c, c++: Use c*_build_qualified_type instead of build_qualified_type from within build_type_attribute_qual_variant [PR101312]

The following testcases ICE in various ways because of the interaction
between attributes and C/C++ c*_build_qualified_type behavior on array
types and how they affect TYPE_CANONICAL.
For array types, C/C++ moves qualifiers to the element type, but
when a cv qualified array build that way has an attribute applied to it,
we call build_type_attribute_qual_variant and that doesn't have that
handling and builds non-qualified version of the array type with qualified
element type and puts it as TYPE_CANONICAL of the type with attribute
which is a distinct type copy.

The following patch adds a langhook, so that even
build_type_attribute_qual_variant uses for C/C++ for array types
c*_build_qualified_type.
There has been already a related langhook
lang_hooks.types.copy_lang_qualifiers used solely for C++, so instead
of adding another langhook this adds a combined langhook for those two,
where C can handle array types specially and otherwise build_qualified_type,
while C++ ditto + do the function/method type modifiers propagation as
well.

Unfortunately there is a terrible array_as_string hack used by some
of the middle-end warnings which creates some array type with sometimes
an artificial attribute and then has hacks in the c-family type printing
to tweak the printed form, and this hack relies on the previous behavior
of build_type_attribute_qual_variant where it even for C/C++ kept
element type quals unmodified and added normally invalid quals on the
array type itself.  The patch stops using build_type_attribute_qual_variant
for that and instead uses copy_node on the type and adjusts the quals and
adds the attribute to the copy and then ggc_frees it.  Also it renames the
attribute from "array" to "array " to make it clear it is internal
attribute users can't specify even in vendor attributes.

2026-01-28  Jakub Jelinek  <jakub@redhat.com>

	PR c/101312
gcc/
	* langhooks.h (struct lang_hooks_for_types): Remove
	copy_lang_qualifiers.  Add build_lang_qualified_type.
	* langhooks.cc (lhd_build_lang_qualified_type): New function.
	* langhooks-def.h (lhd_build_lang_qualified_type): Declare.
	(LANG_HOOKS_COPY_LANG_QUALIFIERS): Remove.
	(LANG_HOOKS_BUILD_LANG_QUALIFIED_TYPE): Add.
	(LANG_HOOKS_FOR_TYPES_INITIALIZER): Use
	LANG_HOOKS_BUILD_LANG_QUALIFIED_TYPE instead of
	LANG_HOOKS_COPY_LANG_QUALIFIERS.
	* attribs.cc (build_type_attribute_qual_variant): Use
	lang_hooks.types.build_lang_qualified_type instead of
	build_qualified_type and/or build_qualified_type with
	optional lang_hooks.types.copy_lang_qualifiers call.
	(attr_access::array_as_string): Use "array " attribute instead of
	"array".  If attribute has been created or intended quals differ
	from quals of build_array_type, use copy_node and adjust quals and
	attributes on the copy, print and then ggc_free.
gcc/c-family/
	* c-pretty-print.cc (c_pretty_printer::direct_abstract_declarator):
	Look up "array " attribute instead of "array".
gcc/c/
	* c-tree.h (c_build_lang_qualified_type): Declare.
	* c-objc-common.h (LANG_HOOKS_BUILD_LANG_QUALIFIED_TYPE): Define.
	* c-objc-common.cc (c_build_lang_qualified_type): New function.
gcc/cp/
	* cp-tree.h (cxx_build_lang_qualified_type): Declare.
	* cp-objcp-common.h (LANG_HOOKS_COPY_LANG_QUALIFIERS): Remove.
	(LANG_HOOKS_BUILD_LANG_QUALIFIED_TYPE): Define.
	* tree.cc (cxx_build_lang_qualified_type): New function.
gcc/testsuite/
	* c-c++-common/pr101312-1.c: New test.
	* c-c++-common/pr101312-2.c: New test.

0 files changed, 0 insertions, 0 deletions