Fix compilation on MinGW with native threads

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

@@ -396,10 +396,16 @@
 #  include <io.h>
 # endif
 // In order to avoid having to include <windows.h>, use forward declaration
-// assuming CRITICAL_SECTION is a typedef of _RTL_CRITICAL_SECTION.
+#if GTEST_OS_WINDOWS_MINGW
+// MinGW defined _CRITICAL_SECTION and _RTL_CRITICAL_SECTION as two
+// separate (equivalent) structs, instead of using typedef
+typedef struct _CRITICAL_SECTION GTEST_CRITICAL_SECTION;
+#else
+// Assume CRITICAL_SECTION is a typedef of _RTL_CRITICAL_SECTION.
 // This assumption is verified by
 // WindowsTypesTest.CRITICAL_SECTIONIs_RTL_CRITICAL_SECTION.
-struct _RTL_CRITICAL_SECTION;
+typedef struct _RTL_CRITICAL_SECTION GTEST_CRITICAL_SECTION;
+#endif
 #else
 // This assumes that non-Windows OSes provide unistd.h. For OSes where this
 // is not the case, we need to include headers that provide the functions
@@ -1693,7 +1699,7 @@ class GTEST_API_ Mutex {
   // by the linker.
   MutexType type_;
   long critical_section_init_phase_;  // NOLINT
-  _RTL_CRITICAL_SECTION* critical_section_;
+  GTEST_CRITICAL_SECTION* critical_section_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(Mutex);
 };

googletest/test/gtest-port_test.cc

@@ -1295,9 +1295,16 @@ TEST(WindowsTypesTest, HANDLEIsVoidStar) {
   StaticAssertTypeEq<HANDLE, void*>();
 }
 
+#if GTEST_OS_WINDOWS_MINGW
+TEST(WindowsTypesTest, _CRITICAL_SECTIONIs_CRITICAL_SECTION) {
+  StaticAssertTypeEq<CRITICAL_SECTION, _CRITICAL_SECTION>();
+}
+#else
 TEST(WindowsTypesTest, CRITICAL_SECTIONIs_RTL_CRITICAL_SECTION) {
   StaticAssertTypeEq<CRITICAL_SECTION, _RTL_CRITICAL_SECTION>();
 }
+#endif
+
 #endif  // GTEST_OS_WINDOWS
 
 }  // namespace internal

googletest/test/gtest_unittest.cc

@@ -442,7 +442,7 @@ class FormatEpochTimeInMillisAsIso8601Test : public Test {
     // tzset() distinguishes between the TZ variable being present and empty
     // and not being present, so we have to consider the case of time_zone
     // being NULL.
-#if _MSC_VER
+#if _MSC_VER || GTEST_OS_WINDOWS_MINGW
     // ...Unless it's MSVC, whose standard library's _putenv doesn't
     // distinguish between an empty and a missing variable.
     const std::string env_var =