fixup! mingw: rely on MSYS2's metadata instead of hard-coding it

Author: dscho

meson.build

@@ -1271,7 +1271,6 @@ elif host_machine.system() == 'windows'
 
   libgit_c_args += [
     '-DDETECT_MSYS_TTY',
-    '-DENSURE_MSYSTEM_IS_SET',
     '-DNATIVE_CRLF',
     '-DNOGDI',
     '-DNO_POSIX_GOODIES',
@@ -1281,6 +1280,18 @@ elif host_machine.system() == 'windows'
     '-D__USE_MINGW_ANSI_STDIO=0',
   ]
 
+  msystem = get_option('msystem')
+  if msystem != ''
+    mingw_prefix = get_option('mingw_prefix')
+    if mingw_prefix == ''
+      mingw_prefix = '/' + msystem.to_lower()
+    endif
+    libgit_c_args += [
+      '-DENSURE_MSYSTEM_IS_SET="' + msystem + '"',
+      '-DMINGW_PREFIX="' + mingw_prefix + '"'
+    ]
+  endif
+
   libgit_dependencies += compiler.find_library('ntdll')
   libgit_include_directories += 'compat/win32'
   if compiler.get_id() == 'msvc'

meson_options.txt

@@ -21,6 +21,10 @@ option('runtime_prefix', type: 'boolean', value: false,
   description: 'Resolve ancillary tooling and support files relative to the location of the runtime binary instead of hard-coding them into the binary.')
 option('sane_tool_path', type: 'array', value: [],
   description: 'An array of paths to pick up tools from in case the normal tools are broken or lacking.')
+option('msystem', type: 'string', value: '',
+  description: 'Fall-back on Windows when MSYSTEM is not set.')
+option('mingw_prefix', type: 'string', value: '',
+  description: 'Fall-back on Windows when MINGW_PREFIX is not set.')
 
 # Build information compiled into Git and other parts like documentation.
 option('build_date', type: 'string', value: '',