[Bug d/91595] New: Version (Windows) is not defined in GCC D Compiler

[ray_linn at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91595

            Bug ID: 91595
           Summary: Version (Windows) is not defined in GCC D Compiler
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: ray_linn at hotmail dot com
  Target Milestone: ---

when build Druntime with msys2/mingw-w64 on Windows 10, it looks version
(Windows) is not defined into the compiler.

The trouble appears while building libdruntime

EXAMPLE: libphobos\libdruntime\core\stdc\time.d
error: undefined identifier 'time_t'
error: undefined identifier 'tm'

Manually add

version (GNU) {
    alias c_long time_t;
    alias c_long clock_t;
}

into time.d then it compiles but it seems weird.

The trouble is that there are many other similar errors
with core\stdc\stddef.d, stdlib.d, stdint.d, etc ...