Preserve Function HeapTypes (#3952)

When using nominal types, func.ref of two functions with identical signatures
but different HeapTypes will yield different types. To preserve these semantics,
Functions need to track their HeapTypes, not just their Signatures.

This PR replaces the Signature field in Function with a HeapType field and adds
new utility methods to make it almost as simple to update and query the function
HeapType as it was to update and query the Function Signature.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/abi/js.h b/src/abi/js.h
index 118a2c981..970f7ffa7 100644
--- a/src/abi/js.h
+++ b/src/abi/js.h
@@ -18,6 +18,7 @@
 #define wasm_abi_abi_h
 
 #include "asmjs/shared-constants.h"
+#include "wasm-builder.h"
 #include "wasm.h"
 
 namespace wasm {
@@ -64,9 +65,7 @@ inline void ensureHelpers(Module* wasm,
     if (specific.is() && name != specific) {
       return;
     }
-    auto func = make_unique<Function>();
-    func->name = name;
-    func->sig = Signature(params, results);
+    auto func = Builder::makeFunction(name, Signature(params, results), {});
     func->module = ENV;
     func->base = name;
     wasm->addFunction(std::move(func));