[clang] [Clang][Sema] Don't set instantiated from function when rewriting operator<=> (PR #91339)

Krystian Stasiowski via cfe-commits cfe-commits at lists.llvm.org
Tue May 7 08:01:10 PDT 2024


https://github.com/sdkrystian updated https://github.com/llvm/llvm-project/pull/91339

>From b199345e93410ad4e7f7f4b37f09c7e66572d43a Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Tue, 7 May 2024 10:07:26 -0400
Subject: [PATCH 1/4] [Clang][Sema] Don't set instantiated from function when
 rewriting operator<=>

---
 .../lib/Sema/SemaTemplateInstantiateDecl.cpp  | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index d544cfac55ba..37d5d3face08 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2269,16 +2269,18 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
                             TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                              Innermost),
                                                 /*InsertPos=*/nullptr);
-  } else if (isFriend && D->isThisDeclarationADefinition()) {
-    // Do not connect the friend to the template unless it's actually a
-    // definition. We don't want non-template functions to be marked as being
-    // template instantiations.
-    Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
-  } else if (!isFriend) {
-    // If this is not a function template, and this is not a friend (that is,
-    // this is a locally declared function), save the instantiation relationship
-    // for the purposes of constraint instantiation.
-    Function->setInstantiatedFromDecl(D);
+  } else if (FunctionRewriteKind == RewriteKind::None) {
+    if (isFriend && D->isThisDeclarationADefinition()) {
+      // Do not connect the friend to the template unless it's actually a
+      // definition. We don't want non-template functions to be marked as being
+      // template instantiations.
+      Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
+    } else if (!isFriend) {
+      // If this is not a function template, and this is not a friend (that is,
+      // this is a locally declared function), save the instantiation relationship
+      // for the purposes of constraint instantiation.
+      Function->setInstantiatedFromDecl(D);
+    }
   }
 
   if (isFriend) {
@@ -2669,7 +2671,7 @@ Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
                          TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                           Innermost),
                                               /*InsertPos=*/nullptr);
-  } else if (!isFriend) {
+  } else if (!isFriend && FunctionRewriteKind == RewriteKind::None) {
     // Record that this is an instantiation of a member function.
     Method->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
   }

>From 53eef8ed177edef5c4c861472d0a5a7e4bedb072 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Tue, 7 May 2024 10:20:14 -0400
Subject: [PATCH 2/4] [FOLD] add test and release note

---
 clang/docs/ReleaseNotes.rst                           |  3 +++
 .../class/class.compare/class.compare.default/p4.cpp  | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index a85095e424b6..87c4489114c8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -683,6 +683,9 @@ Bug Fixes to C++ Support
 - Fix an assertion failure when parsing an invalid members of an anonymous class. (#GH85447)
 - Fixed a misuse of ``UnresolvedLookupExpr`` for ill-formed templated expressions. Fixes (#GH48673), (#GH63243)
   and (#GH88832).
+- Fix a crash when an implicitly declared ``operator==`` function with a trailing requires-clause has its
+  constraints compared to that of another declaration.
+
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
index 534c3b34d883..a9b2fd2b2230 100644
--- a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
+++ b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
@@ -161,3 +161,14 @@ struct non_constexpr_type {
 
 my_struct<non_constexpr_type> obj; // cxx2a-note {{in instantiation of template class 'GH61238::my_struct<GH61238::non_constexpr_type>' requested here}}
 }
+
+namespace Constrained {
+  template<typename T>
+  struct A {
+    std::strong_ordering operator<=>(const A&) const requires true = default;
+  };
+
+  bool f(A<int> a) {
+    return a != A<int>();
+  }
+}

>From 35140102cade777fffe0abc63c7170039e6b18f4 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Tue, 7 May 2024 10:20:34 -0400
Subject: [PATCH 3/4] [FOLD] format

---
 clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 37d5d3face08..fde2d920c785 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2277,8 +2277,8 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
       Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
     } else if (!isFriend) {
       // If this is not a function template, and this is not a friend (that is,
-      // this is a locally declared function), save the instantiation relationship
-      // for the purposes of constraint instantiation.
+      // this is a locally declared function), save the instantiation
+      // relationship for the purposes of constraint instantiation.
       Function->setInstantiatedFromDecl(D);
     }
   }

>From f30702bbf5a33c28c0544c46b87c46dd7165f87b Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Tue, 7 May 2024 11:00:56 -0400
Subject: [PATCH 4/4] [FOLD] update test

---
 .../class.compare/class.compare.default/p4.cpp   | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
index a9b2fd2b2230..c89718dd71bb 100644
--- a/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
+++ b/clang/test/CXX/class/class.compare/class.compare.default/p4.cpp
@@ -18,14 +18,22 @@ namespace std {
 
 namespace N {
   struct A {
-    friend constexpr std::strong_ordering operator<=>(const A&, const A&) = default;
+    friend constexpr std::strong_ordering operator<=>(const A&, const A&) = default; // expected-note 2{{declared here}}
   };
 
-  constexpr bool (*test_a_not_found)(const A&, const A&) = &operator==; // expected-error {{undeclared}}
+  constexpr std::strong_ordering (*test_a_threeway_not_found)(const A&, const A&) = &operator<=>; // expected-error {{undeclared}}
+
+  constexpr std::strong_ordering operator<=>(const A&, const A&) noexcept;
+  constexpr std::strong_ordering (*test_a_threeway)(const A&, const A&) = &operator<=>;
+  static_assert((*test_a_threeway)(A(), A())); // expected-error {{static assertion expression is not an integral constant expression}}
+                                               // expected-note at -1 {{undefined function 'operator<=>' cannot be used in a constant expression}}
+
+  constexpr bool (*test_a_equal_not_found)(const A&, const A&) = &operator==; // expected-error {{undeclared}}
 
   constexpr bool operator==(const A&, const A&) noexcept;
-  constexpr bool (*test_a)(const A&, const A&) noexcept = &operator==;
-  static_assert((*test_a)(A(), A()));
+  constexpr bool (*test_a_equal)(const A&, const A&) noexcept = &operator==;
+  static_assert((*test_a_equal)(A(), A())); // expected-error {{static assertion expression is not an integral constant expression}}
+                                            // expected-note at -1 {{undefined function 'operator==' cannot be used in a constant expression}}
 }
 
 struct B1 {



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