While trying to repro #225 I had this:
cc1plus: fatal error: <source>: No such file or directory
Compiler exited with result code 1
I had opened a new private mode window, clicked the new compiler button twice and edited the options. The middle compiler pane had the error in it.
Opening a new private mode window without closing the old one yields a variant of #225 : the original window has differing compilers (see attachments).
I'm pretty sure this is the same as #212 and so closing it as a duplicate.