This is based on clang --- it's not a new compiler.
<tangent>
Are the any working open source C++ compilers which aren't based on gcc or clang? I know of TenDRA, which appears to have ceased to exist and was always kind of incomprehensible and non-working and apparently it never got as far as STL support; there Path64, whose github page no longer contains the compiler repo; there's Open64, whose website no longer exists (although there does seem to be a daughter project, OpenUH, which did a release last year)...
<tangent>
Are the any working open source C++ compilers which aren't based on gcc or clang? I know of TenDRA, which appears to have ceased to exist and was always kind of incomprehensible and non-working and apparently it never got as far as STL support; there Path64, whose github page no longer contains the compiler repo; there's Open64, whose website no longer exists (although there does seem to be a daughter project, OpenUH, which did a release last year)...
Is there anything else?