Hi!
The testcase shows some accepts-invalid (the ones without alignas) and
ice-on-invalid-code (the ones with alignas) cases.
If the enum doesn't have an underlying type and is not a definition,
the caller retries to parse it as elaborated type specifier.
E.g. for enum struct S s it will then pedwarn that elaborated type specifier
shouldn't have the struct/class keywords.
The problem is if the enum specifier is not followed by { when it has
underlying type. In that case we have already called
cp_parser_parse_definitely to end the tentative parsing started at the
beginning of cp_parser_enum_specifier. But the
cp_parser_error (parser, "expected %<;%> or %<{%>");
doesn't emit any error because the whole function is called from yet another
tentative parse and the caller starts parsing the elaborated type
specifier where the cp_parser_enum_specifier stopped (i.e. after the
underlying type token(s)). The ultimate caller than commits the tentative
parsing (and even if it wouldn't, it wouldn't know what kind of error
to report). I think after seeing enum {,struct,class} : type not being
followed by { or ;, there is no reason not to report it right away, as it
can't be valid C++, which is what the patch does. Not sure if we shouldn't
also return error_mark_node instead of NULL_TREE, so that the caller doesn't
try to parse it as elaborated type specifier (the patch doesn't do that
right now).
Furthermore, while reading the code, I've noticed that
parser->colon_corrects_to_scope_p is saved and set to false at the start
of the function, but not restored back in some cases. Don't have a testcase
where this would be a problem, but it just seems wrong. Either we can in
the two spots replace return NULL_TREE; with { type = NULL_TREE; goto out; }
or we could perhaps abuse warning_sentinel or create a special class with
dtor to clean the flag up.
And lastly, I've fixed some formatting issues in the function while reading
it.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2020-03-14 Jakub Jelinek <ja...@redhat.com>
PR c++/90995
* parser.c (cp_parser_enum_specifier): Make sure to restore
parser->colon_corrects_to_scope_p in all cases. If scoped
enum or enum with underlying type is not followed by { or ;,
call error_at rather than cp_parser_error. Formatting fixes.
* g++.dg/cpp0x/enum40.C: New test.
--- gcc/cp/parser.c.jj 2020-03-12 18:17:58.039230033 +0100
+++ gcc/cp/parser.c 2020-03-13 21:44:20.117085594 +0100
@@ -19043,24 +19043,24 @@ cp_parser_enum_specifier (cp_parser* par
push_deferring_access_checks (dk_no_check);
nested_name_specifier
- = cp_parser_nested_name_specifier_opt (parser,
- /*typename_keyword_p=*/true,
- /*check_dependency_p=*/false,
- /*type_p=*/false,
- /*is_declaration=*/false);
+ = cp_parser_nested_name_specifier_opt (parser,
+ /*typename_keyword_p=*/true,
+ /*check_dependency_p=*/false,
+ /*type_p=*/false,
+ /*is_declaration=*/false);
if (nested_name_specifier)
{
tree name;
identifier = cp_parser_identifier (parser);
- name = cp_parser_lookup_name (parser, identifier,
- enum_type,
- /*is_template=*/false,
- /*is_namespace=*/false,
- /*check_dependency=*/true,
- /*ambiguous_decls=*/NULL,
- input_location);
+ name = cp_parser_lookup_name (parser, identifier,
+ enum_type,
+ /*is_template=*/false,
+ /*is_namespace=*/false,
+ /*check_dependency=*/true,
+ /*ambiguous_decls=*/NULL,
+ input_location);
if (name && name != error_mark_node)
{
type = TREE_TYPE (name);
@@ -19117,7 +19117,10 @@ cp_parser_enum_specifier (cp_parser* par
/* At this point this is surely not elaborated type specifier. */
if (!cp_parser_parse_definitely (parser))
- return NULL_TREE;
+ {
+ type = NULL_TREE;
+ goto out;
+ }
if (cxx_dialect < cxx11)
maybe_warn_cpp0x (CPP0X_SCOPED_ENUMS);
@@ -19151,17 +19154,23 @@ cp_parser_enum_specifier (cp_parser* par
if ((scoped_enum_p || underlying_type)
&& cp_lexer_next_token_is_not (parser->lexer, CPP_SEMICOLON))
{
- cp_parser_error (parser, "expected %<;%> or %<{%>");
if (has_underlying_type)
{
+ error_at (cp_lexer_peek_token (parser->lexer)->location,
+ "expected %<;%> or %<{%>");
type = NULL_TREE;
goto out;
}
+ else
+ cp_parser_error (parser, "expected %<;%> or %<{%>");
}
}
if (!has_underlying_type && !cp_parser_parse_definitely (parser))
- return NULL_TREE;
+ {
+ type = NULL_TREE;
+ goto out;
+ }
if (nested_name_specifier)
{
@@ -19172,9 +19181,7 @@ cp_parser_enum_specifier (cp_parser* par
push_scope (nested_name_specifier);
}
else if (TREE_CODE (nested_name_specifier) == NAMESPACE_DECL)
- {
- push_nested_namespace (nested_name_specifier);
- }
+ push_nested_namespace (nested_name_specifier);
}
/* Issue an error message if type-definitions are forbidden here. */
--- gcc/testsuite/g++.dg/cpp0x/enum40.C.jj 2020-03-13 21:32:17.677763299
+0100
+++ gcc/testsuite/g++.dg/cpp0x/enum40.C 2020-03-13 21:31:51.283153431 +0100
@@ -0,0 +1,26 @@
+// PR c++/90995
+// { dg-do compile { target c++11 } }
+
+void
+foo ()
+{
+ enum : int a alignas; // { dg-error "expected" }
+}
+
+void
+bar ()
+{
+ enum : int a; // { dg-error "expected" }
+}
+
+void
+baz ()
+{
+ enum class a : int b alignas; // { dg-error "expected" }
+}
+
+void
+qux ()
+{
+ enum class a : int b; // { dg-error "expected" }
+}
Jakub
