Author: davide Date: Fri Jul 17 20:15:19 2015 New Revision: 242600 URL: http://llvm.org/viewvc/llvm-project?rev=242600&view=rev Log: [Sema] Emit correct warning when copy-elision is not possible.
If we're returning a function parameter, copy elision isn't possible, so we now warn for redundant move. PR: 23819 Differential Revision: http://reviews.llvm.org/D11305 Modified: cfe/trunk/lib/Sema/SemaInit.cpp cfe/trunk/test/SemaCXX/warn-pessmizing-move.cpp cfe/trunk/test/SemaCXX/warn-redundant-move.cpp Modified: cfe/trunk/lib/Sema/SemaInit.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=242600&r1=242599&r2=242600&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaInit.cpp (original) +++ cfe/trunk/lib/Sema/SemaInit.cpp Fri Jul 17 20:15:19 2015 @@ -5988,6 +5988,11 @@ static void CheckMoveOnConstruction(Sema if (!VD->getType()->isRecordType()) return; + // If we're returning a function parameter, copy elision + // is not possible. + if (isa<ParmVarDecl>(VD)) + DiagID = diag::warn_redundant_move_on_return; + if (DiagID == 0) { DiagID = S.Context.hasSameUnqualifiedType(DestType, VD->getType()) ? diag::warn_pessimizing_move_on_return Modified: cfe/trunk/test/SemaCXX/warn-pessmizing-move.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-pessmizing-move.cpp?rev=242600&r1=242599&r2=242600&view=diff ============================================================================== --- cfe/trunk/test/SemaCXX/warn-pessmizing-move.cpp (original) +++ cfe/trunk/test/SemaCXX/warn-pessmizing-move.cpp Fri Jul 17 20:15:19 2015 @@ -23,10 +23,6 @@ A test1(A a1) { 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}} @@ -46,10 +42,6 @@ B test2(A a1, B b1) { 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}} @@ -163,9 +155,10 @@ A test7() { #define wrap1(x) x #define wrap2(x) x -// Macro test. Since the std::move call is outside the macro, it is +// Macro test. Since the std::move call is outside the macro, it is // safe to suggest a fix-it. -A test8(A a) { +A test8() { + A a; return std::move(a); // expected-warning@-1{{prevents copy elision}} // expected-note@-2{{remove std::move call}} @@ -184,7 +177,8 @@ A test8(A a) { } #define test9 \ - A test9(A a) { \ + A test9() { \ + A a; \ return std::move(a); \ } @@ -196,7 +190,8 @@ test9 #define return_a return std::move(a) // Macro test. The std::call is inside the macro, so no fix-it is suggested. -A test10(A a) { +A test10() { + A a; return_a; // expected-warning@-1{{prevents copy elision}} // CHECK-NOT: fix-it Modified: cfe/trunk/test/SemaCXX/warn-redundant-move.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-redundant-move.cpp?rev=242600&r1=242599&r2=242600&view=diff ============================================================================== --- cfe/trunk/test/SemaCXX/warn-redundant-move.cpp (original) +++ cfe/trunk/test/SemaCXX/warn-redundant-move.cpp Fri Jul 17 20:15:19 2015 @@ -90,3 +90,10 @@ C test4(A& a1, B& b1) { return std::move(b1); return std::move(b2); } + +//PR23819 +struct X {}; +X g(); +void h(X&&); +X f(X x) { return std::move(x); } //expected-warning{{redundant move in return statement}} \ + //expected-note{{remove std::move call here}} _______________________________________________ cfe-commits mailing list cfe-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
