https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105050
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- I think just "note: neither branch of ‘if’ is a valid ‘constexpr’ body" without the "because ..." and the following notes would be good enough. It tells the user to look at the 'if' body, not the condition on the line highlighted by the caret. It's still OK for the caret to show the 'if' itself, because the note now makes it clear that it's the *body* of that 'if' that is the problem.
