Reject helpers checked only rc!=0, so a SEGFAULT (exit 139, or the
driver's "w6c failed" exit 1) counted as a clean reject -- a wwstage
crash could pass vacuously (it did, latently, on bodied bare-... pre
#11). Every reject row now captures stderr and requires the actual
diagnostic substring (rc!=0 AND strstr) across all 16 reject tests; a
crash emits no diagnostic, so it now fails. This is the
differential-reject backstop (#15): both stages must cleanly reject
with the expected message.
Two genuine cstage/wwstage diagnostic-body divergences are documented
inline via per-stage substrings, not papered over (845 tuple parse,
catA_f2 tuple arity); catalogued in #21.
A second top-level decl named `main` (fn/let/def/type) collides with
the entry main on the single bare `main` symbol: today both lower to a
bare `main`, w6l silently accepts the duplicate, and the program links
rc=0 then segfaults (or runs wrong), in both stages. The existing
duplicate-decl rejects key on (name, module), so a cross-module
`foo.main` vs the bare entry `main` read as distinct and slip through.
Add a program-global, name-only, cross-module uniqueness check on
`main` in the checker (both stages), colocated with the duplicate-decl
rejects and counting user decls before the -T synthesized test main.
Corpus-safe: a lone `fn main` in any package stays legal (ww has no
package-main convention -- cmatrix/lisp/mandelbrot are non-main-package
entries and keep building). This converts the silent segfault to a
loud compile error and subsumes the w6l silent-dup-main case (#31);
correct package-aware mangling of a non-entry main is deferred to the
root-unit entry-detection work (#22/#32).
Regenerates the w6c and wwdump combined.ww. Table-driven 842 test:
reject rows for let/fn/def/type main (genuine cross-module import form)
plus a negative single-main corpus-safe row that must still build+run.
