[clang] [clang] Implement CWG2877 "Type-only lookup for using-enum-declarator" (PR #95399)
Vlad Serebrennikov via cfe-commits
cfe-commits at lists.llvm.org
Thu Jun 20 05:38:49 PDT 2024
https://github.com/Endilll updated https://github.com/llvm/llvm-project/pull/95399
>From a7b6a8b667d48d8e70f3e5fcbaaa44a72ad885db Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 13 Jun 2024 14:35:08 +0300
Subject: [PATCH 1/5] [clang] Implement CWG2877 "Type-only lookup for
using-enum-declarator"
---
clang/include/clang/Sema/Sema.h | 2 +-
clang/lib/Parse/ParseDeclCXX.cpp | 44 +++++++++++++++++++++----
clang/lib/Sema/SemaDeclCXX.cpp | 19 ++++++-----
clang/test/CXX/drs/cwg26xx.cpp | 5 ++-
clang/test/CXX/drs/cwg28xx.cpp | 10 ++----
clang/test/SemaCXX/cxx20-using-enum.cpp | 12 ++++---
clang/www/cxx_dr_status.html | 10 ++++--
7 files changed, 70 insertions(+), 32 deletions(-)
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 4d4579fcfd456..ccabd4925b8a3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -4032,7 +4032,7 @@ class Sema final : public SemaBase {
Decl *ActOnUsingEnumDeclaration(Scope *CurScope, AccessSpecifier AS,
SourceLocation UsingLoc,
SourceLocation EnumLoc,
- SourceLocation IdentLoc, IdentifierInfo &II,
+ SourceRange TyLoc, const IdentifierInfo &II, ParsedType Ty,
CXXScopeSpec *SS = nullptr);
Decl *ActOnAliasDeclaration(Scope *CurScope, AccessSpecifier AS,
MultiTemplateParamsArg TemplateParams,
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 9a4a777f575b2..189fcc5440292 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -692,7 +692,7 @@ bool Parser::ParseUsingDeclarator(DeclaratorContext Context,
/// using-enum-declaration: [C++20, dcl.enum]
/// 'using' elaborated-enum-specifier ;
/// The terminal name of the elaborated-enum-specifier undergoes
-/// ordinary lookup
+/// type-only lookup
///
/// elaborated-enum-specifier:
/// 'enum' nested-name-specifier[opt] identifier
@@ -738,16 +738,48 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
return nullptr;
}
- if (!Tok.is(tok::identifier)) {
+ Decl *UED = nullptr;
+
+ if (Tok.is(tok::identifier)) {
+ IdentifierInfo *IdentInfo = Tok.getIdentifierInfo();
+ SourceLocation IdentLoc = ConsumeToken();
+
+ ParsedType Type = Actions.getTypeName(*IdentInfo, IdentLoc, getCurScope(), &SS, /*isClassName=*/true,
+ /*HasTrailingDot=*/false,
+ /*ObjectType=*/nullptr, /*IsCtorOrDtorName=*/false,
+ /*WantNontrivialTypeSourceInfo=*/true);
+
+ UED = Actions.ActOnUsingEnumDeclaration(
+ getCurScope(), AS, UsingLoc, UELoc, IdentLoc, *IdentInfo, Type, &SS);
+ }
+ else if (Tok.is(tok::annot_template_id)) {
+ TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
+
+ if (TemplateId->mightBeType()) {
+ AnnotateTemplateIdTokenAsType(SS, ImplicitTypenameContext::No,
+ /*IsClassName=*/true);
+
+ assert(Tok.is(tok::annot_typename) && "template-id -> type failed");
+ TypeResult Type = getTypeAnnotation(Tok);
+ SourceRange Loc = Tok.getAnnotationRange();
+ ConsumeAnnotationToken();
+
+ UED = Actions.ActOnUsingEnumDeclaration(
+ getCurScope(), AS, UsingLoc, UELoc, Loc, *TemplateId->Name, Type.get(), &SS);
+ }
+ else {
+ Diag(Tok.getLocation(), diag::err_using_enum_not_enum)
+ << TemplateId->Name->getName()
+ << SourceRange(TemplateId->TemplateNameLoc, TemplateId->RAngleLoc);
+ }
+ }
+ else {
Diag(Tok.getLocation(), diag::err_using_enum_expect_identifier)
<< Tok.is(tok::kw_enum);
SkipUntil(tok::semi);
return nullptr;
}
- IdentifierInfo *IdentInfo = Tok.getIdentifierInfo();
- SourceLocation IdentLoc = ConsumeToken();
- Decl *UED = Actions.ActOnUsingEnumDeclaration(
- getCurScope(), AS, UsingLoc, UELoc, IdentLoc, *IdentInfo, &SS);
+
if (!UED) {
SkipUntil(tok::semi);
return nullptr;
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 37f0df2a6a27d..fb9e38d6b5bc9 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -12395,22 +12395,23 @@ Decl *Sema::ActOnUsingDeclaration(Scope *S, AccessSpecifier AS,
Decl *Sema::ActOnUsingEnumDeclaration(Scope *S, AccessSpecifier AS,
SourceLocation UsingLoc,
SourceLocation EnumLoc,
- SourceLocation IdentLoc,
- IdentifierInfo &II, CXXScopeSpec *SS) {
+ SourceRange TyLoc, const IdentifierInfo &II,
+ ParsedType Ty, CXXScopeSpec *SS) {
assert(!SS->isInvalid() && "ScopeSpec is invalid");
TypeSourceInfo *TSI = nullptr;
- QualType EnumTy = GetTypeFromParser(
- getTypeName(II, IdentLoc, S, SS, /*isClassName=*/false,
- /*HasTrailingDot=*/false,
- /*ObjectType=*/nullptr, /*IsCtorOrDtorName=*/false,
- /*WantNontrivialTypeSourceInfo=*/true),
- &TSI);
+ SourceLocation IdentLoc = TyLoc.getBegin();
+ QualType EnumTy = GetTypeFromParser(Ty, &TSI);
if (EnumTy.isNull()) {
Diag(IdentLoc, SS && isDependentScopeSpecifier(*SS)
? diag::err_using_enum_is_dependent
: diag::err_unknown_typename)
<< II.getName()
- << SourceRange(SS ? SS->getBeginLoc() : IdentLoc, IdentLoc);
+ << SourceRange(SS ? SS->getBeginLoc() : IdentLoc, TyLoc.getEnd());
+ return nullptr;
+ }
+
+ if (EnumTy->isDependentType()) {
+ Diag(IdentLoc, diag::err_using_enum_is_dependent);
return nullptr;
}
diff --git a/clang/test/CXX/drs/cwg26xx.cpp b/clang/test/CXX/drs/cwg26xx.cpp
index 2b17c8101438d..e180c93011a7e 100644
--- a/clang/test/CXX/drs/cwg26xx.cpp
+++ b/clang/test/CXX/drs/cwg26xx.cpp
@@ -7,7 +7,7 @@
// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown -pedantic-errors %s -verify=expected,since-cxx11,since-cxx20,since-cxx23
-namespace cwg2621 { // cwg2621: 16
+namespace cwg2621 { // cwg2621: sup 2877
#if __cplusplus >= 202002L
enum class E { a };
namespace One {
@@ -17,9 +17,8 @@ auto v = a;
}
namespace Two {
using cwg2621::E;
-int E; // we see this
+int E; // ignored by type-only lookup
using enum E;
-// since-cxx20-error at -1 {{unknown type name E}}
}
#endif
}
diff --git a/clang/test/CXX/drs/cwg28xx.cpp b/clang/test/CXX/drs/cwg28xx.cpp
index da81eccc8dc22..67aa34484fe8b 100644
--- a/clang/test/CXX/drs/cwg28xx.cpp
+++ b/clang/test/CXX/drs/cwg28xx.cpp
@@ -110,22 +110,18 @@ struct A {
} // namespace cwg2858
-namespace cwg2877 { // cwg2877: no tentatively ready 2024-05-31
+namespace cwg2877 { // cwg2877: 19 tentatively ready 2024-05-31
#if __cplusplus >= 202002L
enum E { x };
void f() {
int E;
- // FIXME: OK, names ::E
- using enum E;
- // since-cxx20-error at -1 {{unknown type name E}}
+ using enum E; // OK, names ::E
}
using F = E;
using enum F; // OK, designates ::E
template<class T> using EE = T;
void g() {
- // FIXME: OK, designates ::E
- using enum EE<E>;
- // since-cxx20-error at -1 {{using enum requires an enum or typedef name}}
+ using enum EE<E>; // OK, designates ::E
}
#endif
} // namespace cwg2877
diff --git a/clang/test/SemaCXX/cxx20-using-enum.cpp b/clang/test/SemaCXX/cxx20-using-enum.cpp
index d16df4e1b9d3c..14ef4b29925a1 100644
--- a/clang/test/SemaCXX/cxx20-using-enum.cpp
+++ b/clang/test/SemaCXX/cxx20-using-enum.cpp
@@ -148,13 +148,10 @@ template <int I> struct C {
enum class D { d,
e,
f };
- using enum D;
-
- static constexpr int W = int(f) + I;
+ using enum D; // expected-error {{using-enum cannot name a dependent type}}
};
static_assert(C<2>::V == 4);
-static_assert(C<20>::W == 22);
} // namespace Seven
@@ -241,6 +238,13 @@ TPLa<int> a;
} // namespace Thirteen
+namespace Fourteen {
+template<typename T>
+int A = T();
+
+using enum A<int>; // expected-error {{A is not an enumerated type}}
+} // namespace Fourteen
+
namespace GH58057 {
struct Wrap {
enum Things {
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 5e2ab06701703..31f5dbde05908 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -15534,7 +15534,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/2621.html">2621</a></td>
<td>C++23</td>
<td>Kind of lookup for <TT>using enum</TT> declarations</td>
- <td class="full" align="center">Clang 16</td>
+ <td title="Clang 19 implements 2024-05-31 resolution" align="center">Superseded by <a href="#2877">2877</a></td>
</tr>
<tr id="2622">
<td><a href="https://cplusplus.github.io/CWG/issues/2622.html">2622</a></td>
@@ -17071,7 +17071,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/2877.html">2877</a></td>
<td>tentatively ready</td>
<td>Type-only lookup for <I>using-enum-declarator</I></td>
- <td title="Clang does not implement 2024-05-31 resolution" align="center">Not Resolved*</td>
+ <td title="Clang 19 implements 2024-05-31 resolution" align="center">Not Resolved*</td>
</tr>
<tr class="open" id="2878">
<td><a href="https://cplusplus.github.io/CWG/issues/2878.html">2878</a></td>
@@ -17198,6 +17198,12 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td>open</td>
<td>Clarify implicit conversion sequence from <I>cv</I> <TT>T</TT> to <TT>T</TT></td>
<td align="center">Not resolved</td>
+ </tr>
+ <tr class="open" id="2899">
+ <td><a href="https://cplusplus.github.io/CWG/issues/2899.html">2899</a></td>
+ <td>open</td>
+ <td>Bad value representations should cause undefined behavior</td>
+ <td align="center">Not resolved</td>
</tr></table>
</div>
>From 40ad6801cd84cfc5a20abfaedc8e122f99891cac Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 13 Jun 2024 14:50:13 +0300
Subject: [PATCH 2/5] Run clang-format
---
clang/include/clang/Sema/Sema.h | 4 ++--
clang/lib/Parse/ParseDeclCXX.cpp | 25 ++++++++++++-------------
clang/lib/Sema/SemaDeclCXX.cpp | 6 +++---
3 files changed, 17 insertions(+), 18 deletions(-)
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index ccabd4925b8a3..dc059f781dcb2 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -4031,8 +4031,8 @@ class Sema final : public SemaBase {
const ParsedAttributesView &AttrList);
Decl *ActOnUsingEnumDeclaration(Scope *CurScope, AccessSpecifier AS,
SourceLocation UsingLoc,
- SourceLocation EnumLoc,
- SourceRange TyLoc, const IdentifierInfo &II, ParsedType Ty,
+ SourceLocation EnumLoc, SourceRange TyLoc,
+ const IdentifierInfo &II, ParsedType Ty,
CXXScopeSpec *SS = nullptr);
Decl *ActOnAliasDeclaration(Scope *CurScope, AccessSpecifier AS,
MultiTemplateParamsArg TemplateParams,
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 189fcc5440292..51e065a6c6a86 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -744,15 +744,15 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
IdentifierInfo *IdentInfo = Tok.getIdentifierInfo();
SourceLocation IdentLoc = ConsumeToken();
- ParsedType Type = Actions.getTypeName(*IdentInfo, IdentLoc, getCurScope(), &SS, /*isClassName=*/true,
- /*HasTrailingDot=*/false,
- /*ObjectType=*/nullptr, /*IsCtorOrDtorName=*/false,
- /*WantNontrivialTypeSourceInfo=*/true);
+ ParsedType Type = Actions.getTypeName(
+ *IdentInfo, IdentLoc, getCurScope(), &SS, /*isClassName=*/true,
+ /*HasTrailingDot=*/false,
+ /*ObjectType=*/nullptr, /*IsCtorOrDtorName=*/false,
+ /*WantNontrivialTypeSourceInfo=*/true);
UED = Actions.ActOnUsingEnumDeclaration(
getCurScope(), AS, UsingLoc, UELoc, IdentLoc, *IdentInfo, Type, &SS);
- }
- else if (Tok.is(tok::annot_template_id)) {
+ } else if (Tok.is(tok::annot_template_id)) {
TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
if (TemplateId->mightBeType()) {
@@ -764,22 +764,21 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
SourceRange Loc = Tok.getAnnotationRange();
ConsumeAnnotationToken();
- UED = Actions.ActOnUsingEnumDeclaration(
- getCurScope(), AS, UsingLoc, UELoc, Loc, *TemplateId->Name, Type.get(), &SS);
- }
- else {
+ UED = Actions.ActOnUsingEnumDeclaration(getCurScope(), AS, UsingLoc,
+ UELoc, Loc, *TemplateId->Name,
+ Type.get(), &SS);
+ } else {
Diag(Tok.getLocation(), diag::err_using_enum_not_enum)
<< TemplateId->Name->getName()
<< SourceRange(TemplateId->TemplateNameLoc, TemplateId->RAngleLoc);
}
- }
- else {
+ } else {
Diag(Tok.getLocation(), diag::err_using_enum_expect_identifier)
<< Tok.is(tok::kw_enum);
SkipUntil(tok::semi);
return nullptr;
}
-
+
if (!UED) {
SkipUntil(tok::semi);
return nullptr;
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index fb9e38d6b5bc9..d65c7df585bac 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -12394,9 +12394,9 @@ Decl *Sema::ActOnUsingDeclaration(Scope *S, AccessSpecifier AS,
Decl *Sema::ActOnUsingEnumDeclaration(Scope *S, AccessSpecifier AS,
SourceLocation UsingLoc,
- SourceLocation EnumLoc,
- SourceRange TyLoc, const IdentifierInfo &II,
- ParsedType Ty, CXXScopeSpec *SS) {
+ SourceLocation EnumLoc, SourceRange TyLoc,
+ const IdentifierInfo &II, ParsedType Ty,
+ CXXScopeSpec *SS) {
assert(!SS->isInvalid() && "ScopeSpec is invalid");
TypeSourceInfo *TSI = nullptr;
SourceLocation IdentLoc = TyLoc.getBegin();
>From d6868d3de4f70fe3cca7ba8409e8cbfeedae1b1a Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 13 Jun 2024 15:02:57 +0300
Subject: [PATCH 3/5] Add a release notes entry
---
clang/docs/ReleaseNotes.rst | 3 +++
1 file changed, 3 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8c2f737836a9d..3ac1029632ffe 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -257,6 +257,9 @@ Resolutions to C++ Defect Reports
- P0522 implementation is enabled by default in all language versions, and
provisional wording for CWG2398 is implemented.
+- Clang now performs type-only lookup for the name in ``using enum`` declaration.
+ (`CWG2877: Type-only lookup for using-enum-declarator <https://cplusplus.github.io/CWG/issues/2877.html>`_).
+
- Clang now requires a template argument list after a template keyword.
(`CWG96: Syntactic disambiguation using the template keyword <https://cplusplus.github.io/CWG/issues/96.html>`_).
>From c19bc288688c73571625aafbd7f0936c1f4ee378 Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 20 Jun 2024 00:01:10 +0300
Subject: [PATCH 4/5] Add fixmes that similarities between `using enum` and
base specifier code should be factored out
---
clang/lib/Parse/ParseDeclCXX.cpp | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 51e065a6c6a86..08c0d5aaaff5e 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -740,6 +740,8 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
Decl *UED = nullptr;
+ // FIXME: identifier and annot_template_id handling is very similar to
+ // ParseBaseTypeSpecifier. It should be factored out into a function.
if (Tok.is(tok::identifier)) {
IdentifierInfo *IdentInfo = Tok.getIdentifierInfo();
SourceLocation IdentLoc = ConsumeToken();
@@ -1434,6 +1436,8 @@ TypeResult Parser::ParseBaseTypeSpecifier(SourceLocation &BaseLoc,
}
// Check whether we have a template-id that names a type.
+ // FIXME: identifier and annot_template_id handling in ParseUsingDeclaration
+ // work very similarly. It should be refactored into a separate function.
if (Tok.is(tok::annot_template_id)) {
TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
if (TemplateId->mightBeType()) {
>From 2cc8a6640b43cd929f6b57cd5417788109039615 Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 20 Jun 2024 15:38:31 +0300
Subject: [PATCH 5/5] Pass `/*IsTypename*/=true` to
`ParseOptionalCXXScopeSpecifier` that handles `using enum`
---
clang/lib/Parse/ParseDeclCXX.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 08c0d5aaaff5e..a28baa1b659a8 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -724,7 +724,7 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
/*ObectHasErrors=*/false,
/*EnteringConttext=*/false,
/*MayBePseudoDestructor=*/nullptr,
- /*IsTypename=*/false,
+ /*IsTypename=*/true,
/*IdentifierInfo=*/nullptr,
/*OnlyNamespace=*/false,
/*InUsingDeclaration=*/true)) {
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