jyknight created this revision.
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Const class members may be initialized with a defaulted default
constructor under the same conditions it would be allowed for a const
object elsewhere.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D126170
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/CXX/drs/dr23xx.cpp
clang/test/CXX/special/class.ctor/p5-0x.cpp
clang/test/SemaCXX/cxx0x-deleted-default-ctor.cpp
clang/www/cxx_dr_status.html
Index: clang/www/cxx_dr_status.html
===================================================================
--- clang/www/cxx_dr_status.html
+++ clang/www/cxx_dr_status.html
@@ -14178,7 +14178,7 @@
<td><a href="https://wg21.link/cwg2394";>2394</a></td>
<td>CD5</td>
<td>Const-default-constructible for members</td>
- <td class="none" align="center">Unknown</td>
+ <td class="unreleased" align="center">Clang 15</td>
</tr>
<tr class="open" id="2395">
<td><a href="https://wg21.link/cwg2395";>2395</a></td>
Index: clang/test/SemaCXX/cxx0x-deleted-default-ctor.cpp
===================================================================
--- clang/test/SemaCXX/cxx0x-deleted-default-ctor.cpp
+++ clang/test/SemaCXX/cxx0x-deleted-default-ctor.cpp
@@ -48,8 +48,12 @@
};
good g;
+struct bad_const_inner {
+ int x;
+};
+
struct bad_const {
- const good g; // expected-note {{field 'g' of const-qualified type 'const good' would not be initialized}}
+ const bad_const_inner g; // expected-note {{field 'g' of const-qualified type 'const bad_const_inner' would not be initialized}}
};
bad_const bc; // expected-error {{call to implicitly-deleted default constructor}}
Index: clang/test/CXX/special/class.ctor/p5-0x.cpp
===================================================================
--- clang/test/CXX/special/class.ctor/p5-0x.cpp
+++ clang/test/CXX/special/class.ctor/p5-0x.cpp
@@ -2,6 +2,8 @@
struct DefaultedDefCtor1 {};
struct DefaultedDefCtor2 { DefaultedDefCtor2() = default; };
+struct DefaultedDefCtorUninitialized1 { int x; };
+struct DefaultedDefCtorUninitialized2 { int x; DefaultedDefCtorUninitialized2() = default; };
struct DeletedDefCtor { DeletedDefCtor() = delete; DeletedDefCtor(int); }; // expected-note {{explicitly marked deleted here}}
class PrivateDefCtor { PrivateDefCtor() = default; public: PrivateDefCtor(int); };
struct DeletedDtor { ~DeletedDtor() = delete; }; // expected-note 4{{explicitly marked deleted here}}
@@ -51,21 +53,20 @@
NotDeleted2d nd2d; // expected-note {{first required here}}
// - any non-variant non-static data member of const qualified type (or array
-// thereof) with no brace-or-equal-initializer does not have a user-provided
-// default constructor,
+// thereof) with no brace-or-equal-initializer is not const-default-constructible
class Deleted3a { const int a; }; // expected-note {{because field 'a' of const-qualified type 'const int' would not be initialized}} \
expected-warning {{does not declare any constructor}} \
expected-note {{will never be initialized}}
Deleted3a d3a; // expected-error {{implicitly-deleted default constructor}}
-class Deleted3b { const DefaultedDefCtor1 a[42]; }; // expected-note {{because field 'a' of const-qualified type 'const DefaultedDefCtor1[42]' would not be initialized}}
+class Deleted3b { const DefaultedDefCtorUninitialized1 a[42]; }; // expected-note {{because field 'a' of const-qualified type 'const DefaultedDefCtorUninitialized1[42]' would not be initialized}}
Deleted3b d3b; // expected-error {{implicitly-deleted default constructor}}
-class Deleted3c { const DefaultedDefCtor2 a; }; // expected-note {{because field 'a' of const-qualified type 'const DefaultedDefCtor2' would not be initialized}}
+class Deleted3c { const DefaultedDefCtorUninitialized2 a; }; // expected-note {{because field 'a' of const-qualified type 'const DefaultedDefCtorUninitialized2' would not be initialized}}
Deleted3c d3c; // expected-error {{implicitly-deleted default constructor}}
class NotDeleted3a { const int a = 0; };
NotDeleted3a nd3a;
-class NotDeleted3b { const DefaultedDefCtor1 a[42] = {}; };
+class NotDeleted3b { const DefaultedDefCtorUninitialized1 a[42] = {}; };
NotDeleted3b nd3b;
-class NotDeleted3c { const DefaultedDefCtor2 a = DefaultedDefCtor2(); };
+class NotDeleted3c { const DefaultedDefCtorUninitialized2 a = DefaultedDefCtorUninitialized2(); };
NotDeleted3c nd3c;
union NotDeleted3d { const int a; int b; };
NotDeleted3d nd3d;
@@ -75,6 +76,10 @@
NotDeleted3f nd3f;
struct NotDeleted3g { union { const int a; int b; }; };
NotDeleted3g nd3g;
+struct NotDeleted3h { const DefaultedDefCtor1 a[42]; };
+NotDeleted3h nd3h;
+struct NotDeleted3i { const DefaultedDefCtor2 a; };
+NotDeleted3i nd3i;
// - X is a union and all of its variant members are of const-qualified type (or
// array thereof),
Index: clang/test/CXX/drs/dr23xx.cpp
===================================================================
--- clang/test/CXX/drs/dr23xx.cpp
+++ clang/test/CXX/drs/dr23xx.cpp
@@ -158,3 +158,14 @@
}
} //namespace dr2303
#endif
+
+namespace dr2394 { // dr2394: 15
+
+struct A {};
+const A a;
+
+// Now allowed to default-init B.
+struct B { const A a; };
+B b;
+
+}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -9213,13 +9213,12 @@
<< !!ICI << MD->getParent() << FD << FieldType << /*Reference*/0;
return true;
}
- // C++11 [class.ctor]p5: any non-variant non-static data member of
- // const-qualified type (or array thereof) with no
- // brace-or-equal-initializer does not have a user-provided default
- // constructor.
+ // C++11 [class.ctor]p5 (modified by DR2394): any non-variant non-static
+ // data member of const-qualified type (or array thereof) with no
+ // brace-or-equal-initializer is not const-default-constructible.
if (!inUnion() && FieldType.isConstQualified() &&
!FD->hasInClassInitializer() &&
- (!FieldRecord || !FieldRecord->hasUserProvidedDefaultConstructor())) {
+ (!FieldRecord || !FieldRecord->allowConstDefaultInit())) {
if (Diagnose)
S.Diag(FD->getLocation(), diag::note_deleted_default_ctor_uninit_field)
<< !!ICI << MD->getParent() << FD << FD->getType() << /*Const*/1;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -152,6 +152,9 @@
- Clang shouldn't lookup allocation function in global scope for coroutines
in case it found the allocation function name in the promise_type body.
This fixes Issue `Issue 54881 <https://github.com/llvm/llvm-project/issues/54881>`_.
+- Fix `CWG 2394 <https://wg21.link/cwg2394>`_: Const class members may
+ be initialized with a defaulted default constructor under the same
+ conditions it would be allowed for a const object elsewhere.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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