diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
index d8956822..9e77b4e0 100644
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -683,7 +683,7 @@ template <int GRISU_VERSION> struct grisu_shortest_handler {
 };
 
 template <typename Double, FMT_ENABLE_IF_T(sizeof(Double) == sizeof(uint64_t))>
-FMT_FUNC bool grisu_format(Double value, buffer<char>& buf, int precision,
+FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
                            unsigned options, int& exp) {
   FMT_ASSERT(value >= 0, "value is negative");
   bool fixed = (options & grisu_options::fixed) != 0;
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index e3667d06..7bbe63a5 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -21,9 +21,16 @@ if (NOT SUPPORTS_VARIADIC_TEMPLATES)
   target_compile_definitions(gmock PUBLIC GTEST_LANG_CXX11=0)
 endif ()
 
-# Workaround a bug in implementation of variadic templates in MSVC11.
 if (MSVC)
+  # Workaround a bug in implementation of variadic templates in MSVC11.
   target_compile_definitions(gmock PUBLIC _VARIADIC_MAX=10)
+  
+  # Disable MSVC warnings of _CRT_INSECURE_DEPRECATE functions.
+  target_compile_definitions(gmock PUBLIC _CRT_SECURE_NO_WARNINGS)
+  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    # Disable MSVC warnings of POSIX functions.
+    target_compile_options(gmock PUBLIC -Wno-deprecated-declarations)
+  endif ()
 endif ()
 
 # GTest doesn't detect <tuple> with clang.
diff --git a/test/format-test.cc b/test/format-test.cc
index dd65bdd3..c6043586 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -2482,10 +2482,17 @@ TEST(FormatTest, FmtStringInTemplate) {
 
 #endif  // FMT_USE_CONSTEXPR
 
+// C++20 feature test, since r346892 Clang considers char8_t a fundamental
+// type in this mode. If this is the case __cpp_char8_t will be defined.
+#ifndef __cpp_char8_t
+// Locally provide type char8_t defined in format.h
+using fmt::char8_t;
+#endif
+
 TEST(FormatTest, ConstructU8StringViewFromCString) {
   fmt::u8string_view s("ab");
   EXPECT_EQ(s.size(), 2u);
-  const fmt::char8_t* data = s.data();
+  const char8_t* data = s.data();
   EXPECT_EQ(data[0], 'a');
   EXPECT_EQ(data[1], 'b');
 }
@@ -2493,7 +2500,7 @@ TEST(FormatTest, ConstructU8StringViewFromCString) {
 TEST(FormatTest, ConstructU8StringViewFromDataAndSize) {
   fmt::u8string_view s("foobar", 3);
   EXPECT_EQ(s.size(), 3u);
-  const fmt::char8_t* data = s.data();
+  const char8_t* data = s.data();
   EXPECT_EQ(data[0], 'f');
   EXPECT_EQ(data[1], 'o');
   EXPECT_EQ(data[2], 'o');
@@ -2504,7 +2511,7 @@ TEST(FormatTest, U8StringViewLiteral) {
   using namespace fmt::literals;
   fmt::u8string_view s = "ab"_u;
   EXPECT_EQ(s.size(), 2u);
-  const fmt::char8_t* data = s.data();
+  const char8_t* data = s.data();
   EXPECT_EQ(data[0], 'a');
   EXPECT_EQ(data[1], 'b');
   EXPECT_EQ(format("{:*^5}"_u, "🤡"_u), "**🤡**"_u);
@@ -2525,8 +2532,10 @@ TEST(FormatTest, CharTraitsIsNotAmbiguous) {
   // Test that we don't inject internal names into the std namespace.
   using namespace std;
   char_traits<char>::char_type c;
+  (void)c;
 #if __cplusplus >= 201103L
   std::string s;
-  begin(s);
+  auto lval = begin(s);
+  (void)lval;
 #endif
 }
diff --git a/test/posix-mock-test.cc b/test/posix-mock-test.cc
index 75660ea5..fc62627f 100644
--- a/test/posix-mock-test.cc
+++ b/test/posix-mock-test.cc
@@ -461,6 +461,10 @@ struct LocaleMock {
 #  ifdef _MSC_VER
 #    pragma warning(push)
 #    pragma warning(disable : 4273)
+#    ifdef __clang__
+#      pragma clang diagnostic push
+#      pragma clang diagnostic ignored "-Winconsistent-dllimport"
+#    endif
 
 _locale_t _create_locale(int category, const char* locale) {
   return LocaleMock::instance->newlocale(category, locale, 0);
@@ -473,6 +477,9 @@ 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);
 }
+#    ifdef __clang__
+#      pragma clang diagnostic pop
+#    endif
 #    pragma warning(pop)
 #  endif