From the documentation[1]:
| We're updating the Microsoft C++ preprocessor to improve standards
| conformance, fix longstanding bugs, and change some behaviors that
| are officially undefined. We've also added new diagnostics to warn
| on errors in macro definitions.
Thus it appears to be sensible to switch to the new preprocessor for
all VS17 builds. Note that although the new preprocessor is available
as of VS16.5 (i.e. `version >= 1925`), we don't want to potentially
break older builds, and as such use the new preprocessor only for VS17
builds. Users who wish to use the new preprocessor with VS16, can
still `set CFLAGS=/Zc:preprocessor` before running `buildconf`/`phpize`.
[1] <https://learn.microsoft.com/en-us/cpp/preprocessor/preprocessor-experimental-overview?view=msvc-170>
Closes GH-15201.
d5c4522547