Emit "elem declare" for functions that need it (#3653)

This adds support for reading (elem declare func $foo .. in the text and
binary formats. We can simply ignore it: we don't need to represent it in
IR, rather we find what needs to be declared when writing. That part takes
a little more work, for which this adds a shared helper function.

1 files changed, 10 insertions, 0 deletions

diff --git a/test/reference-types.wast b/test/reference-types.wast
index e79508839..28e24b4d7 100644
--- a/test/reference-types.wast
+++ b/test/reference-types.wast
@@ -17,6 +17,7 @@
   (func $foo)
 
   (table funcref (elem $take_externref $take_funcref $take_anyref))
+  (elem declare func $ref-taken-but-not-in-table)
 
   (import "env" "import_func" (func $import_func (param externref) (result funcref)))
   (import "env" "import_global" (global $import_global externref))
@@ -532,4 +533,13 @@
     (return (ref.func $foo))
     (return (ref.null func))
   )
+
+  (func $ref-user
+    (drop
+      ;; an "elem declare func" must be emitted for this ref.func which is not
+      ;; in the table
+      (ref.func $ref-taken-but-not-in-table)
+    )
+  )
+  (func $ref-taken-but-not-in-table)
 )