Improve message for appleclang
MODIFY
CMakeLists.txt
CMakeLists.txt
@@ -4,8 +4,12 @@ project(vcpkg C CXX)
if(CMAKE_COMPILER_IS_GNUXX OR CMAKE_CXX_COMPILER_ID MATCHES "GNU")
set(GCC 1)
elseif(CMAKE_CXX_COMPILER_ID MATCHES "AppleClang")
- if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS_EQUAL 9.0.0)
- message(FATAL_ERROR "Apple clang versions 9 and below do not have support for the C++ Filesystem TS. Please install gcc6 or newer from homebrew (brew install gcc6).")
+ if(NOT VCPKG_ALLOW_APPLE_CLANG)
+ message(FATAL_ERROR
+"Building the vcpkg tool requires support for the C++ Filesystem TS.
+Apple clang versions 9 and below do not have support for it.
+Please install gcc6 or newer from homebrew (brew install gcc6).
+If you would like to try anyway, set VCPKG_ALLOW_APPLE_CLANG.")
else()
set(CLANG 1)
endif()

Improve message for appleclang