Consolidate the checking to SemaInit.cpp
Ass warning for redundant move on return
http://reviews.llvm.org/D7633
Files:
include/clang/Basic/DiagnosticGroups.td
include/clang/Basic/DiagnosticSemaKinds.td
lib/Sema/SemaInit.cpp
test/SemaCXX/warn-pessmizing-move.cpp
test/SemaCXX/warn-redundant-move.cpp
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Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -286,6 +286,7 @@
def ExplicitInitializeCall : DiagGroup<"explicit-initialize-call">;
def Packed : DiagGroup<"packed">;
def Padded : DiagGroup<"padded">;
+def PessimizingMove : DiagGroup<"pessimizing-move">;
def PointerArith : DiagGroup<"pointer-arith">;
def PoundWarning : DiagGroup<"#warnings">;
def PoundPragmaMessage : DiagGroup<"#pragma-messages">,
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -4764,6 +4764,17 @@
"explicitly moving variable of type %0 to itself">,
InGroup<SelfMove>, DefaultIgnore;
+def warn_pessimizing_move_on_return : Warning<
+ "moving a local object in a return statement prevents copy elision">,
+ InGroup<PessimizingMove>, DefaultIgnore;
+def warn_redundant_move_on_return : Warning<
+ "redundant move in return statement">,
+ InGroup<DiagGroup<"redundant-move">>, DefaultIgnore;
+def warn_pessimizing_move_on_initialization : Warning<
+ "moving a temporary object prevents copy elision">,
+ InGroup<PessimizingMove>, DefaultIgnore;
+def note_remove_move : Note<"remove std::move call here">;
+
def warn_string_plus_int : Warning<
"adding %0 to a string does not append to the string">,
InGroup<StringPlusInt>;
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -7337,6 +7337,64 @@
return !Seq.Failed();
}
+static void CheckMoveOnConstruction(Sema &SemaRef, const Expr *InitExpr,
+ bool IsReturnStmt) {
+ if (!InitExpr)
+ return;
+
+ QualType DestType = InitExpr->getType();
+ if (DestType->isReferenceType() || !DestType->isRecordType())
+ return;
+
+ if (IsReturnStmt) {
+ const CXXConstructExpr *CCE =
+ dyn_cast<CXXConstructExpr>(InitExpr->IgnoreParens());
+ if (!CCE || !CCE->getConstructor()->isCopyOrMoveConstructor())
+ return;
+
+ InitExpr = CCE->getArg(0)->IgnoreImpCasts();
+ }
+
+ const CallExpr *CE = dyn_cast<CallExpr>(InitExpr->IgnoreParens());
+ if (!CE || CE->getNumArgs() != 1)
+ return;
+
+ const FunctionDecl *MoveFunction = CE->getDirectCallee();
+ if (!MoveFunction || !MoveFunction->isInStdNamespace() ||
+ !MoveFunction->getIdentifier() ||
+ !MoveFunction->getIdentifier()->isStr("move"))
+ return;
+
+ const Expr *Arg = CE->getArg(0)->IgnoreImplicit();
+
+ unsigned DiagID = 0;
+ if (IsReturnStmt) {
+ DiagID = diag::warn_pessimizing_move_on_return;
+ const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg->IgnoreParenImpCasts());
+ if (!DRE)
+ return;
+
+ const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl());
+ if (!VD || !VD->hasLocalStorage())
+ return;
+
+ if (!SemaRef.Context.hasSameUnqualifiedType(DestType, VD->getType()))
+ DiagID = diag::warn_redundant_move_on_return;
+ } else {
+ DiagID = diag::warn_pessimizing_move_on_initialization;
+ const Expr *ArgStripped = Arg->IgnoreImplicit()->IgnoreParens();
+ if (!ArgStripped->isRValue() || !ArgStripped->getType()->isRecordType())
+ return;
+ }
+
+ SemaRef.Diag(CE->getLocStart(), DiagID);
+ SemaRef.Diag(CE->getLocStart(), diag::note_remove_move)
+ << FixItHint::CreateRemoval(SourceRange(
+ CE->getLocStart(), Arg->getLocStart().getLocWithOffset(-1)))
+ << FixItHint::CreateRemoval(
+ SourceRange(CE->getRParenLoc(), CE->getRParenLoc()));
+}
+
ExprResult
Sema::PerformCopyInitialization(const InitializedEntity &Entity,
SourceLocation EqualLoc,
@@ -7359,5 +7417,10 @@
ExprResult Result = Seq.Perform(*this, Entity, Kind, InitE);
+ if (const Expr *E = Result.get()) {
+ CheckMoveOnConstruction(*this, E,
+ Entity.getKind() == InitializedEntity::EK_Result);
+ }
+
return Result;
}
Index: test/SemaCXX/warn-pessmizing-move.cpp
===================================================================
--- test/SemaCXX/warn-pessmizing-move.cpp
+++ test/SemaCXX/warn-pessmizing-move.cpp
@@ -0,0 +1,161 @@
+// RUN: %clang_cc1 -fsyntax-only -Wpessimizing-move -std=c++11 -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wpessimizing-move -std=c++11 -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+// definitions for std::move
+namespace std {
+inline namespace foo {
+template <class T> struct remove_reference { typedef T type; };
+template <class T> struct remove_reference<T&> { typedef T type; };
+template <class T> struct remove_reference<T&&> { typedef T type; };
+
+template <class T> typename remove_reference<T>::type &&move(T &&t);
+}
+}
+
+struct A {};
+struct B {
+ B() {}
+ B(A) {}
+};
+
+A test1(A a1) {
+ A a2;
+ return a1;
+ return a2;
+ return std::move(a1);
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+ return std::move(a2);
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+}
+
+B test2(A a1, B b1) {
+ // Object is different than return type so don't warn.
+ A a2;
+ return a1;
+ return a2;
+ return std::move(a1);
+ return std::move(a2);
+
+ B b2;
+ return b1;
+ return b2;
+ return std::move(b1);
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+ return std::move(b2);
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+}
+
+A global_a;
+A test3() {
+ // Don't warn when object is not local.
+ return global_a;
+ return std::move(global_a);
+ static A static_a;
+ return static_a;
+ return std::move(static_a);
+
+}
+
+A test4() {
+ return A();
+ return test3();
+
+ return std::move(A());
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:23-[[@LINE-4]]:24}:""
+ return std::move(test3());
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:27-[[@LINE-4]]:28}:""
+}
+
+void test5(A) {
+ test5(A());
+ test5(test4());
+
+ test5(std::move(A()));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:9-[[@LINE-3]]:19}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+ test5(std::move(test4()));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:9-[[@LINE-3]]:19}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:26-[[@LINE-4]]:27}:""
+}
+
+void test6() {
+ A a1 = A();
+ A a2 = test3();
+
+ A a3 = std::move(A());
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:23-[[@LINE-4]]:24}:""
+ A a4 = std::move(test3());
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:27-[[@LINE-4]]:28}:""
+}
+
+A test7() {
+ A a1 = std::move(A());
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:23-[[@LINE-4]]:24}:""
+ A a2 = std::move((A()));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:25-[[@LINE-4]]:26}:""
+ A a3 = (std::move(A()));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:11-[[@LINE-3]]:21}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:24-[[@LINE-4]]:25}:""
+ A a4 = (std::move((A())));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:11-[[@LINE-3]]:21}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:26-[[@LINE-4]]:27}:""
+
+ return std::move(a1);
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+ return std::move((a1));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:24-[[@LINE-4]]:25}:""
+ return (std::move(a1));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:11-[[@LINE-3]]:21}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:23-[[@LINE-4]]:24}:""
+ return (std::move((a1)));
+ // expected-warning@-1{{prevents copy elision}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:11-[[@LINE-3]]:21}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:25-[[@LINE-4]]:26}:""
+}
Index: test/SemaCXX/warn-redundant-move.cpp
===================================================================
--- test/SemaCXX/warn-redundant-move.cpp
+++ test/SemaCXX/warn-redundant-move.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -fsyntax-only -Wredundant-move -std=c++11 -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wredundant-move -std=c++11 -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+// definitions for std::move
+namespace std {
+inline namespace foo {
+template <class T> struct remove_reference { typedef T type; };
+template <class T> struct remove_reference<T&> { typedef T type; };
+template <class T> struct remove_reference<T&&> { typedef T type; };
+
+template <class T> typename remove_reference<T>::type &&move(T &&t);
+}
+}
+
+struct A {};
+struct B : public A {};
+
+A test1(B b1) {
+ B b2;
+ return b1;
+ return b2;
+ return std::move(b1);
+ // expected-warning@-1{{redundant move}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+ return std::move(b2);
+ // expected-warning@-1{{redundant move}}
+ // expected-note@-2{{remove std::move call}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:20}:""
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:22-[[@LINE-4]]:23}:""
+}
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