("receiving-expr"),
this);
}
@@ -58,6 +67,17 @@
void MoveConstArgCheck::check(const MatchFinder::MatchResult &Result) {
const auto *CallMove = Result.Nodes.getNodeAs<CallExpr>("call-move");
const auto *ReceivingExpr = Result.Nodes.getNodeAs<Expr>("receiving-expr");
+ const auto *InvocationParm =
+ Result.Nodes.getNodeAs<ParmVarDecl>("invocation-parm");
+ const auto *InvocationParmType =
+ Result.Nodes.getNodeAs<QualType>("invocation-parm-type");
+
+ if (!ReceivingExpr && AlreadyCheckedMoves.contains(CallMove))
+ return;
+
+ if (ReceivingExpr)
+ AlreadyCheckedMoves.insert(CallMove);
+
const Expr *Arg = CallMove->getArg(0);
SourceManager &SM = Result.Context->getSourceManager();
@@ -90,20 +110,78 @@
return;
bool IsVariable = isa<DeclRefExpr>(Arg);
+ bool IsRValueReferenceArg = false;
const auto *Var =
IsVariable ? dyn_cast<DeclRefExpr>(Arg)->getDecl() : nullptr;
- auto Diag = diag(FileMoveRange.getBegin(),
- "std::move of the %select{|const }0"
- "%select{expression|variable %4}1 "
- "%select{|of the trivially-copyable type %5 }2"
- "has no effect; remove std::move()"
- "%select{| or make the variable non-const}3")
- << IsConstArg << IsVariable << IsTriviallyCopyable
- << (IsConstArg && IsVariable && !IsTriviallyCopyable) << Var
- << Arg->getType();
- replaceCallWithArg(CallMove, Diag, SM, getLangOpts());
+ if (ReceivingExpr && (*InvocationParmType)->isRValueReferenceType() &&
+ Arg->isLValue()) {
+ if (ReceivingExpr->getType()->isRecordType()) {
+ const auto *ConstructCallExpr =
+ dyn_cast<CXXConstructExpr>(ReceivingExpr);
+ if (!ConstructCallExpr)
+ return;
+ const auto *ConstructorDecl = ConstructCallExpr->getConstructor();
+ if (!ConstructorDecl)
+ return;
+ if (!ConstructorDecl->isCopyOrMoveConstructor() &&
+ !ConstructorDecl->isDefaultConstructor())
+ IsRValueReferenceArg = true;
+ } else
+ IsRValueReferenceArg = true;
+ }
+
+ {
+ auto Diag = diag(FileMoveRange.getBegin(),
+ "std::move of the %select{|const }0"
+ "%select{expression|variable %5}1 "
+ "%select{|of the trivially-copyable type %6 }2"
+ "has no effect%select{; remove std::move()|}3"
+ "%select{| or make the variable non-const}4")
+ << IsConstArg << IsVariable << IsTriviallyCopyable
+ << IsRValueReferenceArg
+ << (IsConstArg && IsVariable && !IsTriviallyCopyable) << Var
+ << Arg->getType();
+ if (!IsRValueReferenceArg)
+ replaceCallWithArg(CallMove, Diag, SM, getLangOpts());
+ }
+ if (IsRValueReferenceArg && InvocationParm) {
+ const auto *ReceivingCallExpr = dyn_cast<CallExpr>(ReceivingExpr);
+ const auto *ReceivingConstructExpr =
+ dyn_cast<CXXConstructExpr>(ReceivingExpr);
+ if ((!ReceivingCallExpr ||
+ ReceivingCallExpr->getDirectCallee()->isTemplateInstantiation()) &&
+ (!ReceivingConstructExpr ||
+ ReceivingConstructExpr->getConstructor()->isTemplateInstantiation()))
+ return;
+ const NamedDecl *FunctionName = nullptr;
+ if (ReceivingCallExpr)
+ FunctionName =
+ ReceivingCallExpr->getDirectCallee()->getUnderlyingDecl();
+ else
+ FunctionName =
+ ReceivingConstructExpr->getConstructor()->getUnderlyingDecl();
+ QualType NoRefType = (*InvocationParmType)->getPointeeType();
+ PrintingPolicy PolicyWithSupressedTag(getLangOpts());
+ PolicyWithSupressedTag.SuppressTagKeyword = true;
+ PolicyWithSupressedTag.SuppressUnwrittenScope = true;
+ std::string ExpectParmTypeName =
+ NoRefType.getAsString(PolicyWithSupressedTag);
+ if (!NoRefType->isPointerType()) {
+ NoRefType.addConst();
+ ExpectParmTypeName =
+ NoRefType.getAsString(PolicyWithSupressedTag) + " &";
+ }
+ diag(InvocationParm->getLocation(),
+ "consider changing the %ordinal0 parameter of %1 from %2 to '%3'",
+ DiagnosticIDs::Note)
+ << (InvocationParm->getFunctionScopeIndex() + 1) << FunctionName
+ << *InvocationParmType << ExpectParmTypeName;
+ }
} else if (ReceivingExpr) {
+ if ((*InvocationParmType)->isRValueReferenceType())
+ return;
+
auto Diag = diag(FileMoveRange.getBegin(),
"passing result of std::move() as a const reference "
"argument; no move will actually happen");
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