On 12/12/25 10:39 PM, Patrick Palka wrote:
These patches were prerequisites for another approach to fix PR122752,
bugbut they seem worthwhile bug fixes on their own.
-- >8 --
Since TYPE_POLYMORPHIC_P shares the same storage as other flags for
TYPENAME_TYPE and DECLTYPE_TYPE, we should avoid accidentally using
this accessor on those tree codes. This patch restricts the accessor
to RECORD/UNION_TYPE which allows callers to conveniently guard any
uses with CLASS_TYPE_P. Otherwise with the next patch applied that
rearranges TYPENAME_TYPE flags, noexcept_override_late_checks would
not skip over a TYPENAME_TYPE base leading to an eventual ICE.
OK.
gcc/cp/ChangeLog:
* cp-tree.h (CLASSTYPE_LAMBDA_EXPR): Check CLASS_TYPE_P before
inspecting TYPE_POLYMORPHIC_P.
(TYPE_POLYMORPHIC_P): Restrict to RECORD_TYPE or UNION_TYPE.
Document its use of TREE_LANG_FLAG_2.
* parser.cc (noexcept_override_late_checks): Only
check TYPE_POLYMORPHIC_P on CLASS_TYPE_P types.
* rtti.cc (build_headof): Likewise.
(get_tinfo_ptr_dynamic): Likewise.
(build_typeid): Likewise.
---
gcc/cp/cp-tree.h | 6 ++++--
gcc/cp/parser.cc | 2 +-
gcc/cp/rtti.cc | 9 ++++++---
3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 180c0cad5933..6f244a8bdfd4 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -481,6 +481,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (in VAR_DECL)
STATEMENT_LIST_TRY_BLOCK (in STATEMENT_LIST)
TYPENAME_IS_RESOLVING_P (in TYPENAME_TYPE)
+ TYPE_POLYMORPHIC_P (in RECORD_TYPE and UNION_TYPE)
TARGET_EXPR_DIRECT_INIT_P (in TARGET_EXPR)
FNDECL_USED_AUTO (in FUNCTION_DECL)
DECLTYPE_FOR_LAMBDA_PROXY (in DECLTYPE_TYPE)
@@ -2815,7 +2816,7 @@ struct GTY(()) lang_type {
/* The associated LAMBDA_EXPR that made this class. */
#define CLASSTYPE_LAMBDA_EXPR(NODE) \
- (TYPE_POLYMORPHIC_P (NODE) \
+ (CLASS_TYPE_P (NODE) && TYPE_POLYMORPHIC_P (NODE) \
? NULL_TREE \
: LANG_TYPE_CLASS_CHECK (NODE)->key_method)
#define SET_CLASSTYPE_LAMBDA_EXPR(NODE, VALUE) \
@@ -4570,7 +4571,8 @@ get_vec_init_expr (tree t)
A class that declares or inherits a virtual function is called a
polymorphic class. */
-#define TYPE_POLYMORPHIC_P(NODE) (TREE_LANG_FLAG_2 (NODE))
+#define TYPE_POLYMORPHIC_P(NODE) \
+ (TREE_LANG_FLAG_2 (RECORD_OR_UNION_CHECK (NODE)))
/* Nonzero if this class has a virtual function table pointer. */
#define TYPE_CONTAINS_VPTR_P(NODE) \
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 6db992708782..2160e16a099f 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -31060,7 +31060,7 @@ noexcept_override_late_checks (tree fndecl, tree
class_type)
{
tree basetype = BINFO_TYPE (base_binfo);
- if (!TYPE_POLYMORPHIC_P (basetype))
+ if (!CLASS_TYPE_P (basetype) || !TYPE_POLYMORPHIC_P (basetype))
continue;
tree fn = look_for_overrides_here (basetype, fndecl);
diff --git a/gcc/cp/rtti.cc b/gcc/cp/rtti.cc
index c06a18b3ff11..1e787157b7b4 100644
--- a/gcc/cp/rtti.cc
+++ b/gcc/cp/rtti.cc
@@ -166,7 +166,7 @@ build_headof (tree exp)
gcc_assert (TYPE_PTR_P (type));
type = TREE_TYPE (type);
- if (!TYPE_POLYMORPHIC_P (type))
+ if (!CLASS_TYPE_P (type) || !TYPE_POLYMORPHIC_P (type))
return exp;
/* We use this a couple of times below, protect it. */
@@ -280,7 +280,9 @@ get_tinfo_ptr_dynamic (tree exp, tsubst_flags_t complain)
return error_mark_node;
/* If exp is a reference to polymorphic type, get the real type_info. */
- if (TYPE_POLYMORPHIC_P (type) && ! resolves_to_fixed_type_p (exp, 0))
+ if (CLASS_TYPE_P (type)
+ && TYPE_POLYMORPHIC_P (type)
+ && ! resolves_to_fixed_type_p (exp, 0))
{
/* build reference to type_info from vtable. */
tree index;
@@ -353,7 +355,8 @@ build_typeid (tree exp, tsubst_flags_t complain)
if (processing_template_decl)
return build_min (TYPEID_EXPR, const_type_info_type_node, exp);
- if (TYPE_POLYMORPHIC_P (TREE_TYPE (exp))
+ if (CLASS_TYPE_P (TREE_TYPE (exp))
+ && TYPE_POLYMORPHIC_P (TREE_TYPE (exp))
&& ! resolves_to_fixed_type_p (exp, &nonnull)
&& ! nonnull)
{
