[clang] Recognize friend operator != to fix ambiguity with operator== (PR #70213)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Wed Oct 25 07:37:30 PDT 2023
https://github.com/usx95 created https://github.com/llvm/llvm-project/pull/70213
The namespace lookup should give a matching friend operator!= as friend functions belong to the namespace scope (as opposed to the lexical class scope).
Thus to resolve ambiguity of operator== with itself, defining a corresponding friend operator!= should suffice.
>From 8aa439a97a56ef80bfc9ccc90a9f093680e455f5 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Sun, 22 Oct 2023 11:11:53 +0200
Subject: [PATCH 1/4] rebase...
---
clang/docs/ReleaseNotes.rst | 4 +
clang/lib/Sema/SemaOverload.cpp | 19 ++---
.../over.match.oper/p3-2a.cpp | 78 +++++++++++++++++++
3 files changed, 89 insertions(+), 12 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3a9a67f7451c092..cef857244387e8b 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -85,6 +85,10 @@ C/C++ Language Potentially Breaking Changes
``__has_c_attribute(warn_unused_result)``, 202003, 0
``__has_c_attribute(gnu::warn_unused_result)``, 202003, 1
+- Fixed a bug in finding matching `operator!=` while adding reversed `operator==` as
+ outlined in "The Equality Operator You Are Looking For" (`P2468 <http://wg21.link/p2468r2>`_).
+ Fixes (`#68901: <https://github.com/llvm/llvm-project/issues/68901>`_).
+
C++ Specific Potentially Breaking Changes
-----------------------------------------
- The name mangling rules for function templates has been changed to take into
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index d57a7ad8f46859a..75e4184c8aa6cb8 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -960,18 +960,13 @@ static bool shouldAddReversedEqEq(Sema &S, SourceLocation OpLoc,
return true;
}
// Otherwise the search scope is the namespace scope of which F is a member.
- LookupResult NonMembers(S, NotEqOp, OpLoc,
- Sema::LookupNameKind::LookupOperatorName);
- S.LookupName(NonMembers,
- S.getScopeForContext(EqFD->getEnclosingNamespaceContext()));
- NonMembers.suppressAccessDiagnostics();
- for (NamedDecl *Op : NonMembers) {
- auto *FD = Op->getAsFunction();
- if(auto* UD = dyn_cast<UsingShadowDecl>(Op))
- FD = UD->getUnderlyingDecl()->getAsFunction();
- if (FunctionsCorrespond(S.Context, EqFD, FD) &&
- declaresSameEntity(cast<Decl>(EqFD->getDeclContext()),
- cast<Decl>(Op->getDeclContext())))
+ for (NamedDecl *Op : EqFD->getEnclosingNamespaceContext()->lookup(NotEqOp)) {
+ auto *NotEqFD = Op->getAsFunction();
+ if (auto *UD = dyn_cast<UsingShadowDecl>(Op))
+ NotEqFD = UD->getUnderlyingDecl()->getAsFunction();
+ if (FunctionsCorrespond(S.Context, EqFD, NotEqFD) &&
+ declaresSameEntity(cast<Decl>(EqFD->getEnclosingNamespaceContext()),
+ cast<Decl>(Op->getLexicalDeclContext())))
return false;
}
return true;
diff --git a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
index 5727d506fe5e61d..9dc5ee8db565341 100644
--- a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
+++ b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
@@ -374,6 +374,84 @@ bool fine(A a, B b) { return a == b; } // Ok. Found a matching operator!=.
}
}
+
+namespace ADL_GH68901{
+namespace A {
+struct S {};
+bool operator==(S, int); // expected-note {{no known conversion from 'int' to 'S' for 1st argument}}
+bool operator!=(S, int);
+} // namespace A
+bool a = 0 == A::S(); // expected-error {{invalid operands to binary expression ('int' and 'A::S')}}
+
+namespace B {
+struct Derived {};
+struct Base : Derived {};
+
+bool operator==(Derived& a, Base& b);
+bool operator!=(Derived& a, Base& b);
+} // namespace B
+
+void foo() {
+ // B::Base{} == B::Base{};
+ B::Base a,b;
+ bool v = a == b;
+}
+
+namespace ns {
+template <class T>
+struct A {
+};
+
+template <class T>
+struct B : A<T> {
+};
+
+template <class T> bool operator == (B<T>, A<T>); // expected-note {{candidate template ignored: could not match 'B' against 'A'}}
+template <class T> bool operator != (B<T>, A<T>);
+}
+
+void test() {
+ ns::A<int> a;
+ ns::B<int> b;
+ a == b; // expected-error {{invalid operands to binary expression}}
+}
+
+
+} //namespace ADL_GH68901
+
+namespace function_scope_operator_eqeq {
+// For non-members, we always lookup for matching operator!= in the namespace scope of
+// operator== (and not in the scope of operator==).
+struct X { operator int(); };
+namespace test1{
+bool h(X x) {
+ bool operator==(X, int); // expected-note {{reversed}}
+ return x == x; // expected-warning {{ambiguous}}
+}
+
+bool g(X x) {
+ bool operator==(X, int); // expected-note {{reversed}}
+ bool operator!=(X, int);
+ return x == x; // expected-warning {{ambiguous}}
+}
+} // namespace test1
+
+namespace test2 {
+bool operator!=(X, int);
+
+bool h(X x) {
+ bool operator==(X, int);
+ return x == x;
+}
+
+bool i(X x) {
+ bool operator==(X, int);
+ bool operator!=(X, int);
+ return x == x;
+}
+} // namespace test2
+} // namespace function_scope_operator_eqeq
+
namespace non_member_template_2 {
struct P {};
template<class S>
>From df6f585d8cd1dbe328733ecb1dde164a312d2f9f Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Sun, 22 Oct 2023 21:27:17 +0200
Subject: [PATCH 2/4] added more test and visibility check.
---
clang/lib/Sema/SemaOverload.cpp | 2 +-
.../over.match.oper/p3-2a.cpp | 49 ++++++++++++++-----
2 files changed, 38 insertions(+), 13 deletions(-)
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 75e4184c8aa6cb8..070e4218ea3afcd 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -964,7 +964,7 @@ static bool shouldAddReversedEqEq(Sema &S, SourceLocation OpLoc,
auto *NotEqFD = Op->getAsFunction();
if (auto *UD = dyn_cast<UsingShadowDecl>(Op))
NotEqFD = UD->getUnderlyingDecl()->getAsFunction();
- if (FunctionsCorrespond(S.Context, EqFD, NotEqFD) &&
+ if (FunctionsCorrespond(S.Context, EqFD, NotEqFD) && S.isVisible(NotEqFD) &&
declaresSameEntity(cast<Decl>(EqFD->getEnclosingNamespaceContext()),
cast<Decl>(Op->getLexicalDeclContext())))
return false;
diff --git a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
index 9dc5ee8db565341..016eaf7f52876d5 100644
--- a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
+++ b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
@@ -376,13 +376,17 @@ bool fine(A a, B b) { return a == b; } // Ok. Found a matching operator!=.
namespace ADL_GH68901{
+namespace test1 {
namespace A {
struct S {};
bool operator==(S, int); // expected-note {{no known conversion from 'int' to 'S' for 1st argument}}
+bool a = 0 == A::S(); // Ok. Operator!= not visible.
bool operator!=(S, int);
} // namespace A
bool a = 0 == A::S(); // expected-error {{invalid operands to binary expression ('int' and 'A::S')}}
+} // namespace test1
+namespace test2 {
namespace B {
struct Derived {};
struct Base : Derived {};
@@ -391,23 +395,20 @@ bool operator==(Derived& a, Base& b);
bool operator!=(Derived& a, Base& b);
} // namespace B
-void foo() {
- // B::Base{} == B::Base{};
+bool foo() {
B::Base a,b;
- bool v = a == b;
+ return a == b;
}
+} // namespace test2
-namespace ns {
-template <class T>
-struct A {
-};
-template <class T>
-struct B : A<T> {
-};
+namespace template_ {
+namespace ns {
+template <class T> struct A {};
+template <class T> struct B : A<T> {};
-template <class T> bool operator == (B<T>, A<T>); // expected-note {{candidate template ignored: could not match 'B' against 'A'}}
-template <class T> bool operator != (B<T>, A<T>);
+template <class T> bool operator==(B<T>, A<T>); // expected-note {{candidate template ignored: could not match 'B' against 'A'}}
+template <class T> bool operator!=(B<T>, A<T>);
}
void test() {
@@ -415,7 +416,31 @@ void test() {
ns::B<int> b;
a == b; // expected-error {{invalid operands to binary expression}}
}
+} // namespace test3
+
+namespace using_not_eq {
+namespace A {
+struct S {};
+namespace B {
+bool operator!=(S, int);
+}
+bool operator==(S, int); // expected-note {{candidate}}
+using B::operator!=;
+} // namespace A
+bool a = 0 == A::S(); // expected-error {{invalid operands to binary expression}}
+} // namespace reversed_lookup_not_like_ADL
+namespace using_eqeq {
+namespace A {
+struct S {};
+namespace B {
+bool operator==(S, int); // expected-note {{candidate}}
+bool operator!=(S, int);
+}
+using B::operator==;
+} // namespace A
+bool a = 0 == A::S(); // expected-error {{invalid operands to binary expression}}
+}
} //namespace ADL_GH68901
>From 24e874ca5e6f1b4ac58068cbfb68cbb48fd5e2e3 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Mon, 23 Oct 2023 14:04:42 +0200
Subject: [PATCH 3/4] added test for visibility
---
.../over.match.oper/p2468R2.cppm | 24 +++++++++++++++++++
1 file changed, 24 insertions(+)
create mode 100644 clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p2468R2.cppm
diff --git a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p2468R2.cppm b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p2468R2.cppm
new file mode 100644
index 000000000000000..05891618991da07
--- /dev/null
+++ b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p2468R2.cppm
@@ -0,0 +1,24 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/A.cppm -emit-module-interface -o %t/A.pcm
+// RUN: %clang_cc1 -std=c++20 -fprebuilt-module-path=%t -I%t %t/p2468r2.cpp -verify
+
+//--- A.cppm
+module;
+export module A;
+export {
+namespace NS {
+struct S {};
+bool operator==(S, int);
+} // namespace NS
+}
+
+namespace NS { bool operator!=(S, int); } // Not visible.
+
+
+//--- p2468r2.cpp
+// expected-no-diagnostics
+import A;
+bool x = 0 == NS::S(); // Ok. operator!= from module A is not visible.
>From 183209f71b08a1fdba335d89c906cd26483115c1 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 25 Oct 2023 16:32:52 +0200
Subject: [PATCH 4/4] friend operator!=
---
clang/lib/Sema/SemaOverload.cpp | 18 ++++++++++-----
.../over.match.oper/p3-2a.cpp | 22 +++++++++++++++++++
2 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 070e4218ea3afcd..30bde49636b2f69 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -14,6 +14,7 @@
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclFriend.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DependenceFlags.h"
#include "clang/AST/Expr.h"
@@ -960,13 +961,16 @@ static bool shouldAddReversedEqEq(Sema &S, SourceLocation OpLoc,
return true;
}
// Otherwise the search scope is the namespace scope of which F is a member.
- for (NamedDecl *Op : EqFD->getEnclosingNamespaceContext()->lookup(NotEqOp)) {
+ DeclContext *EqDC = EqFD->getEnclosingNamespaceContext();
+ for (NamedDecl *Op : EqDC->lookup(NotEqOp)) {
auto *NotEqFD = Op->getAsFunction();
+ DeclContext *NotEqDC = Op->getFriendObjectKind()
+ ? NotEqFD->getEnclosingNamespaceContext()
+ : Op->getLexicalDeclContext();
if (auto *UD = dyn_cast<UsingShadowDecl>(Op))
NotEqFD = UD->getUnderlyingDecl()->getAsFunction();
if (FunctionsCorrespond(S.Context, EqFD, NotEqFD) && S.isVisible(NotEqFD) &&
- declaresSameEntity(cast<Decl>(EqFD->getEnclosingNamespaceContext()),
- cast<Decl>(Op->getLexicalDeclContext())))
+ declaresSameEntity(cast<Decl>(EqDC), cast<Decl>(NotEqDC)))
return false;
}
return true;
@@ -10086,9 +10090,11 @@ static bool allowAmbiguity(ASTContext &Context, const FunctionDecl *F1,
const FunctionDecl *F2) {
if (declaresSameEntity(F1, F2))
return true;
- if (F1->isTemplateInstantiation() && F2->isTemplateInstantiation() &&
- declaresSameEntity(F1->getPrimaryTemplate(), F2->getPrimaryTemplate())) {
- return true;
+ if (F1->isTemplateInstantiation() && F2->isTemplateInstantiation()) {
+ FunctionTemplateDecl *P1 = F1->getPrimaryTemplate();
+ FunctionTemplateDecl *P2 = F2->getPrimaryTemplate();
+ if (declaresSameEntity(P1, P2))
+ return true;
}
// TODO: It is not clear whether comparing parameters is necessary (i.e.
// different functions with same params). Consider removing this (as no test
diff --git a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
index 016eaf7f52876d5..2292822e230dde6 100644
--- a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
+++ b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp
@@ -374,6 +374,28 @@ bool fine(A a, B b) { return a == b; } // Ok. Found a matching operator!=.
}
}
+namespace friend_opNE_GH{
+namespace test1 {
+struct S {
+ operator int();
+ friend bool operator==(const S &, int); // expected-note {{reversed}}
+};
+struct A : S {};
+struct B : S {};
+bool x = A{} == B{}; // expected-warning {{ambiguous}}
+}
+
+namespace test2 {
+struct S {
+ operator int();
+ friend bool operator==(const S &, int);
+ friend bool operator!=(const S &, int);
+};
+struct A : S {};
+struct B : S {};
+bool x = A{} == B{};
+}
+}
namespace ADL_GH68901{
namespace test1 {
More information about the cfe-commits
mailing list