In r11-2064 I made cp_parser_enum_specifier commit to tentative parse
when seeing a '{'. That still looks like the correct thing to do, but
it caused an ICE-on-invalid as well as accepts-invalid.
When we have something sneaky like this, which is broken in multiple
ways:
template <class>
enum struct c : union enum struct c { e = b, f = a };
we parse the "enum struct c" part (that's OK) and then we see that
we have an enum-base, so we consume ':' and then parse the type-specifier
that follows the :. "union enum" is clearly invalid, but we're still
parsing tentatively and we parse everything up to the ;, and then
throw away the underlying type. We parsed everything because we were
tricked into parsing an enum-specifier in an enum-base of another
enum-specifier! Not good.
Since the grammar for enum-base doesn't allow a defining-type-specifier,
only a type-specifier, we should set type_definition_forbidden_message
which fixes all the problems in this PR.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk (GCC 12)?
This may be too obscure to fix in 11.2, but it looks like a reasonable
change to backport.
gcc/cp/ChangeLog:
PR c++/96380
* parser.c (cp_parser_enum_specifier): Don't allow defining
types in enum-base.
gcc/testsuite/ChangeLog:
PR c++/96380
* g++.dg/cpp0x/enum_base4.C: New test.
* g++.dg/cpp0x/enum_base5.C: New test.
---
gcc/cp/parser.c | 4 ++++
gcc/testsuite/g++.dg/cpp0x/enum_base4.C | 8 ++++++++
gcc/testsuite/g++.dg/cpp0x/enum_base5.C | 7 +++++++
3 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/enum_base4.C
create mode 100644 gcc/testsuite/g++.dg/cpp0x/enum_base5.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 99eccf0c5e4..fba516efa23 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -19942,6 +19942,10 @@ cp_parser_enum_specifier (cp_parser* parser)
/* Consume the `:'. */
cp_lexer_consume_token (parser->lexer);
+ auto tdf
+ = make_temp_override (parser->type_definition_forbidden_message,
+ G_("types may not be defined in enum-base"));
+
/* Parse the type-specifier-seq. */
cp_parser_type_specifier_seq (parser, CP_PARSER_FLAGS_NONE,
/*is_declaration=*/false,
diff --git a/gcc/testsuite/g++.dg/cpp0x/enum_base4.C
b/gcc/testsuite/g++.dg/cpp0x/enum_base4.C
new file mode 100644
index 00000000000..b3015256386
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/enum_base4.C
@@ -0,0 +1,8 @@
+// PR c++/96380
+// { dg-do compile { target c++11 } }
+
+extern const int a, b;
+enum struct c;
+template <class>
+enum struct c : union enum struct c { e = b, f = a }; // { dg-error "types
may not be defined|expected|elaborated-type-specifier" }
+enum class c {};
diff --git a/gcc/testsuite/g++.dg/cpp0x/enum_base5.C
b/gcc/testsuite/g++.dg/cpp0x/enum_base5.C
new file mode 100644
index 00000000000..c01e857e612
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/enum_base5.C
@@ -0,0 +1,7 @@
+// PR c++/96380
+// { dg-do compile { target c++11 } }
+
+extern const int a, b;
+enum struct c;
+template <class>
+enum struct c : union enum struct c { e = b, f = a }; // { dg-error "types may
not be defined|expected|elaborated-type-specifier" }
base-commit: 5491da23088734d516aae220810f253b9922c98c
--
2.30.2
