Commit e5ab1e49 authored by Mark de Wever's avatar Mark de Wever
Browse files

Improve Wrange-loop-analyses for rvalue reference 

The Wrange-loop-analyses warns if a copy is made. Suppress this warning when
a temporary is bound to a rvalue reference.

While fixing this issue also found a copy-paste error in test6, which is also
fixed.

Differential Revision: https://reviews.llvm.org/D71806
parent f022a5a7

clang/lib/Sema/SemaStmt.cpp

+3 −1
Original line number Diff line number Diff line
@@ -2764,9 +2764,11 @@ static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef, 
    SemaRef.Diag(VD->getBeginLoc(), diag::note_use_type_or_non_reference)

        << NonReferenceType << NewReferenceType << VD->getSourceRange()

        << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());

  } else {

  } else if (!VariableType->isRValueReferenceType()) {

    // The range always returns a copy, so a temporary is always created.

    // Suggest removing the reference from the loop variable.

    // If the type is a rvalue reference do not warn since that changes the

    // semantic of the code.

    SemaRef.Diag(VD->getLocation(), diag::warn_for_range_variable_always_copy)

        << VD << RangeInitType;

    QualType NonReferenceType = VariableType.getNonReferenceType();

clang/test/SemaCXX/warn-range-loop-analysis.cpp

+110 −2
Original line number Diff line number Diff line
@@ -84,34 +84,46 @@ void test0() { 
void test1() {

  Container<int> A;



  for (const int &&x : A) {}

  // No warning, rvalue-reference to the temporary

  for (const int &x : A) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'int'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const int x : A) {}

  // No warning, non-reference type indicates copy is made

  for (int&& x : A) {}

  // No warning, rvalue-reference to the temporary

  //for (int &x : A) {}

  // Binding error

  for (int x : A) {}

  // No warning, non-reference type indicates copy is made



  for (const double &&x : A) {}

  // No warning, rvalue-reference to the temporary

  for (const double &x : A) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'double'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:21-[[@LINE-3]]:22}:""

  for (const double x : A) {}

  // No warning, non-reference type indicates copy is made

  for (double &&x : A) {}

  // No warning, rvalue-reference to the temporary

  //for (double &x : A) {}

  // Binding error

  for (double x : A) {}

  // No warning, non-reference type indicates copy is made



  for (const Bar &&x : A) {}

  // No warning, rvalue-reference to the temporary

  for (const Bar &x : A) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : A) {}

  // No warning, non-reference type indicates copy is made

  for (Bar &&x : A) {}

  // No warning, rvalue-reference to the temporary

  //for (Bar &x : A) {}

  // Binding error

  for (Bar x : A) {}
@@ -121,30 +133,50 @@ void test1() { 
void test2() {

  Container<int&> B;



  //for (const int &&x : B) {}

  // Binding error

  for (const int &x : B) {}

  // No warning, this reference is not a temporary

  for (const int x : B) {}

  // No warning on POD copy

  //for (int &x : B) {}

  // Binding error

  for (int &x : B) {}

  // No warning

  for (int x : B) {}

  // No warning



  for (const double &&x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'double'{{.*}}'const int &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:21-[[@LINE-3]]:23}:""

  for (const double &x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'double'{{.*}}'const int &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:21-[[@LINE-3]]:22}:""

  for (const double x : B) {}

  for (double &&x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'double'{{.*}}'const int &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:15-[[@LINE-3]]:17}:""

  //for (double &x : B) {}

  // Binding error

  for (double x : B) {}

  // No warning



  for (const Bar &&x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const Bar &x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : B) {}

  for (Bar &&x : B) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (Bar &x : B) {}

  // Binding error

  for (Bar x : B) {}
@@ -154,23 +186,31 @@ void test2() { 
void test3() {

  Container<Bar> C;



  for (const Bar &&x : C) {}

  // No warning, rvalue-reference to the temporary

  for (const Bar &x : C) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : C) {}

  // No warning, non-reference type indicates copy is made

  for (Bar &&x : C) {}

  // No warning, rvalue-reference to the temporary

  //for (Bar &x : C) {}

  // Binding error

  for (Bar x : C) {}

  // No warning, non-reference type indicates copy is made



  for (const int &&x : C) {}

  // No warning, rvalue-reference to the temporary

  for (const int &x : C) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'int'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const int x : C) {}

  // No warning, copy made

  for (int &&x : C) {}

  // No warning, rvalue-reference to the temporary

  //for (int &x : C) {}

  // Binding error

  for (int x : C) {}
@@ -180,23 +220,35 @@ void test3() { 
void test4() {

  Container<Bar&> D;



  //for (const Bar &&x : D) {}

  // Binding error

  for (const Bar &x : D) {}

  // No warning, this reference is not a temporary

  for (const Bar x : D) {}

  // expected-warning@-1 {{creates a copy}}

  // expected-note@-2 {{'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:18}:"&"

  //for (Bar &&x : D) {}

  // Binding error

  for (Bar &x : D) {}

  // No warning

  for (Bar x : D) {}

  // No warning



  for (const int &&x : D) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const int &x : D) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const int x : D) {}

  // No warning

  for (int &&x : D) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (int &x : D) {}

  // Binding error

  for (int x : D) {}
@@ -206,12 +258,16 @@ void test4() { 
void test5() {

  Container<Foo> E;



  for (const Bar &&x : E) {}

  // No warning, rvalue-reference to the temporary

  for (const Bar &x : E) {}

  // expected-warning@-1 {{always a copy}}

  // expected-note@-2 {{'Bar'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : E) {}

  // No warning, non-reference type indicates copy is made

  for (Bar &&x : E) {}

  // No warning, rvalue-reference to the temporary

  //for (Bar &x : E) {}

  // Binding error

  for (Bar x : E) {}
@@ -221,12 +277,20 @@ void test5() { 
void test6() {

  Container<Foo&> F;



  for (const Bar &&x : F) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const Bar &x : F) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : F) {}

  // No warning.

  for (Bar &&x : F) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (Bar &x : F) {}

  // Binding error

  for (Bar x : F) {}
@@ -236,56 +300,88 @@ void test6() { 
void test7() {

  double G[2];



  //for (const double &&x : G) {}

  // Binding error

  for (const double &x : G) {}

  // No warning

  for (const double x : G) {}

  // No warning on POD copy

  //for (double &&x : G) {}

  // Binding error

  for (double &x : G) {}

  // No warning

  for (double x : G) {}

  // No warning



  for (const int &&x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const int &x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const int x : G) {}

  // No warning

  for (int &&x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (int &x : G) {}

  // Binding error

  for (int x : G) {}

  // No warning



  for (const Bar &&x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const Bar &x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : G) {}

  // No warning

  //for (int &Bar : G) {}

  for (Bar &&x : G) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const double &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (Bar &x : G) {}

  // Binding error

  for (int Bar : G) {}

  for (Bar x : G) {}

  // No warning

}



void test8() {

  Foo H[2];



  //for (const Foo &&x : H) {}

  // Binding error

  for (const Foo &x : H) {}

  // No warning

  for (const Foo x : H) {}

  // No warning on POD copy

  //for (Foo &&x : H) {}

  // Binding error

  for (Foo &x : H) {}

  // No warning

  for (Foo x : H) {}

  // No warning



  for (const Bar &&x : H) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const Bar &x : H) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const Bar x : H) {}

  // No warning

  for (Bar &&x: H) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'Bar'{{.*}}'const Foo &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (Bar &x: H) {}

  // Binding error

  for (Bar x: H) {}
@@ -295,23 +391,35 @@ void test8() { 
void test9() {

  Bar I[2] = {1,2};



  //for (const Bar &&x : I) {}

  // Binding error

  for (const Bar &x : I) {}

  // No warning

  for (const Bar x : I) {}

  // expected-warning@-1 {{creates a copy}}

  // expected-note@-2 {{'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:18}:"&"

  //for (Bar &&x : I) {}

  // Binding error

  for (Bar &x : I) {}

  // No warning

  for (Bar x : I) {}

  // No warning



  for (const int &&x : I) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:20}:""

  for (const int &x : I) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:18-[[@LINE-3]]:19}:""

  for (const int x : I) {}

  // No warning

  for (int &&x : I) {}

  // expected-warning@-1 {{resulting in a copy}}

  // expected-note-re@-2 {{'int'{{.*}}'const Bar &'}}

  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:12-[[@LINE-3]]:14}:""

  //for (int &x : I) {}

  // Binding error

  for (int x : I) {}