OK, after a long detour that delved deep into codeop and the vagaries of PyCF_DONT_IMPLY_DEDENT (due to a problem that turned out to be due to a missing "\n" in a test case I added), my main conclusion is:

Coupling the "single vs multiple statement" decision to the "implicit print after every call" decision is *really* annoying. The latter should be its own flag *or else* also implied by the "DONT_IMPLY_DEDENT" flag that is already passed to the compiler by codeop.

If *that* gets fixed, then the code module could simply switch over to compiling in exec mode always, without any side effects on the implicit display of expression results.