rsmith updated this revision to Diff 243022.
rsmith marked 4 inline comments as done.
rsmith added a comment.
Updates based on review comments from @rjmccall.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D74103/new/
https://reviews.llvm.org/D74103
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/test/Analysis/inlining/eager-reclamation-path-notes.cpp
clang/test/Analysis/padding_cpp.cpp
clang/test/Analysis/padding_message.cpp
clang/test/CXX/class/class.local/p4.cpp
clang/test/CXX/class/class.union/p2-0x.cpp
clang/test/CXX/drs/dr4xx.cpp
clang/test/Modules/submodules-merge-defs.cpp
clang/test/OpenMP/target_map_codegen.cpp
clang/test/SemaCXX/anonymous-struct.cpp
clang/test/SemaCXX/linkage.cpp
clang/test/SemaCXX/linkage2.cpp
clang/test/SemaCXX/undefined-internal.cpp
clang/test/SemaCXX/warn-unused-filescoped.cpp
clang/test/SemaCXX/warn-unused-local-typedef.cpp
clang/test/SemaTemplate/instantiate-function-2.cpp
clang/www/cxx_status.html
Index: clang/www/cxx_status.html
===================================================================
--- clang/www/cxx_status.html
+++ clang/www/cxx_status.html
@@ -1091,7 +1091,7 @@
</tr>
<tr> <!-- from Cologne -->
<td><a href="https://wg21.link/p1766r1";>P1766R1</a> (<a href="#dr">DR</a>)</td>
- <td rowspan="3" class="none" align="center">No</td>
+ <td rowspan="3" class="unreleased" align="center">Clang 11</td>
</tr>
<tr>
<td><a href="https://wg21.link/p1811r0";>P1811R0</a></td>
Index: clang/test/SemaTemplate/instantiate-function-2.cpp
===================================================================
--- clang/test/SemaTemplate/instantiate-function-2.cpp
+++ clang/test/SemaTemplate/instantiate-function-2.cpp
@@ -49,11 +49,11 @@
namespace AliasTagDef {
template<typename T>
T f() {
- using S = struct {
+ using S = struct { // expected-warning {{add a tag name}} expected-note {{}}
#if __cplusplus <= 199711L
// expected-warning@-2 {{alias declarations are a C++11 extension}}
#endif
- T g() {
+ T g() { // expected-note {{}}
return T();
}
};
Index: clang/test/SemaCXX/warn-unused-local-typedef.cpp
===================================================================
--- clang/test/SemaCXX/warn-unused-local-typedef.cpp
+++ clang/test/SemaCXX/warn-unused-local-typedef.cpp
@@ -108,13 +108,13 @@
}
void typedef_in_nested_name() {
- typedef struct {
- typedef int Foo;
- } A;
+ typedef struct { // expected-warning {{add a tag name}}
+ typedef int Foo; // expected-note {{}}
+ } A; // expected-note {{}}
A::Foo adsf;
- using A2 = struct {
- typedef int Foo;
+ using A2 = struct { // expected-warning {{add a tag name}} expected-note {{this alias declaration}}
+ typedef int Foo; // expected-note {{}}
};
A2::Foo adsf2;
}
Index: clang/test/SemaCXX/warn-unused-filescoped.cpp
===================================================================
--- clang/test/SemaCXX/warn-unused-filescoped.cpp
+++ clang/test/SemaCXX/warn-unused-filescoped.cpp
@@ -164,9 +164,9 @@
}
namespace test6 {
- typedef struct {
- void bar();
- } A;
+ typedef struct { // expected-warning {{add a tag name}}
+ void bar(); // expected-note {{}}
+ } A; // expected-note {{}}
typedef struct {
void bar(); // expected-warning {{unused member function 'bar'}}
Index: clang/test/SemaCXX/undefined-internal.cpp
===================================================================
--- clang/test/SemaCXX/undefined-internal.cpp
+++ clang/test/SemaCXX/undefined-internal.cpp
@@ -206,12 +206,12 @@
}
namespace test7 {
- typedef struct {
- void bar();
+ typedef struct { // expected-warning {{add a tag name}}
+ void bar(); // expected-note {{this member}}
void foo() {
bar();
}
- } A;
+ } A; // expected-note {{this typedef}}
}
namespace test8 {
Index: clang/test/SemaCXX/linkage2.cpp
===================================================================
--- clang/test/SemaCXX/linkage2.cpp
+++ clang/test/SemaCXX/linkage2.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -std=gnu++11 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -Wno-c++11-extensions -Wno-local-type-template-args %s -std=gnu++98
-// RUN: %clang_cc1 -fsyntax-only -verify -Wno-c++11-extensions -Wno-local-type-template-args -fmodules %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-non-c-typedef-for-linkage -std=gnu++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-non-c-typedef-for-linkage -Wno-c++11-extensions -Wno-local-type-template-args %s -std=gnu++98
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-non-c-typedef-for-linkage -Wno-c++11-extensions -Wno-local-type-template-args -fmodules %s
namespace test1 {
int x; // expected-note {{previous definition is here}}
@@ -245,7 +245,8 @@
void f() { struct Inner {}; Use<Inner> ui; }
} F;
#if __cplusplus < 201103L
- // expected-error@-2 {{unsupported: typedef changes linkage of anonymous type, but linkage was already computed}}
- // expected-note@-5 {{use a tag name here}}
+ // expected-error@-4 {{given name for linkage purposes by typedef declaration after its linkage was computed}}
+ // expected-note@-4 {{due to this member}}
+ // expected-note@-4 {{by this typedef}}
#endif
}
Index: clang/test/SemaCXX/linkage.cpp
===================================================================
--- clang/test/SemaCXX/linkage.cpp
+++ clang/test/SemaCXX/linkage.cpp
@@ -3,7 +3,7 @@
// compared against the earlier cached value. If we had a way of
// testing linkage directly in Sema, that would be better.
-// RUN: %clang_cc1 -Werror -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -Werror -Wno-non-c-typedef-for-linkage -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s
// CHECK: @_ZZN5test61A3fooEvE3bar = linkonce_odr global i32 0, align 4
Index: clang/test/SemaCXX/anonymous-struct.cpp
===================================================================
--- clang/test/SemaCXX/anonymous-struct.cpp
+++ clang/test/SemaCXX/anonymous-struct.cpp
@@ -1,6 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s
struct S {
S();
@@ -27,15 +28,69 @@
};
template <class T> void foo(T);
-typedef struct { // expected-note {{use a tag name here to establish linkage prior to definition}}
+typedef struct { // expected-error {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration after its linkage was computed; add a tag name here to establish linkage prior to definition}}
#if __cplusplus <= 199711L
// expected-note@-2 {{declared here}}
#endif
- void test() {
+ void test() { // expected-note {{type is not C-compatible due to this member declaration}}
foo(this);
#if __cplusplus <= 199711L
// expected-warning@-2 {{template argument uses unnamed type}}
#endif
}
-} A; // expected-error {{unsupported: typedef changes linkage of anonymous type, but linkage was already computed}}
+} A; // expected-note {{type is given name 'A' for linkage purposes by this typedef declaration}}
+
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ int x = 0; // expected-note {{type is not C-compatible due to this default member initializer}} expected-warning 0-1{{extension}}
+} B; // expected-note {{type is given name 'B' for linkage purposes by this typedef declaration}}
+
+typedef struct // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+: B { // expected-note {{type is not C-compatible due to this base class}}
+} C; // expected-note {{type is given name 'C' for linkage purposes by this typedef declaration}}
+
+#if __cplusplus > 201703L
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ static_assert([]{ return true; }()); // expected-note {{type is not C-compatible due to this lambda expression}}
+} Lambda1; // expected-note {{type is given name 'Lambda1' for linkage purposes by this typedef declaration}}
+
+template<int> struct X {};
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ X<[]{ return 0; }()> x; // expected-note {{type is not C-compatible due to this lambda expression}}
+ // FIXME: expected-error@-1 {{lambda expression cannot appear}}
+} Lambda2; // expected-note {{type is given name 'Lambda2' for linkage purposes by this typedef declaration}}
+
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ enum E {
+ a = []{ return 1; }() // expected-note {{type is not C-compatible due to this lambda expression}}
+ };
+} Lambda3; // expected-note {{type is given name 'Lambda3' for linkage purposes by this typedef declaration}}
+#endif
+
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ template<int> void f() {} // expected-note {{type is not C-compatible due to this member declaration}}
+} Template; // expected-note {{type is given name 'Template' for linkage purposes by this typedef declaration}}
+
+typedef struct { // expected-warning {{anonymous non-C-compatible type given name for linkage purposes by typedef declaration; add a tag name here}}
+ struct U {
+ void f(); // expected-note {{type is not C-compatible due to this member declaration}}
+ };
+} Nested; // expected-note {{type is given name 'Nested' for linkage purposes by this typedef declaration}}
+
+// Check that we don't diagnose the permitted cases:
+typedef struct {
+ // (non-members)
+ _Static_assert(true, "");
+ int : 0;
+ /*empty-declaration*/;
+
+ // non-static data members
+ int a;
+ // member enumerations
+ enum E { x, y, z };
+ // member classes
+ struct S {};
+
+ // recursively
+ struct T { int a; };
+} OK;
Index: clang/test/OpenMP/target_map_codegen.cpp
===================================================================
--- clang/test/OpenMP/target_map_codegen.cpp
+++ clang/test/OpenMP/target_map_codegen.cpp
@@ -5165,7 +5165,7 @@
int *ptrBase1;
} Base;
-typedef struct : public Base {
+typedef struct StructWithPtrTag : public Base {
int *ptr;
int *ptr2;
int val;
Index: clang/test/Modules/submodules-merge-defs.cpp
===================================================================
--- clang/test/Modules/submodules-merge-defs.cpp
+++ clang/test/Modules/submodules-merge-defs.cpp
@@ -10,6 +10,8 @@
#include "empty.h"
#ifdef EARLY_INDIRECT_INCLUDE
#include "indirect.h"
+// expected-warning@defs.h:28 3{{anonymous non-C-compatible type}}
+// expected-note@defs.h:28 6{{type is}}
#endif
A pre_a;
Index: clang/test/CXX/drs/dr4xx.cpp
===================================================================
--- clang/test/CXX/drs/dr4xx.cpp
+++ clang/test/CXX/drs/dr4xx.cpp
@@ -82,6 +82,9 @@
typedef struct {
static int n; // expected-error {{static data member 'n' not allowed in anonymous struct}}
} A;
+ typedef union {
+ static int n; // expected-error {{static data member 'n' not allowed in anonymous union}}
+ } B;
}
namespace dr407 { // dr407: 3.8
Index: clang/test/CXX/class/class.union/p2-0x.cpp
===================================================================
--- clang/test/CXX/class/class.union/p2-0x.cpp
+++ clang/test/CXX/class/class.union/p2-0x.cpp
@@ -37,12 +37,12 @@
struct S {
union {
- static const int n; // expected-error {{static members cannot be declared in an anonymous union}}
+ static const int n; // expected-error {{static data member 'n' not allowed in anonymous union}}
int a;
int b;
};
};
static union {
- static const int k; // expected-error {{static members cannot be declared in an anonymous union}}
+ static const int k; // expected-error {{static data member 'k' not allowed in anonymous union}}
int n;
};
Index: clang/test/CXX/class/class.local/p4.cpp
===================================================================
--- clang/test/CXX/class/class.local/p4.cpp
+++ clang/test/CXX/class/class.local/p4.cpp
@@ -2,9 +2,9 @@
void f() {
struct X {
- static int a; // expected-error {{static data member 'a' not allowed in local class 'X'}}
+ static int a; // expected-error {{static data member 'a' not allowed in local struct 'X'}}
int b;
-
+
static void f() { }
};
}
Index: clang/test/Analysis/padding_message.cpp
===================================================================
--- clang/test/Analysis/padding_message.cpp
+++ clang/test/Analysis/padding_message.cpp
@@ -265,13 +265,13 @@
};
// expected-warning@+7{{\
-Excessive padding in 'TypedefSandwich2' (6 padding bytes, where 2 is optimal). \
+Excessive padding in 'struct TypedefSandwich2' (6 padding bytes, where 2 is optimal). \
Optimal fields order: \
t, \
c1, \
c2, \
}}
-typedef struct {
+typedef struct TypedefSandwich2 {
char c1;
// expected-warning@+7{{\
Excessive padding in 'TypedefSandwich2::NestedTypedef' (6 padding bytes, where 2 is optimal). \
Index: clang/test/Analysis/padding_cpp.cpp
===================================================================
--- clang/test/Analysis/padding_cpp.cpp
+++ clang/test/Analysis/padding_cpp.cpp
@@ -165,7 +165,7 @@
TemplateSandwich<void *> t3;
};
-typedef struct { // expected-warning{{Excessive padding in 'TypedefSandwich2'}}
+typedef struct TypedefSandwich2 { // expected-warning{{Excessive padding in 'struct TypedefSandwich2'}}
char c1;
typedef struct { // expected-warning{{Excessive padding in 'TypedefSandwich2::NestedTypedef'}}
char c1;
Index: clang/test/Analysis/inlining/eager-reclamation-path-notes.cpp
===================================================================
--- clang/test/Analysis/inlining/eager-reclamation-path-notes.cpp
+++ clang/test/Analysis/inlining/eager-reclamation-path-notes.cpp
@@ -2,9 +2,9 @@
// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-output=plist-multi-file -analyzer-config graph-trim-interval=5 -analyzer-config suppress-null-return-paths=false %s -o %t.plist
// RUN: %normalize_plist <%t.plist | diff -ub %S/Inputs/expected-plists/eager-reclamation-path-notes.cpp.plist -
-typedef struct {
+struct IntWrapper {
int getValue();
-} IntWrapper;
+};
IntWrapper *getNullWrapper() {
return 0;
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -4346,6 +4346,81 @@
}
}
+namespace {
+enum class NonCLikeKind {
+ None,
+ BaseClass,
+ DefaultMemberInit,
+ Lambda,
+ Friend,
+ OtherMember,
+ Invalid,
+};
+}
+
+/// Determine whether a class is C-like, according to the rules of C++
+/// [dcl.typedef] for anonymous classes with typedef names for linkage.
+static std::pair<NonCLikeKind, SourceRange>
+getNonCLikeKindForAnonymousStruct(const CXXRecordDecl *RD) {
+ if (RD->isInvalidDecl())
+ return {NonCLikeKind::Invalid, {}};
+
+ // C++ [dcl.typedef]p9: [P1766R1]
+ // An unnamed class with a typedef name for linkage purposes shall not
+ //
+ // -- have any base classes
+ if (RD->getNumBases())
+ return {NonCLikeKind::BaseClass,
+ SourceRange(RD->bases_begin()->getBeginLoc(),
+ RD->bases_end()[-1].getEndLoc())};
+ bool Invalid = false;
+ for (Decl *D : RD->decls()) {
+ // Don't complain about things we already diagnosed.
+ if (D->isInvalidDecl()) {
+ Invalid = true;
+ continue;
+ }
+
+ // -- have any [...] default member initializers
+ if (auto *FD = dyn_cast<FieldDecl>(D)) {
+ if (FD->hasInClassInitializer()) {
+ auto *Init = FD->getInClassInitializer();
+ return {NonCLikeKind::DefaultMemberInit,
+ Init ? Init->getSourceRange() : D->getSourceRange()};
+ }
+ continue;
+ }
+
+ // FIXME: We don't allow friend declarations. This violates the wording of
+ // P1766, but not the intent.
+ if (isa<FriendDecl>(D))
+ return {NonCLikeKind::Friend, D->getSourceRange()};
+
+ // -- declare any members other than non-static data members, member
+ // enumerations, or member classes,
+ if (isa<StaticAssertDecl>(D) || isa<IndirectFieldDecl>(D) ||
+ isa<EnumDecl>(D))
+ continue;
+ auto *MemberRD = dyn_cast<CXXRecordDecl>(D);
+ if (!MemberRD)
+ return {NonCLikeKind::OtherMember, D->getSourceRange()};
+
+ // -- contain a lambda-expression,
+ if (MemberRD->isLambda())
+ return {NonCLikeKind::Lambda, MemberRD->getSourceRange()};
+
+ // and all member classes shall also satisfy these requirements
+ // (recursively).
+ if (MemberRD->isThisDeclarationADefinition()) {
+ auto Kind = getNonCLikeKindForAnonymousStruct(MemberRD);
+ if (Kind.first != NonCLikeKind::None)
+ return Kind;
+ }
+ }
+
+ return {Invalid ? NonCLikeKind::Invalid : NonCLikeKind::None, {}};
+}
+
void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
TypedefNameDecl *NewTD) {
if (TagFromDeclSpec->isInvalidDecl())
@@ -4366,27 +4441,40 @@
return;
}
- // If we've already computed linkage for the anonymous tag, then
- // adding a typedef name for the anonymous decl can change that
- // linkage, which might be a serious problem. Diagnose this as
- // unsupported and ignore the typedef name. TODO: we should
- // pursue this as a language defect and establish a formal rule
- // for how to handle it.
- if (TagFromDeclSpec->hasLinkageBeenComputed()) {
- Diag(NewTD->getLocation(), diag::err_typedef_changes_linkage);
+ // C++ [dcl.typedef]p9: [P1766R1, applied as DR]
+ // An unnamed class with a typedef name for linkage purposes shall [be
+ // C-like].
+ if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(TagFromDeclSpec)) {
+ auto Kind = getNonCLikeKindForAnonymousStruct(RD);
+ if (Kind.first == NonCLikeKind::Invalid)
+ return;
+ if (Kind.first != NonCLikeKind::None) {
+ bool Extension = !TagFromDeclSpec->hasLinkageBeenComputed();
- SourceLocation tagLoc = TagFromDeclSpec->getInnerLocStart();
- tagLoc = getLocForEndOfToken(tagLoc);
+ SourceLocation FixitLoc =
+ getLocForEndOfToken(TagFromDeclSpec->getInnerLocStart());
+ llvm::SmallString<40> TextToInsert;
+ TextToInsert += ' ';
+ TextToInsert += NewTD->getIdentifier()->getName();
- llvm::SmallString<40> textToInsert;
- textToInsert += ' ';
- textToInsert += NewTD->getIdentifier()->getName();
- Diag(tagLoc, diag::note_typedef_changes_linkage)
- << FixItHint::CreateInsertion(tagLoc, textToInsert);
- return;
+ Diag(FixitLoc, Extension ? diag::ext_non_c_like_anon_struct_in_typedef
+ : diag::err_non_c_like_anon_struct_in_typedef)
+ << isa<TypeAliasDecl>(NewTD)
+ << FixItHint::CreateInsertion(FixitLoc, TextToInsert);
+ Diag(Kind.second.getBegin(), diag::note_non_c_like_anon_struct)
+ << int(Kind.first) - 1 << Kind.second;
+ Diag(NewTD->getLocation(), diag::note_typedef_for_linkage_here)
+ << NewTD << isa<TypeAliasDecl>(NewTD);
+ if (!Extension)
+ return;
+ }
}
- // Otherwise, set this is the anon-decl typedef for the tag.
+ // If we compute the linkage of a C-compatible type early, that's a bug.
+ assert(!TagFromDeclSpec->hasLinkageBeenComputed() &&
+ "linkage unexpectedly computed for C-compatible anonymous type");
+
+ // Otherwise, set this as the anon-decl typedef for the tag.
TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
}
@@ -4917,6 +5005,10 @@
// define non-static data members. [Note: nested types and
// functions cannot be declared within an anonymous union. ]
for (auto *Mem : Record->decls()) {
+ // Ignore invalid declarations; we already diagnosed them.
+ if (Mem->isInvalidDecl())
+ continue;
+
if (auto *FD = dyn_cast<FieldDecl>(Mem)) {
// C++ [class.union]p3:
// An anonymous union shall not have private or protected
@@ -6757,28 +6849,33 @@
if (SC == SC_Static && CurContext->isRecord()) {
if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC)) {
- if (RD->isLocalClass())
+ // C++ [class.static.data]p2:
+ // A static data member shall not be a direct member of an unnamed
+ // or local class
+ // FIXME: or of a (possibly indirectly) nested class thereof.
+ if (RD->isLocalClass()) {
Diag(D.getIdentifierLoc(),
diag::err_static_data_member_not_allowed_in_local_class)
- << Name << RD->getDeclName();
-
- // C++98 [class.union]p1: If a union contains a static data member,
- // the program is ill-formed. C++11 drops this restriction.
- if (RD->isUnion())
+ << Name << RD->getDeclName() << RD->getTagKind();
+ } else if (!RD->getDeclName()) {
+ Diag(D.getIdentifierLoc(),
+ diag::err_static_data_member_not_allowed_in_anon_struct)
+ << Name << RD->getTagKind();
+ Invalid = true;
+ } else if (RD->isUnion()) {
+ // C++98 [class.union]p1: If a union contains a static data member,
+ // the program is ill-formed. C++11 drops this restriction.
Diag(D.getIdentifierLoc(),
getLangOpts().CPlusPlus11
? diag::warn_cxx98_compat_static_data_member_in_union
: diag::ext_static_data_member_in_union) << Name;
- // We conservatively disallow static data members in anonymous structs.
- else if (!RD->getDeclName())
- Diag(D.getIdentifierLoc(),
- diag::err_static_data_member_not_allowed_in_anon_struct)
- << Name << RD->isUnion();
+ }
}
}
// Match up the template parameter lists with the scope specifier, then
// determine whether we have a template or a template specialization.
+ bool InvalidScope = false;
TemplateParams = MatchTemplateParametersToScopeSpecifier(
D.getDeclSpec().getBeginLoc(), D.getIdentifierLoc(),
D.getCXXScopeSpec(),
@@ -6786,7 +6883,8 @@
? D.getName().TemplateId
: nullptr,
TemplateParamLists,
- /*never a friend*/ false, IsMemberSpecialization, Invalid);
+ /*never a friend*/ false, IsMemberSpecialization, InvalidScope);
+ Invalid |= InvalidScope;
if (TemplateParams) {
if (!TemplateParams->size() &&
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -788,10 +788,23 @@
def ext_typedef_without_a_name : ExtWarn<"typedef requires a name">,
InGroup<MissingDeclarations>;
def err_typedef_not_identifier : Error<"typedef name must be an identifier">;
-def err_typedef_changes_linkage : Error<"unsupported: typedef changes linkage"
- " of anonymous type, but linkage was already computed">;
-def note_typedef_changes_linkage : Note<"use a tag name here to establish "
- "linkage prior to definition">;
+
+def ext_non_c_like_anon_struct_in_typedef : ExtWarn<
+ "anonymous non-C-compatible type given name for linkage purposes "
+ "by %select{typedef|alias}0 declaration; "
+ "add a tag name here">, InGroup<DiagGroup<"non-c-typedef-for-linkage">>;
+def err_non_c_like_anon_struct_in_typedef : Error<
+ "anonymous non-C-compatible type given name for linkage purposes "
+ "by %select{typedef|alias}0 declaration after its linkage was computed; "
+ "add a tag name here to establish linkage prior to definition">;
+def note_non_c_like_anon_struct : Note<
+ "type is not C-compatible due to this "
+ "%select{base class|default member initializer|lambda expression|"
+ "friend declaration|member declaration}0">;
+def note_typedef_for_linkage_here : Note<
+ "type is given name %0 for linkage purposes by this "
+ "%select{typedef|alias}1 declaration">;
+
def err_statically_allocated_object : Error<
"interface type cannot be statically allocated">;
def err_object_cannot_be_passed_returned_by_value : Error<
@@ -1796,8 +1809,13 @@
"because type %0 has a member with %select{no|no|__strong|__weak|"
"__autoreleasing}1 ownership">;
+/// Selector for a TagTypeKind value.
+def select_tag_type_kind : TextSubstitution<
+ "%select{struct|interface|union|class|enum}0">;
+
def err_static_data_member_not_allowed_in_anon_struct : Error<
- "static data member %0 not allowed in anonymous struct">;
+ "static data member %0 not allowed in anonymous "
+ "%sub{select_tag_type_kind}1">;
def ext_static_data_member_in_union : ExtWarn<
"static data member %0 in union is a C++11 extension">, InGroup<CXX11>;
def warn_cxx98_compat_static_data_member_in_union : Warning<
@@ -8114,7 +8132,7 @@
"%select{%3|block literal|lambda expression|context}2">;
def err_static_data_member_not_allowed_in_local_class : Error<
- "static data member %0 not allowed in local class %1">;
+ "static data member %0 not allowed in local %sub{select_tag_type_kind}2 %1">;
// C++ derived classes
def err_base_clause_on_union : Error<"unions cannot have base classes">;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -99,6 +99,43 @@
C++ Language Changes in Clang
-----------------------------
+- Clang now implements a restriction on giving non-C-compatible anonymous
+ structs a typedef name for linkage purposes, as described in C++ committee
+ paper `P1766R1 <http://wg21.link/p1766r1>`. This paper was adopted by the
+ C++ committee as a Defect Report resolution, so it is applied retroactively
+ to all C++ standard versions. This affects code such as:
+
+ .. code-block:: c++
+
+ typedef struct {
+ int f() { return 0; }
+ } S;
+
+ Previous versions of Clang rejected some constructs of this form
+ (specifically, where the linkage of the type happened to be computed
+ before the parser reached the typedef name); those cases are still rejected
+ in Clang 11. In addition, cases that previous versions of Clang did not
+ reject now produce an extension warning. This warning can be disabled with
+ the warning flag ``-Wno-non-c-typedef-for-linkage``.
+
+ Affected code should be updated to provide a tag name for the anonymous
+ struct:
+
+ .. code-block:: c++
+
+ struct S {
+ int f() { return 0; }
+ };
+
+ If the code is shared with a C compilation (for example, if the parts that
+ are not C-compatible are guarded with ``#ifdef __cplusplus``), the typedef
+ declaration should be retained, but a tag name should still be provided:
+
+ .. code-block:: c++
+
+ typedef struct S {
+ int f() { return 0; }
+ } S;
C++1z Feature Support
^^^^^^^^^^^^^^^^^^^^^
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