Implement `array` basic heap type (#5148)

`array` is the supertype of all defined array types and for now is a subtype of
`data`. (Once `data` becomes `struct` this will no longer be true.) Update the
binary and text parsing of `array.len` to ignore the obsolete type annotation
and update the binary emitting to emit a zero in place of the old type
annotation and the text printing to print an arbitrary heap type for the
annotation. A follow-on PR will add support for the newer unannotated version of
`array.len`.

1 files changed, 8 insertions, 7 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index ddd8f9cc1..0f4a314ae 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -108,6 +108,9 @@ bool maybePrintRefShorthand(std::ostream& o, Type type) {
       case HeapType::data:
         o << "dataref";
         return true;
+      case HeapType::array:
+        o << "arrayref";
+        return true;
       case HeapType::string:
         o << "stringref";
         return true;
@@ -2234,11 +2237,12 @@ struct PrintExpressionContents
     TypeNamePrinter(o, wasm).print(curr->ref->type.getHeapType());
   }
   void visitArrayLen(ArrayLen* curr) {
-    if (printUnreachableOrNullReplacement(curr->ref)) {
-      return;
-    }
     printMedium(o, "array.len ");
-    TypeNamePrinter(o, wasm).print(curr->ref->type.getHeapType());
+    if (curr->ref->type == Type::unreachable) {
+      TypeNamePrinter(o, wasm).print(HeapType::array);
+    } else {
+      TypeNamePrinter(o, wasm).print(curr->ref->type.getHeapType());
+    }
   }
   void visitArrayCopy(ArrayCopy* curr) {
     if (printUnreachableOrNullReplacement(curr->srcRef) ||
@@ -2801,9 +2805,6 @@ struct PrintSExpression : public UnifiedExpressionVisitor<PrintSExpression> {
   void visitArrayGet(ArrayGet* curr) {
     maybePrintUnreachableOrNullReplacement(curr, curr->ref->type);
   }
-  void visitArrayLen(ArrayLen* curr) {
-    maybePrintUnreachableOrNullReplacement(curr, curr->ref->type);
-  }
   // Module-level visitors
   void printSupertypeOr(HeapType curr, std::string noSuper) {
     if (auto super = curr.getSuperType()) {