[threads] Validate all features required by ref.null (#6758)

`ref.null` of shared types should only be allowed when shared-everything
is enabled, but we were previously checking only that reference types
were enabled when validating `ref.null`. Update the code to check all
features required by the null type and factor out shared logic for
printing lists of missing feature options in error messages.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/wasm-builder.h b/src/wasm-builder.h
index 1e768b11c..6663417f8 100644
--- a/src/wasm-builder.h
+++ b/src/wasm-builder.h
@@ -1217,8 +1217,10 @@ public:
     if (type.isFunction()) {
       return makeRefFunc(value.getFunc(), type.getHeapType());
     }
-    if (type.isRef() && type.getHeapType() == HeapType::i31) {
-      return makeRefI31(makeConst(value.geti31()));
+    if (type.isRef() && type.getHeapType().isBasic() &&
+        type.getHeapType().getBasic(Unshared) == HeapType::i31) {
+      return makeRefI31(makeConst(value.geti31()),
+                        type.getHeapType().getShared());
     }
     if (type.isString()) {
       // The string is already WTF-16, but we need to convert from `Literals` to