IntelliSense cannot find structure member references

Environment

Latest everything:

Version: 1.93.1 (system setup)
Commit: 38c31bc77e0dd6ae88a4e9cc93428cc27a56ba40
Date: 2024-09-11T17:20:05.685Z
Electron: 30.4.0
ElectronBuildId: 10073054
Chromium: 124.0.6367.243
Node.js: 20.15.1
V8: 12.4.254.20-electron.0
OS: Windows_NT x64 10.0.19045

Bug Summary and Steps to Reproduce

Consider the following code (test.c):

#include <stdio.h>
#include <stdlib.h>

typedef unsigned int   uint4;
typedef   signed int    int4;
typedef unsigned short uint2;
typedef   signed short  int2;
typedef unsigned char  uint1;
typedef   signed char   int1;

#if defined(_MSC_VER)
#  define PACKED(...)                           \
    __pragma(pack(push, 1))                     \
    __VA_ARGS__                                 \
    __pragma(pack(pop))
#else
#  if defined(__GNUC__)
#    define PACKED(...)                         \
    __VA_ARGS__                                 \
    __attribute__((packed))
#  endif
#endif

PACKED(struct S_newstruct {
    uint1   member1;
    uint2   member2[2];
    uint4   sys$member3;
    uint4   sys$member4[2];
});

int main(void)
{
    struct S_newstruct* s = malloc(sizeof(*s));
    printf("%u\n", s->member1);
    return 0;
}

If you try to "Go to references" while on member1 in the definition of structure S_newstruct, you'll get "No references found", not even that in the printf() statement in main(). That's very unexpected, and makes IntelliSense basically useless.

Configuration and Logs

$ cat .vscode/c_cpp_properties.json
{
    "configurations": [
        {
            "name": "Win32",
            "defines": [
                "_DEBUG",
                "UNICODE",
                "_UNICODE",
                "_GNU_SOURCE=1",
                "__CYGWIN__"
            ],
            "compilerPath": "C:/cygwin64/bin/gcc.exe",
            "compilerArgs": [ "-fms-extensions" ],
            "cStandard": "c17",
            "cppStandard": "c++17"
        }
    ],
    "version": 4
}

Other Extensions

No response

Additional context

No response

Reproduce the missing reference result using test.c and the configuration in .vscode/c_cpp_properties.json, with the Cygwin compiler settings shown. Start from the IntelliSense "Go to references" entry point for the member1 definition. Done means references from the structure definition include the member1 use in main().