https://github.com/Sirraide created
https://github.com/llvm/llvm-project/pull/105121
Diagnose this early after parsing declaration specifiers; this allows us to
issue a better diagnostic. This also checks for `concept friend` and concept
declarations w/o a template-head because it’s easiest to do that at the same
time.
Fixes #45182.
>From 1cc581a3b3af057793c11a862b8facfba2aef926 Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalm...@gmail.com>
Date: Tue, 20 Aug 2024 18:40:18 +0200
Subject: [PATCH 1/4] [Clang] [Parser] Improve diagnostic for 'friend concept'
---
clang/include/clang/Basic/DiagnosticParseKinds.td | 3 +++
clang/lib/Parse/ParseDeclCXX.cpp | 9 +++++++++
clang/test/Parser/friend-concept.cpp | 11 +++++++++++
3 files changed, 23 insertions(+)
create mode 100644 clang/test/Parser/friend-concept.cpp
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td
b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 62a97b36737e72..953d40b8e5fa56 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -971,6 +971,9 @@ def warn_cxx23_variadic_friends : Warning<
"variadic 'friend' declarations are incompatible with C++ standards before
C++2c">,
DefaultIgnore, InGroup<CXXPre26Compat>;
+def err_friend_concept : Error<
+ "friend declaration cannot be a concept">;
+
// C++11 default member initialization
def ext_nonstatic_member_init : ExtWarn<
"default member initializer for non-static data member is a C++11 "
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 18c5fe6056b472..400745fd73fd9b 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -3139,6 +3139,15 @@ Parser::DeclGroupPtrTy
Parser::ParseCXXClassMemberDeclaration(
return Actions.BuildDeclaratorGroup(Decls);
}
+ // Befriending a concept is invalid and would already fail if
+ // we did nothing here, but this allows us to issue a more
+ // helpful diagnostic.
+ if (Tok.is(tok::kw_concept)) {
+ Diag(Tok.getLocation(), diag::err_friend_concept);
+ SkipUntil(tok::semi, tok::r_brace, StopBeforeMatch);
+ return nullptr;
+ }
+
ParsingDeclarator DeclaratorInfo(*this, DS, DeclAttrs,
DeclaratorContext::Member);
if (TemplateInfo.TemplateParams)
diff --git a/clang/test/Parser/friend-concept.cpp
b/clang/test/Parser/friend-concept.cpp
new file mode 100644
index 00000000000000..d032a31b1de9bd
--- /dev/null
+++ b/clang/test/Parser/friend-concept.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
+
+template<class>
+concept fooable = true;
+
+struct S {
+ template<class> friend concept fooable; // expected-error {{friend
declaration cannot be a concept}}
+ template<class> concept friend fooable; // expected-error {{expected
unqualified-id}}
+ friend concept fooable; // expected-error {{friend declaration cannot be a
concept}}
+ concept friend fooable; // expected-error {{friend declaration cannot be a
concept}}
+};
>From fe042f6a37c9cf4c735e0a973f9fdfbb38492ebd Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalm...@gmail.com>
Date: Tue, 20 Aug 2024 18:43:51 +0200
Subject: [PATCH 2/4] Add release note
---
clang/docs/ReleaseNotes.rst | 2 ++
1 file changed, 2 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index e3fac712de4662..7fd856a8e6d16b 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -233,6 +233,8 @@ Improvements to Clang's diagnostics
- Clang now diagnoses when the result of a [[nodiscard]] function is discarded
after being cast in C. Fixes #GH104391.
+- Improved diagnostic when trying to befriend a concept. (#GH45182).
+
Improvements to Clang's time-trace
----------------------------------
>From c329d5d6d630be3a7705804df8d22e775a10e073 Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalm...@gmail.com>
Date: Tue, 20 Aug 2024 18:50:20 +0200
Subject: [PATCH 3/4] Not every declaration in a class is a friend
---
clang/lib/Parse/ParseDeclCXX.cpp | 6 +++++-
clang/test/Parser/friend-concept.cpp | 2 +-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 400745fd73fd9b..9e8e5c90721c8d 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -3143,7 +3143,11 @@ Parser::DeclGroupPtrTy
Parser::ParseCXXClassMemberDeclaration(
// we did nothing here, but this allows us to issue a more
// helpful diagnostic.
if (Tok.is(tok::kw_concept)) {
- Diag(Tok.getLocation(), diag::err_friend_concept);
+ Diag(Tok.getLocation(),
+ DS.isFriendSpecified()
+ ? diag::err_friend_concept
+ : diag::
+
err_concept_decls_may_only_appear_in_global_namespace_scope);
SkipUntil(tok::semi, tok::r_brace, StopBeforeMatch);
return nullptr;
}
diff --git a/clang/test/Parser/friend-concept.cpp
b/clang/test/Parser/friend-concept.cpp
index d032a31b1de9bd..66536a1bd4ad9d 100644
--- a/clang/test/Parser/friend-concept.cpp
+++ b/clang/test/Parser/friend-concept.cpp
@@ -7,5 +7,5 @@ struct S {
template<class> friend concept fooable; // expected-error {{friend
declaration cannot be a concept}}
template<class> concept friend fooable; // expected-error {{expected
unqualified-id}}
friend concept fooable; // expected-error {{friend declaration cannot be a
concept}}
- concept friend fooable; // expected-error {{friend declaration cannot be a
concept}}
+ concept friend fooable; // expected-error {{concept declarations may only
appear in global or namespace scope}}
};
>From 8d09f2a02a089b28d4ea177970724e964b9ef43d Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalm...@gmail.com>
Date: Tue, 20 Aug 2024 19:00:06 +0200
Subject: [PATCH 4/4] Also check for 'concept friend'
---
clang/lib/Parse/ParseDeclCXX.cpp | 2 +-
clang/test/Parser/friend-concept.cpp | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 9e8e5c90721c8d..7ca27d00c0bcbf 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -3144,7 +3144,7 @@ Parser::DeclGroupPtrTy
Parser::ParseCXXClassMemberDeclaration(
// helpful diagnostic.
if (Tok.is(tok::kw_concept)) {
Diag(Tok.getLocation(),
- DS.isFriendSpecified()
+ DS.isFriendSpecified() || NextToken().is(tok::kw_friend)
? diag::err_friend_concept
: diag::
err_concept_decls_may_only_appear_in_global_namespace_scope);
diff --git a/clang/test/Parser/friend-concept.cpp
b/clang/test/Parser/friend-concept.cpp
index 66536a1bd4ad9d..d771ca4d4178ed 100644
--- a/clang/test/Parser/friend-concept.cpp
+++ b/clang/test/Parser/friend-concept.cpp
@@ -4,8 +4,10 @@ template<class>
concept fooable = true;
struct S {
+ template<class> friend concept x = requires { requires true; }; //
expected-error {{friend declaration cannot be a concept}}
template<class> friend concept fooable; // expected-error {{friend
declaration cannot be a concept}}
template<class> concept friend fooable; // expected-error {{expected
unqualified-id}}
friend concept fooable; // expected-error {{friend declaration cannot be a
concept}}
- concept friend fooable; // expected-error {{concept declarations may only
appear in global or namespace scope}}
+ concept friend fooable; // expected-error {{friend declaration cannot be a
concept}}
+ concept fooable; // expected-error {{concept declarations may only appear in
global or namespace scope}}
};
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