https://github.com/sdkrystian updated
https://github.com/llvm/llvm-project/pull/72863
>From 7b26c6ea5f3c75f1146df21f51c1f40967aaae98 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkryst...@gmail.com>
Date: Mon, 20 Nov 2023 07:11:41 -0500
Subject: [PATCH] [Clang][Sema] Diagnose friend function specialization
definitions
---
clang/docs/ReleaseNotes.rst | 1 +
.../clang/Basic/DiagnosticSemaKinds.td | 2 +
clang/lib/AST/Decl.cpp | 1 +
clang/lib/Sema/SemaDeclCXX.cpp | 71 +++++++++----------
.../test/CXX/class.access/class.friend/p6.cpp | 13 ++++
.../CXX/temp/temp.decls/temp.friend/p1.cpp | 6 +-
clang/test/SemaCXX/friend.cpp | 2 +-
7 files changed, 55 insertions(+), 41 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b4b5352a306c1c..bc3acf165f0759 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -513,6 +513,7 @@ Improvements to Clang's diagnostics
48 | static_assert(1 << 4 == 15);
| ~~~~~~~^~~~~
+- Clang now diagnoses definitions of friend function specializations, e.g.
``friend void f<>(int) {}``.
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 28d95ca9b13893..0b53c6dce810f8 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1669,6 +1669,8 @@ def err_qualified_friend_def : Error<
"friend function definition cannot be qualified with '%0'">;
def err_friend_def_in_local_class : Error<
"friend function cannot be defined in a local class">;
+def err_friend_specialization_def : Error<
+ "friend function specialization cannot be defined">;
def err_friend_not_first_in_declaration : Error<
"'friend' must appear first in a non-function declaration">;
def err_using_decl_friend : Error<
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index c5c2edf1bfe3ab..527ea6042daa03 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4150,6 +4150,7 @@
FunctionDecl::setFunctionTemplateSpecialization(ASTContext &C,
assert(TSK != TSK_Undeclared &&
"Must specify the type of function template specialization");
assert((TemplateOrSpecialization.isNull() ||
+ getFriendObjectKind() != FOK_None ||
TSK == TSK_ExplicitSpecialization) &&
"Member specialization must be an explicit specialization");
FunctionTemplateSpecializationInfo *Info =
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index c6218a491aecec..36e53c684ac4dc 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -17879,6 +17879,8 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S,
Declarator &D,
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForExternalRedeclaration);
+ bool isTemplateId = D.getName().getKind() ==
UnqualifiedIdKind::IK_TemplateId;
+
// There are five cases here.
// - There's no scope specifier and we're in a local class. Only look
// for functions declared in the immediately-enclosing block scope.
@@ -17916,14 +17918,6 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S,
Declarator &D,
}
adjustContextForLocalExternDecl(DC);
- // C++ [class.friend]p6:
- // A function can be defined in a friend declaration of a class if and
- // only if the class is a non-local class (9.8), the function name is
- // unqualified, and the function has namespace scope.
- if (D.isFunctionDefinition()) {
- Diag(NameInfo.getBeginLoc(), diag::err_friend_def_in_local_class);
- }
-
// - There's no scope specifier, in which case we just go to the
// appropriate scope and look for a function or function template
// there as appropriate.
@@ -17934,8 +17928,6 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S,
Declarator &D,
// elaborated-type-specifier, the lookup to determine whether
// the entity has been previously declared shall not consider
// any scopes outside the innermost enclosing namespace.
- bool isTemplateId =
- D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId;
// Find the appropriate context according to the above.
DC = CurContext;
@@ -17988,39 +17980,12 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S,
Declarator &D,
diag::warn_cxx98_compat_friend_is_member :
diag::err_friend_is_member);
- if (D.isFunctionDefinition()) {
- // C++ [class.friend]p6:
- // A function can be defined in a friend declaration of a class if and
- // only if the class is a non-local class (9.8), the function name is
- // unqualified, and the function has namespace scope.
- //
- // FIXME: We should only do this if the scope specifier names the
- // innermost enclosing namespace; otherwise the fixit changes the
- // meaning of the code.
- SemaDiagnosticBuilder DB
- = Diag(SS.getRange().getBegin(), diag::err_qualified_friend_def);
-
- DB << SS.getScopeRep();
- if (DC->isFileContext())
- DB << FixItHint::CreateRemoval(SS.getRange());
- SS.clear();
- }
-
// - There's a scope specifier that does not match any template
// parameter lists, in which case we use some arbitrary context,
// create a method or method template, and wait for instantiation.
// - There's a scope specifier that does match some template
// parameter lists, which we don't handle right now.
} else {
- if (D.isFunctionDefinition()) {
- // C++ [class.friend]p6:
- // A function can be defined in a friend declaration of a class if and
- // only if the class is a non-local class (9.8), the function name is
- // unqualified, and the function has namespace scope.
- Diag(SS.getRange().getBegin(), diag::err_qualified_friend_def)
- << SS.getScopeRep();
- }
-
DC = CurContext;
assert(isa<CXXRecordDecl>(DC) && "friend declaration not in class?");
}
@@ -18105,6 +18070,38 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S,
Declarator &D,
else
FD = cast<FunctionDecl>(ND);
+ // C++ [class.friend]p6:
+ // A function may be defined in a friend declaration of a class if and
+ // only if the class is a non-local class, and the function name is
+ // unqualified.
+ if (D.isFunctionDefinition()) {
+ // Qualified friend function definition.
+ if (SS.isNotEmpty()) {
+ // FIXME: We should only do this if the scope specifier names the
+ // innermost enclosing namespace; otherwise the fixit changes the
+ // meaning of the code.
+ SemaDiagnosticBuilder DB =
+ Diag(SS.getRange().getBegin(), diag::err_qualified_friend_def);
+
+ DB << SS.getScopeRep();
+ if (DC->isFileContext())
+ DB << FixItHint::CreateRemoval(SS.getRange());
+
+ // Friend function defined in a local class.
+ } else if (FunctionContainingLocalClass) {
+ Diag(NameInfo.getBeginLoc(), diag::err_friend_def_in_local_class);
+
+ // Per [basic.pre]p4, a template-id is not a name. Therefore, if we
have
+ // a template-id, the function name is not unqualified because these is
+ // no name. While the wording requires some reading in-between the
+ // lines, GCC, MSVC, and EDG all consider a friend function
+ // specialization definitions // to be de facto explicit specialization
+ // and diagnose them as such.
+ } else if (isTemplateId) {
+ Diag(NameInfo.getBeginLoc(), diag::err_friend_specialization_def);
+ }
+ }
+
// C++11 [dcl.fct.default]p4: If a friend declaration specifies a
// default argument expression, that declaration shall be a definition
// and shall be the only declaration of the function or function
diff --git a/clang/test/CXX/class.access/class.friend/p6.cpp
b/clang/test/CXX/class.access/class.friend/p6.cpp
index 2fe20fe77fc8f2..47104e29dc6b3c 100644
--- a/clang/test/CXX/class.access/class.friend/p6.cpp
+++ b/clang/test/CXX/class.access/class.friend/p6.cpp
@@ -22,3 +22,16 @@ void local() {
friend void f() { } // expected-error{{friend function cannot be defined
in a local class}}
};
}
+
+template<typename T> void f3(T);
+
+namespace N {
+ template<typename T> void f4(T);
+}
+
+template<typename T> struct A {
+ friend void f3(T) {}
+ friend void f3<T>(T) {} // expected-error{{friend function specialization
cannot be defined}}
+ friend void N::f4(T) {} // expected-error{{friend function definition cannot
be qualified with 'N::'}}
+ friend void N::f4<T>(T) {} // expected-error{{friend function definition
cannot be qualified with 'N::'}}
+};
diff --git a/clang/test/CXX/temp/temp.decls/temp.friend/p1.cpp
b/clang/test/CXX/temp/temp.decls/temp.friend/p1.cpp
index ab1b9f7a73eec8..1cf9e1c9f9c0fa 100644
--- a/clang/test/CXX/temp/temp.decls/temp.friend/p1.cpp
+++ b/clang/test/CXX/temp/temp.decls/temp.friend/p1.cpp
@@ -17,7 +17,7 @@ template <typename T> struct Num {
for (U count = n.count_; count; --count)
x += a;
return x;
- }
+ }
};
friend Num operator+(const Num &a, const Num &b) {
@@ -145,7 +145,7 @@ namespace test5 {
namespace Dependent {
template<typename T, typename Traits> class X;
- template<typename T, typename Traits>
+ template<typename T, typename Traits>
X<T, Traits> operator+(const X<T, Traits>&, const T*);
template<typename T, typename Traits> class X {
@@ -249,7 +249,7 @@ namespace test11 {
};
template struct Foo::IteratorImpl<int>;
- template struct Foo::IteratorImpl<long>;
+ template struct Foo::IteratorImpl<long>;
}
// PR6827
diff --git a/clang/test/SemaCXX/friend.cpp b/clang/test/SemaCXX/friend.cpp
index 367d6a6c1807c9..53e6bbfcf42a8e 100644
--- a/clang/test/SemaCXX/friend.cpp
+++ b/clang/test/SemaCXX/friend.cpp
@@ -162,7 +162,7 @@ namespace test9 {
class C {
};
struct A {
- friend void C::f(int, int, int) {} // expected-error {{friend function
definition cannot be qualified with 'C::'}}
+ friend void C::f(int, int, int) {} // expected-error {{friend declaration
of 'f' does not match any declaration in 'test9::C'}}
};
}
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