fix(rt): handle fun-type closure env refs in callee setup (#956)

- Extend closure callee setup (`setupCalleeClosure2`) to accept
closure-env references whose pointee resolves to `typeInfoFunType` (in
addition to `typeInfoVoidType`).
- Add `isFunType(TypeInfo)` helper predicate used by that guard.
- In the fix commit, refresh `closure_access_struct-fail.main.expected`
to show the behavior change from stuck frontier to terminal
`#EndProgram`.
- Cleanup after fix:
  - rename `closure_access_struct-fail.rs` -> `closure_access_struct.rs`
  - remove `show/closure_access_struct-fail.main.expected`
  - remove this case from `PROVE_RS_SHOW_SPECS`

Author: Stevengre

kmir/src/kmir/kdist/mir-semantics/kmir.md

@@ -581,16 +581,22 @@ Therefore a heuristics is used here:
                // or the closure ref type pointee is missing from the type table
      andBool isRefType(lookupTy(tyOfLocal({LOCALS[CLOSURE]}:>TypedLocal)))
      andBool isTy(pointeeTy(lookupTy(tyOfLocal({LOCALS[CLOSURE]}:>TypedLocal))))
-     andBool lookupTy({pointeeTy(lookupTy(tyOfLocal({LOCALS[CLOSURE]}:>TypedLocal)))}:>Ty) ==K typeInfoVoidType
+     andBool (
+               lookupTy({pointeeTy(lookupTy(tyOfLocal({LOCALS[CLOSURE]}:>TypedLocal)))}:>Ty) ==K typeInfoVoidType
+               orBool isFunType(lookupTy({pointeeTy(lookupTy(tyOfLocal({LOCALS[CLOSURE]}:>TypedLocal)))}:>Ty))
+             )
     [priority(45), preserves-definedness]
 
   syntax Bool ::= isTupleType ( TypeInfo ) [function, total]
                 | isRefType ( TypeInfo ) [function, total]
+                | isFunType ( TypeInfo ) [function, total]
   // -------------------------------------------------------
   rule isTupleType(typeInfoTupleType(_, _)) => true
   rule isTupleType(    _                  ) => false [owise]
   rule isRefType(typeInfoRefType(_)) => true
   rule isRefType(    _             ) => false [owise]
+  rule isFunType(typeInfoFunType(_)) => true
+  rule isFunType(    _             ) => false [owise]
 
   syntax KItem ::= #setTupleArgs ( Int , Value )
                  | #setTupleArgs ( Int , List )

…a/prove-rs/closure_access_struct-fail.rs …n/data/prove-rs/closure_access_struct.rskmir/src/tests/integration/data/prove-rs/closure_access_struct-fail.rs renamed to kmir/src/tests/integration/data/prove-rs/closure_access_struct.rs kmir/src/tests/integration/data/prove-rs/closure_access_struct-fail.rs renamed to kmir/src/tests/integration/data/prove-rs/closure_access_struct.rs

@@ -64,7 +64,6 @@
     'ref-ptr-cast-elem-fail',
     'ref-ptr-cast-elem-offset-fail',
     'and_then_closure-fail',
-    'closure_access_struct-fail',
 ]