Signed / unsigned comparison warning on MSVC

What version of protobuf and what language are you using?
Version: v25.1 (actually a bit after, main from 20231123. Relevant code hasn't changed since then)
Language: C++

What operating system (Linux, Windows, ...) and version?
Windows 11 Pro 22H2

What runtime / compiler are you using (e.g., python version or gcc version)
MS Visual Studio 17.8.0 (tool version 14.37.32822)

What did you do?
Compile something that makes use of include/google/protobuf/map.h

What did you expect to see
Warning-free compilation

What did you see instead?
Warnings from Abseil : include\absl\log\internal\check_op.h(340,1): warning C4018: '>=': signed/unsigned mismatch
This is from an Abseil macro that generates Check_GEImpl(), used in map.h

Anything else we should know about your project / environment

map.h line 1041 (in current main) invokes

ABSL_DCHECK_GE(new_num_buckets, kMinTableSize);

the first arg is map_index_t which resolves to uint32_t, whereas the second is defined
at line 528 as

enum { kMinTableSize = 16 / sizeof(void*) };

I'm guess MSVC is choosing a signed type for the enum which is causing the problem. Changing it to

enum : unsigned int { kMinTableSize = 16 / sizeof(void*) };

makes the warnings go away

Start by compiling a small C++ use of include/google/protobuf/map.h with MSVC and inspect map.h around lines 528 and 1041, where kMinTableSize is compared with map_index_t. Check the warning path through include/absl/log/internal/check_op.h:340. Done means the comparison compiles without MSVC signed/unsigned warning.