cmake: determine when to use port.h (#1037)

Allow building using MSYS2 (without MinGW).

CMakeLists.txt

@@ -363,12 +363,14 @@ set (GLOG_SRCS
   src/vlog_is_on.cc
 )
 
-if (CYGWIN OR WIN32)
+# NOTE MSYS2 defines both WIN32 and UNIX. Do not use windows port in this case.
+if ((CYGWIN OR WIN32) AND NOT UNIX)
   list (APPEND GLOG_SRCS
     src/windows/port.cc
     src/windows/port.h
   )
-endif (CYGWIN OR WIN32)
+  set (_glog_USE_WINDOWS_PORT TRUE)
+endif ((CYGWIN OR WIN32) AND NOT UNIX)
 
 add_library (glog_internal OBJECT
   ${_glog_BINARY_CMake_MODULES}
@@ -399,6 +401,12 @@ set (glog_libraries_options_for_static_linking)
 # CMake always uses the generated export header
 target_compile_definitions (glog PUBLIC GLOG_USE_GLOG_EXPORT)
 
+if (_glog_USE_WINDOWS_PORT)
+  target_compile_definitions (glog PRIVATE GLOG_USE_WINDOWS_PORT)
+endif (_glog_USE_WINDOWS_PORT)
+
+unset (_glog_USE_WINDOWS_PORT)
+
 if (WIN32)
   # Do not define min and max as macros
   target_compile_definitions (glog PRIVATE NOMINMAX)

bazel/glog.bzl

@@ -104,6 +104,7 @@ def glog_library(with_gflags = 1, **kwargs):
         "-DGLOG_EXPORT=__declspec(dllexport)",
         "-DGLOG_NO_EXPORT=",
         "-DGLOG_NO_ABBREVIATED_SEVERITIES",
+        "-DGLOG_USE_WINDOWS_PORT",
         "-DHAVE__CHSIZE_S",
         "-I" + src_windows,
     ]

src/stacktrace_windows-inl.h

@@ -34,7 +34,9 @@
 #include <dbghelp.h>
 
 #include "config.h"
-#include "port.h"
+#if defined(GLOG_USE_WINDOWS_PORT)
+#  include "port.h"
+#endif
 #include "stacktrace.h"
 
 namespace google {

src/utilities.h

@@ -57,7 +57,7 @@
 
 #include "glog/logging.h"
 
-#if defined(GLOG_OS_WINDOWS)
+#if defined(GLOG_USE_WINDOWS_PORT)
 #  include "port.h"
 #endif