[Bug c/122865] New: ICE in c_type_tag, at c/c-typeck.cc (dereference va_list)

[522024330006 at smail dot nju.edu.cn via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122865

            Bug ID: 122865
           Summary: ICE in c_type_tag, at c/c-typeck.cc (dereference
                    va_list)
           Product: gcc
           Version: 15.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 522024330006 at smail dot nju.edu.cn
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/6MKMxzM17

Program:
```c
#include <stdarg.h>
#include <stdio.h>

typedef struct {
    int x;
} X;

typedef struct S {
    int a[10];
    X y;
} *PtrS;


int h(PtrS s, va_list ap) {
    int i = 1;

    for (; i < 5; ++i)
        if (__builtin_types_compatible_p(__typeof__(s->y), __typeof__(*ap)))
            return i;

    return 
}

int main() {
    X u;
    va_list ap;

    h((X*)(&u), ap);

}
```

Part of the traceback:
25618.fuzz:23:9: internal compiler error: in c_type_tag, at c/c-typeck.cc:606
   23 |         if (__builtin_types_compatible_p(__typeof__(s->y),
__typeof__(*ap)))
      |         ^~
0x569ce3c internal_error(char const*, ...)
        /workspace/install/gcc/src/gcc/gcc/diagnostic-global-context.cc:517
0x563a4de fancy_abort(char const*, int, char const*)
        /workspace/install/gcc/src/gcc/gcc/diagnostic.cc:1749
0xe852e6 c_type_tag(tree_node const*)
        /workspace/install/gcc/src/gcc/gcc/c/c-typeck.cc:606
0xe8eb1d tagged_types_tu_compatible_p
        /workspace/install/gcc/src/gcc/gcc/c/c-typeck.cc:1830
0xe8e35f comptypes_internal
        /workspace/install/gcc/src/gcc/gcc/c/c-typeck.cc:1749
0xe8cbc1 comptypes(tree_node*, tree_node*)
        /workspace/install/gcc/src/gcc/gcc/c/c-typeck.cc:1480
0xf5e39f c_parser_postfix_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:11959
0xf56c00 c_parser_unary_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:10647
0xf55319 c_parser_cast_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:10488
0xf51ad8 c_parser_binary_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:10256
0xf509f7 c_parser_conditional_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:9951
0xf5039d c_parser_expr_no_commas
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:9864
0xf6b9d7 c_parser_expression
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:13918
0xf6c12a c_parser_expression_conv
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:13977
0xf48d73 c_parser_selection_header
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8528
0xf48f4c c_parser_paren_selection_header
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8550
0xf499dd c_parser_if_statement
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8694
0xf471cf c_parser_statement_after_labels
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8212
0xf46e04 c_parser_statement
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8159
0xf49037 c_parser_c99_block_statement
        /workspace/install/gcc/src/gcc/gcc/c/c-parser.cc:8567
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.

The gcc version I used is:
Using built-in specs.
COLLECT_GCC=/workspace/install/gcc/install_15.2.0/bin/gcc
COLLECT_LTO_WRAPPER=/workspace/install/gcc/install_15.2.0/libexec/gcc/x86_64-pc-linux-gnu/15.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /workspace/install/gcc/src/gcc/configure --enable-coverage
--enable-checking --disable-multilib --disable-shared --disable-bootstrap
--enable-languages=c,c++ --prefix=/workspace/install/gcc/install_15.2.0
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 15.2.0 (GCC)