Only set `supertype` if nominal typing is enabled (#3958)

The code for printing and emitting the experimental nominal type constructors
added in #3933 assumes that supertypes were only returned from `getSuperType`
when nominal typing was enabled. `getSuperType` in turn was assuming that the
supertype field would only be set if nominal typing was enabled, but this was
not the case. This bug caused use-after-free errors because equirecursive
canonicalization left the supertype field pointing to a temporary HeapTypeInfo
that would be freed at the end of parsing but then accessed during module
writing.

To fix the issue, only set `supertype` if nominal typing is enabled, as
originally intended.

1 files changed, 45 insertions, 25 deletions

diff --git a/test/lit/nominal-good.wast b/test/lit/nominal-good.wast
index 8fff43d6a..4110fb96b 100644
--- a/test/lit/nominal-good.wast
+++ b/test/lit/nominal-good.wast
@@ -1,46 +1,66 @@
 ;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
-;; RUN: wasm-opt %s -all --nominal -S -o - | filecheck %s
-;; RUN: wasm-opt %s -all --nominal --roundtrip -S -o - | filecheck %s
+;; RUN: wasm-opt %s -all --nominal -S -o - | filecheck %s --check-prefix NOMINAL
+;; RUN: wasm-opt %s -all --nominal --roundtrip -S -o - | filecheck %s --check-prefix NOMINAL
+;; RUN: wasm-opt %s -all -S -o - | filecheck %s --check-prefix EQUIREC
+;; RUN: wasm-opt %s -all --roundtrip -S -o - | filecheck %s --check-prefix EQUIREC
 
 (module
 
-  ;; CHECK:      (type $super-struct (struct (field i32)))
-  ;; CHECK:      (type $sub-struct (struct (field i32) (field i64)) (extends $super-struct))
-  (type $sub-struct (struct i32 i64) (extends $super-struct))
+  ;; NOMINAL:      (type $super-struct (struct (field i32)))
+  ;; EQUIREC:      (type $super-struct (struct (field i32)))
   (type $super-struct (struct i32))
 
-  ;; CHECK:      (type $super-array (array (ref $super-struct)))
-  ;; CHECK:      (type $sub-array (array (ref $sub-struct)) (extends $super-array))
-  (type $sub-array (array (ref $sub-struct)) (extends $super-array))
+  ;; NOMINAL:      (type $sub-struct (struct (field i32) (field i64)) (extends $super-struct))
+  ;; EQUIREC:      (type $sub-struct (struct (field i32) (field i64)))
+  (type $sub-struct (struct i32 i64) (extends $super-struct))
+
+  ;; NOMINAL:      (type $super-array (array (ref $super-struct)))
+  ;; EQUIREC:      (type $super-array (array (ref $super-struct)))
   (type $super-array (array (ref $super-struct)))
 
-  ;; TODO: signature types as well, once functions store their HeapTypes.
+  ;; NOMINAL:      (type $sub-array (array (ref $sub-struct)) (extends $super-array))
+  ;; EQUIREC:      (type $sub-array (array (ref $sub-struct)))
+  (type $sub-array (array (ref $sub-struct)) (extends $super-array))
 
-  ;; CHECK:      (func $make-sub-struct (result (ref $sub-struct))
-  ;; CHECK-NEXT:  (unreachable)
-  ;; CHECK-NEXT: )
-  (func $make-sub-struct (result (ref $sub-struct))
-    (unreachable)
-  )
+  ;; TODO: signature types as well, once functions store their HeapTypes.
 
-  ;; CHECK:      (func $make-super-struct (result (ref $super-struct))
-  ;; CHECK-NEXT:  (call $make-sub-struct)
-  ;; CHECK-NEXT: )
+  ;; NOMINAL:      (func $make-super-struct (result (ref $super-struct))
+  ;; NOMINAL-NEXT:  (call $make-sub-struct)
+  ;; NOMINAL-NEXT: )
+  ;; EQUIREC:      (func $make-super-struct (result (ref $super-struct))
+  ;; EQUIREC-NEXT:  (call $make-sub-struct)
+  ;; EQUIREC-NEXT: )
   (func $make-super-struct (result (ref $super-struct))
     (call $make-sub-struct)
   )
 
-  ;; CHECK:      (func $make-sub-array (result (ref $sub-array))
-  ;; CHECK-NEXT:  (unreachable)
-  ;; CHECK-NEXT: )
-  (func $make-sub-array (result (ref $sub-array))
+  ;; NOMINAL:      (func $make-sub-struct (result (ref $sub-struct))
+  ;; NOMINAL-NEXT:  (unreachable)
+  ;; NOMINAL-NEXT: )
+  ;; EQUIREC:      (func $make-sub-struct (result (ref $sub-struct))
+  ;; EQUIREC-NEXT:  (unreachable)
+  ;; EQUIREC-NEXT: )
+  (func $make-sub-struct (result (ref $sub-struct))
     (unreachable)
   )
 
-  ;; CHECK:      (func $make-super-array (result (ref $super-array))
-  ;; CHECK-NEXT:  (call $make-sub-array)
-  ;; CHECK-NEXT: )
+  ;; NOMINAL:      (func $make-super-array (result (ref $super-array))
+  ;; NOMINAL-NEXT:  (call $make-sub-array)
+  ;; NOMINAL-NEXT: )
+  ;; EQUIREC:      (func $make-super-array (result (ref $super-array))
+  ;; EQUIREC-NEXT:  (call $make-sub-array)
+  ;; EQUIREC-NEXT: )
   (func $make-super-array (result (ref $super-array))
     (call $make-sub-array)
   )
+
+  ;; NOMINAL:      (func $make-sub-array (result (ref $sub-array))
+  ;; NOMINAL-NEXT:  (unreachable)
+  ;; NOMINAL-NEXT: )
+  ;; EQUIREC:      (func $make-sub-array (result (ref $sub-array))
+  ;; EQUIREC-NEXT:  (unreachable)
+  ;; EQUIREC-NEXT: )
+  (func $make-sub-array (result (ref $sub-array))
+    (unreachable)
+  )
 )