[NominalFuzzing] SignatureRefining: Ignore exported functions (#4601)

This hits the fuzzer when it tries to call reference exports with a null.

1 files changed, 31 insertions, 0 deletions

diff --git a/test/lit/passes/signature-refining.wast b/test/lit/passes/signature-refining.wast
index fcffcc550..a6d4ba53f 100644
--- a/test/lit/passes/signature-refining.wast
+++ b/test/lit/passes/signature-refining.wast
@@ -624,3 +624,34 @@
     (unreachable)
   )
 )
+
+;; Exports prevent optimization, so $func's type will not change here.
+(module
+  ;; CHECK:      (type $sig (func_subtype (param anyref) func))
+
+  ;; CHECK:      (type $none_=>_none (func_subtype func))
+
+  ;; CHECK:      (type $struct (struct_subtype  data))
+  (type $struct (struct_subtype data))
+
+  (type $sig (func_subtype (param anyref) func))
+
+  ;; CHECK:      (export "prevent-opts" (func $func))
+
+  ;; CHECK:      (func $func (type $sig) (param $x anyref)
+  ;; CHECK-NEXT:  (nop)
+  ;; CHECK-NEXT: )
+  (func $func (export "prevent-opts") (type $sig) (param $x anyref)
+  )
+
+  ;; CHECK:      (func $caller (type $none_=>_none)
+  ;; CHECK-NEXT:  (call $func
+  ;; CHECK-NEXT:   (struct.new_default $struct)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $caller
+    (call $func
+      (struct.new $struct)
+    )
+  )
+)