[FuzzExec] Give host imported functions exact types

src/tools/execution-results.h

@@ -281,7 +281,7 @@ struct LoggingExternalInterface : public ShellExternalInterface {
     };
     // Use a null instance because this is a host function.
     return Literal(std::make_shared<FuncData>(import->name, nullptr, f),
-                   import->type);
+                   import->type.with(Exact));
   }
 
   void throwJSException() {

test/lit/exec/imported-func.wast

@@ -25,5 +25,7 @@
 ;; CHECK-NEXT: [fuzz-exec] export cast-B-exact
 ;; CHECK-NEXT: [trap cast error]
 ;; CHECK-NEXT: [fuzz-exec] export cast-C-exact
+;; CHECK-NEXT: [fuzz-exec] export cast-host-A-exact
+;; CHECK-NEXT: [fuzz-exec] export cast-host-B
+;; CHECK-NEXT: [trap cast error]
 ;; CHECK-NEXT: [fuzz-exec] export last
-

test/lit/exec/imported-func.wast.second

@@ -8,6 +8,7 @@
  )
 
  (import "primary" "func" (func $fimport (type $A)))
+ (import "fuzzing-support" "log" (func $host-import (type $A)))
 
  (func $cast-A (export "cast-A")
   (drop
@@ -57,8 +58,24 @@
   )
  )
 
+ (func $cast-host-A-exact (export "cast-host-A-exact")
+  ;; Host functions have the exact type of the import.
+  (drop
+   (ref.cast (ref (exact $A))
+    (ref.func $host-import)
+   )
+  )
+ )
+
+ (func $cast-host-B (export "cast-host-B")
+  (drop
+   (ref.cast (ref $B)
+    (ref.func $host-import)
+   )
+  )
+ )
+
  (func $last (export "last")
   ;; Just a non-trapping method to make the test output easier to read.
  )
 )
-