[Bug]: "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros" on fedora:rawhide

[rouault]

Describe the issue

On latest fedora:rawhide, both with clang++ (19.1.6) or g++ (15.0.1), in implicit mode or explicit -std=c++17, including gtest.h emits:

/usr/bin/../lib/gcc/x86_64-redhat-linux/15/../../../../include/c++/15/ciso646:46:4: warning: "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros"
   46 | #  warning "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros"
      |    ^

workaround: use explicit -std=c++20

Steps to reproduce the problem

docker run --rm -it fedora:rawhide

install gtest 1.15.2 in it
include gtest.h

What version of GoogleTest are you using?

1.15.2

What operating system and version are you using?

# cat /etc/redhat-release 
Fedora release 41 (Rawhide)

What compiler and version are you using?

clang++ (19.1.6) or g++ (15.0.1)

What build system are you using?

all

Additional context

No response

[dkaszews]

From cppreference:

is removed in C++20. Corresponding <iso646.h> is still available in C++20.

Sounds like we can just change

googletest/googletest/include/gtest/internal/gtest-port.h

Line 295 in 4a00a24

#include <ciso646> // Pre-C++20

to #include <iso646.h>.

@rouault Could you try if that fixes the warning?

[rouault]

I just tested the following:

# dnf install clang
# echo "#include <iso646.h>" > test.cc
# clang++ -std=c++17 -c test.cc
# g++ -std=c++17 -c test.cc