https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79937
--- Comment #18 from Jakub Jelinek <jakub at gcc dot gnu.org> --- struct Y { static Y bar (Y y) { return y; } int i; int n = bar (Y{2,i}).m + bar {Y{2,i,i}).n; int m = i; }; is rejected, so I can't find a counter-example where PLACEHOLDER_EXPRs for different objects would be intermixed in the same CONSTRUCTOR (assuming there must be a CONSTRUCTOR).