A generic ($T) -> Type type-fn comptime-evaluated only its return
EXPRESSION, so a local declared before the return ('vs := …; return
make_enum(…, vs)') was unresolved. Now a body with a prelude (statements
before the return) has its full body evaluated: createComptimeFunction-
WithPrelude lowers the pre-return statements into the comptime function's
scope before the return expr, so the locals resolve.
- comptime.zig: createComptimeFunctionWithPrelude (prelude stmts +
expr); evalComptimeTypeBody (extract prelude + return expr, scan the
whole body for declare() forward types); runComptimeTypeFunc factored
out of evalComptimeType (shared bail/declare-never-defined handling).
- generic.zig: route a type-fn body WITH a prelude through
evalComptimeTypeBody; no-prelude bodies stay on evalComptimeType (zero
change for RecvResult/TryResult etc.).
Non-generic builders (whole body already evaluated) and the List-growth
path are unaffected. Suite green (684).