On 2/5/26 1:53 AM, Marek Polacek wrote:
On Wed, Feb 04, 2026 at 08:06:18PM +0900, Jason Merrill wrote:
On 2/4/26 6:11 AM, Marek Polacek wrote:
Bootstrapped/regtested on ppc64le-pc-linux-gnu, ok for 17.0?
-- >8 --
This implements [class.bit]/2: An unnamed bit-field shall not be
declared with a cv-qualified type. This was clarified in DR 2229.
DR 2229
PR c++/123935
gcc/cp/ChangeLog:
* decl2.cc (grokbitfield): Disallow cv-qualified unnamed bit-fields.
gcc/testsuite/ChangeLog:
* g++.dg/DRs/dr2229.C: New test.
---
gcc/cp/decl2.cc | 9 +++++++++
gcc/testsuite/g++.dg/DRs/dr2229.C | 12 ++++++++++++
2 files changed, 21 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/DRs/dr2229.C
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 20ee662eea2..eb2294fffd0 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -1635,6 +1635,15 @@ grokbitfield (const cp_declarator *declarator,
return NULL_TREE;
}
+ /* [class.bit]/2 "An unnamed bit-field shall not be declared with
+ a cv-qualified type." */
+ if (!DECL_NAME (value) && TYPE_QUALS (type) != TYPE_UNQUALIFIED)
+ {
+ error_at (DECL_SOURCE_LOCATION (value),
This seems like a pedwarn rather than an error.
+ "unnamed bit-field cannot be cv-qualified");
+ return NULL_TREE;
...and then continue.
clang++ gives an error, but any diagnostic will do. Thus:
dg.exp passed on x86_64-pc-linux-gnu.
OK, thanks.
-- >8 --
This implements [class.bit]/2: An unnamed bit-field shall not be
declared with a cv-qualified type. This was clarified in DR 2229.
DR 2229
PR c++/123935
gcc/cp/ChangeLog:
* decl2.cc (grokbitfield): Add pedwarn for cv-qualified unnamed
bit-fields.
gcc/testsuite/ChangeLog:
* g++.dg/DRs/dr2229.C: New test.
---
gcc/cp/decl2.cc | 6 ++++++
gcc/testsuite/g++.dg/DRs/dr2229.C | 23 +++++++++++++++++++++++
2 files changed, 29 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/DRs/dr2229.C
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 20ee662eea2..694c23d851e 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -1635,6 +1635,12 @@ grokbitfield (const cp_declarator *declarator,
return NULL_TREE;
}
+ /* [class.bit]/2 "An unnamed bit-field shall not be declared with
+ a cv-qualified type." */
+ if (!DECL_NAME (value) && TYPE_QUALS (type) != TYPE_UNQUALIFIED)
+ pedwarn (DECL_SOURCE_LOCATION (value), 0,
+ "unnamed bit-field cannot be cv-qualified");
+
int flags = LOOKUP_IMPLICIT;
if (init && DIRECT_LIST_INIT_P (init))
flags = LOOKUP_NORMAL;
diff --git a/gcc/testsuite/g++.dg/DRs/dr2229.C
b/gcc/testsuite/g++.dg/DRs/dr2229.C
new file mode 100644
index 00000000000..a55604bf8a9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/DRs/dr2229.C
@@ -0,0 +1,23 @@
+// DR 2229, Volatile unnamed bit-fields
+// PR c++/123935
+
+typedef const unsigned cu;
+typedef volatile unsigned vu;
+typedef const volatile unsigned cvu;
+
+struct S {
+ const unsigned : 1; // { dg-error "unnamed bit-field cannot be cv-qualified"
}
+ volatile unsigned : 1; // { dg-error "unnamed bit-field cannot be
cv-qualified" }
+ const volatile unsigned : 1; // { dg-error "unnamed bit-field cannot be
cv-qualified" }
+ unsigned : 1;
+ const unsigned i1 : 1;
+ volatile unsigned i2 : 1;
+ const volatile unsigned i3 : 1;
+
+ cu : 1; // { dg-error "unnamed bit-field cannot be cv-qualified" }
+ vu : 1; // { dg-error "unnamed bit-field cannot be cv-qualified" }
+ cvu : 1; // { dg-error "unnamed bit-field cannot be cv-qualified" }
+ cu i4: 1;
+ vu i5 : 1;
+ cvu i6 : 1;
+};
base-commit: f6838e731633d8b5b11f15ce3e227e18df2fe46e
