Don't use POSIX API on UWP

include/fmt/posix.h

@@ -26,7 +26,12 @@
 
 #include "format.h"
 
-#if FMT_HAS_INCLUDE("fcntl.h")
+// UWP doesn't provide _pipe.
+#if FMT_HAS_INCLUDE("winapifamily.h")
+#  include <winapifamily.h>
+#endif
+#if FMT_HAS_INCLUDE("fcntl.h") && \
+    (!defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
 #  include <fcntl.h>  // for O_RDONLY
 #  define FMT_USE_FCNTL 1
 #else
@@ -60,7 +65,7 @@
 #ifndef _WIN32
 #  define FMT_RETRY_VAL(result, expression, error_result) \
     do {                                                  \
-      (result) = (expression);                              \
+      (result) = (expression);                            \
     } while ((result) == (error_result) && errno == EINTR)
 #else
 #  define FMT_RETRY_VAL(result, expression, error_result) result = (expression)

test/CMakeLists.txt

@@ -116,7 +116,6 @@ if (NOT MSVC_BUILD_STATIC)
     posix-mock-test.cc ../src/format.cc ${TEST_MAIN_SRC})
   target_include_directories(
     posix-mock-test PRIVATE ${PROJECT_SOURCE_DIR}/include)
-  target_compile_definitions(posix-mock-test PRIVATE FMT_USE_FILE_DESCRIPTORS=1)
   target_link_libraries(posix-mock-test gmock)
   target_include_directories(posix-mock-test SYSTEM PUBLIC gtest gmock)
   if (FMT_PEDANTIC)

test/gtest-extra.cc

@@ -78,7 +78,7 @@ std::string read(file& f, std::size_t count) {
   return buffer;
 }
 
-#endif  // FMT_USE_FILE_DESCRIPTORS
+#endif  // FMT_USE_FCNTL
 
 std::string format_system_error(int error_code, fmt::string_view message) {
   fmt::memory_buffer out;