Fix/suppress MSVC warnings

test/format-impl-test.cc

@@ -171,7 +171,7 @@ TEST(FormatTest, WriteToOStreamMaxSize) {
     EXPECT_CALL(buffer, xsputn(data, static_cast<std::streamsize>(n)))
         .WillOnce(testing::Return(max_streamsize));
     data += n;
-    size -= n;
+    size -= static_cast<std::size_t>(n);
   } while (size != 0);
   fmt::write(os, w);
 }

test/gtest-extra-test.cc

@@ -46,7 +46,7 @@ namespace {
 std::string sanitize(const std::string &s) {
   std::string result;
   for (std::string::const_iterator i = s.begin(), end = s.end(); i != end; ++i)
-    result.push_back(*i & static_cast<char>(0xff));
+    result.push_back(static_cast<char>(*i & 0xff));
   return result;
 }
 

test/posix-mock-test.cc

@@ -487,6 +487,9 @@ struct LocaleMock {
 } *LocaleMock::instance;
 
 #ifdef _MSC_VER
+# pragma warning(push)
+# pragma warning(disable: 4273)
+
 _locale_t _create_locale(int category, const char *locale) {
   return LocaleMock::instance->newlocale(category, locale, 0);
 }
@@ -498,6 +501,7 @@ void _free_locale(_locale_t locale) {
 double _strtod_l(const char *nptr, char **endptr, _locale_t locale) {
   return LocaleMock::instance->strtod_l(nptr, endptr, locale);
 }
+# pragma warning(pop)
 #endif
 
 LocaleType newlocale(int category_mask, const char *locale, LocaleType base) {

test/printf-test.cc

@@ -379,7 +379,7 @@ TEST(PrintfTest, Bool) {
 TEST(PrintfTest, Int) {
   EXPECT_PRINTF("-42", "%d", -42);
   EXPECT_PRINTF("-42", "%i", -42);
-  unsigned u = -42u;
+  unsigned u = 0 - 42u;
   EXPECT_PRINTF(fmt::format("{}", u), "%u", -42);
   EXPECT_PRINTF(fmt::format("{:o}", u), "%o", -42);
   EXPECT_PRINTF(fmt::format("{:x}", u), "%x", -42);