Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
We were checking for overlap using same_type_p and therefore allocating two
Empty subobjects at the same offset because one was cv-qualified.
This gives the warning at the location of the class name rather than the
member declaration, but this should be a rare enough issue that it doesn't
seem worth trying to be more precise.
gcc/ChangeLog:
* common.opt: Update -fabi-version=19.
gcc/cp/ChangeLog:
* class.cc (check_subobject_offset): Check
same_type_ignoring_top_level_qualifiers_p.
gcc/testsuite/ChangeLog:
* g++.dg/abi/no_unique_address8.C: New test.
* g++.dg/abi/no_unique_address8a.C: New test.
---
gcc/common.opt| 1 +
gcc/cp/class.cc | 28 +++--
gcc/testsuite/g++.dg/abi/no_unique_address8.C | 30 ++
.../g++.dg/abi/no_unique_address8a.C | 31 +++
4 files changed, 88 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/abi/no_unique_address8.C
create mode 100644 gcc/testsuite/g++.dg/abi/no_unique_address8a.C
diff --git a/gcc/common.opt b/gcc/common.opt
index 3e1939293e8..f137a1f81ac 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1011,6 +1011,7 @@ Driver Undocumented
; Default in G++ 13.
;
; 19: Emits ABI tags if needed in structured binding mangled names.
+; Ignores cv-quals on [[no_unique_object]] members.
; Default in G++ 14.
;
; Additional positive integers will be assigned as new versions of
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index 778759237dc..9139a0075ab 100644
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -4053,9 +4053,33 @@ check_subobject_offset (tree type, tree offset,
splay_tree offsets)
if (!n)
return 0;
+ enum { ignore, fast, slow, warn }
+ cv_check = (abi_version_crosses (19) ? slow
+ : abi_version_at_least (19) ? fast
+ : ignore);
for (t = (tree) n->value; t; t = TREE_CHAIN (t))
-if (same_type_p (TREE_VALUE (t), type))
- return 1;
+{
+ tree elt = TREE_VALUE (t);
+
+ if (same_type_p (elt, type))
+ return 1;
+
+ if (cv_check != ignore
+ && same_type_ignoring_top_level_qualifiers_p (elt, type))
+ {
+ if (cv_check == fast)
+ return 1;
+ cv_check = warn;
+ }
+}
+
+ if (cv_check == warn)
+{
+ warning (OPT_Wabi, "layout of %qs member of type %qT changes in %qs",
+ "[[no_unique_address]]", type, "-fabi-version=19");
+ if (abi_version_at_least (19))
+ return 1;
+}
return 0;
}
diff --git a/gcc/testsuite/g++.dg/abi/no_unique_address8.C
b/gcc/testsuite/g++.dg/abi/no_unique_address8.C
new file mode 100644
index 000..6aa2bba7810
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/no_unique_address8.C
@@ -0,0 +1,30 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-fabi-version=19 -Wabi=18" }
+
+#include
+
+#define NOUNIQUE [[no_unique_address]]
+
+struct Empty { };
+#define CHECK_DISTINCT(type, field1, field2) static_assert(offsetof(type,
field1) != offsetof(type, field2))
+
+struct A1 {
+NOUNIQUE Empty a;
+Empty b;
+};
+CHECK_DISTINCT(A1, a, b);
+struct A2 {
+NOUNIQUE const Empty a;
+const Empty b;
+};
+CHECK_DISTINCT(A2, a, b);
+struct A3 {// { dg-warning "layout" }
+NOUNIQUE const Empty a;
+Empty b;
+};
+CHECK_DISTINCT(A3, a, b);
+struct A4 {// { dg-warning "layout" }
+NOUNIQUE Empty a;
+const Empty b;
+};
+CHECK_DISTINCT(A4, a, b);
diff --git a/gcc/testsuite/g++.dg/abi/no_unique_address8a.C
b/gcc/testsuite/g++.dg/abi/no_unique_address8a.C
new file mode 100644
index 000..c5d48088529
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/no_unique_address8a.C
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-fabi-version=18 -Wabi=19" }
+
+#include
+
+#define NOUNIQUE [[no_unique_address]]
+
+struct Empty { };
+#define CHECK_DISTINCT(type, field1, field2) static_assert(offsetof(type,
field1) != offsetof(type, field2))
+#define CHECK_SAME(type, field1, field2) static_assert(offsetof(type, field1)
== offsetof(type, field2))
+
+struct A1 {
+NOUNIQUE Empty a;
+Empty b;
+};
+CHECK_DISTINCT(A1, a, b);
+struct A2 {
+NOUNIQUE const Empty a;
+const Empty b;
+};
+CHECK_DISTINCT(A2, a, b);
+struct A3 {// { dg-warning "layout" }
+NOUNIQUE const Empty a;
+Empty b;
+};
+CHECK_SAME(A3, a, b);
+struct A4 {// { dg-warning "layout" }
+NOUNIQUE Empty a;
+const Empty b;
+};
+CHECK_SAME(A4, a, b);
base-commit: 244d1321340116b7780e78096356f69662fd0e18
--
2.39.3
