In giscanner/dumper.py the init function of the DumpCompiler class has a check for "cl" in the compiler command. If that matches, it does assume you're using a Microsoft compiler.

Unfortunately, clang also has cl as substring. Therefore Microsoft compiler arguments are passed to clang, which makes compiles fail.

See the following snippet, line 92:

>        if 'cl' in self._compiler_cmd:
>            self._pkgconfig_msvc_flags = '--msvc-syntax'

The if could be replaced with the following line:

>        if not 'clang' in self._compiler_cmd and 'cl' in self._compiler_cmd:

I don't know if there's a cleaner way to fix it.