Avoid compiling CMake itself as C++17 with Clang's MSVC ABI
GUID functions in ATL cause compilation errors with this compiler.
Add the offending case to our check for C++17 support so that it
is not used by default when it does not work.
diff --git a/Source/Checks/cm_cxx17_check.cpp b/Source/Checks/cm_cxx17_check.cpp
index 4e89184..2de10d6 100644
--- a/Source/Checks/cm_cxx17_check.cpp
+++ b/Source/Checks/cm_cxx17_check.cpp
@@ -2,8 +2,21 @@
#include <memory>
#include <unordered_map>
+#ifdef _MSC_VER
+# include <comdef.h>
+#endif
+
int main()
{
std::unique_ptr<int> u(new int(0));
+
+#ifdef _MSC_VER
+ // clang-cl has problems instantiating this constructor in C++17 mode
+ // error: indirection requires pointer operand ('const _GUID' invalid)
+ // return *_IID;
+ IUnknownPtr ptr{};
+ IDispatchPtr disp(ptr);
+#endif
+
return *u;
}
