While working on C++20 operator<=>, I noticed that build_new_op_1 was doing
too much conversion when a built-in candidate was selected; the standard
says it should only perform user-defined conversions, and then leave the
normal operator semantics to handle any standard conversions. This is
important for operator<=> because a comparison of two different unscoped
enums is ill-formed; if we promote the enums to int here, cp_build_binary_op
never gets to see the original operand types, so we can't give the error.
I'm also disabling -Wmaybe-uninitialized for expmed.c to avoid the bootstrap
failure from the last time I applied this patch.
* call.c (build_new_op_1): Don't apply any standard conversions to
the operands of a built-in operator. Don't suppress conversions in
cp_build_unary_op.
* typeck.c (cp_build_unary_op): Do integral promotions for enums.
PR tree-optimization/91825
* expmed.c: Reduce -Wmaybe-uninitialized to warning.
From-SVN: r277864
