https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107261
--- Comment #1 from Zdenek Sojka <zsojka at seznam dot cz> --- Another testcase, for C code: $ cat testcase.c __bf16 __attribute__((__vector_size__(8))) foo(void) {} $ x86_64-pc-linux-gnu-gcc testcase.c testcase.c: In function 'foo': testcase.c:1:1: internal compiler error: in classify_argument, at config/i386/i386.cc:2523 1 | __bf16 __attribute__((__vector_size__(8))) foo(void) {} | ^~~~~~ 0x8437a7 classify_argument /repo/gcc-trunk/gcc/config/i386/i386.cc:2523 0x1788e56 classify_argument /repo/gcc-trunk/gcc/config/i386/i386.cc:2543 0x1788f28 examine_argument /repo/gcc-trunk/gcc/config/i386/i386.cc:2580 0x17898af ix86_return_in_memory /repo/gcc-trunk/gcc/config/i386/i386.cc:4265 0x1044e71 aggregate_value_p(tree_node const*, tree_node const*) /repo/gcc-trunk/gcc/function.cc:2119 0x1049981 allocate_struct_function(tree_node*, bool) /repo/gcc-trunk/gcc/function.cc:4848 0xd596a4 store_parm_decls() /repo/gcc-trunk/gcc/c/c-decl.cc:10434 0xdbdced c_parser_declaration_or_fndef /repo/gcc-trunk/gcc/c/c-parser.cc:2612 0xdc5eb3 c_parser_external_declaration /repo/gcc-trunk/gcc/c/c-parser.cc:1833 0xdc68d3 c_parser_translation_unit /repo/gcc-trunk/gcc/c/c-parser.cc:1695 0xdc68d3 c_parse_file() /repo/gcc-trunk/gcc/c/c-parser.cc:24213 0xe28a61 c_common_parse_file() /repo/gcc-trunk/gcc/c-family/c-opts.cc:1247 Please submit a full bug report, with preprocessed source (by using -freport-bug). Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions.