Typed continuations: update syntax of handler clauses (#6824)

The syntax for handler clauses in `resume` instructions has recently
changed, using `on` instead of `tag` now.

Instead of 
```
(resume $ct (tag $tag0 $block0) ...  (tag $tagn $blockn))
```

we now have

```
(resume $ct (on $tag0 $block0) ...  (on $tagn $blockn))
```

This PR adapts parsing, printing, and some tests accordingly.

(Note that this PR deliberately makes none of the other changes that
will arise from implementing the new, combined stack switching proposal,
yet.)

2 files changed, 3 insertions, 5 deletions

diff --git a/src/parser/parsers.h b/src/parser/parsers.h
index e3434d1e6..ef46a395a 100644
--- a/src/parser/parsers.h
+++ b/src/parser/parsers.h
@@ -2426,7 +2426,7 @@ makeContNew(Ctx& ctx, Index pos, const std::vector<Annotation>& annotations) {
   return ctx.makeContNew(pos, annotations, *type);
 }
 
-// resume ::= 'resume' typeidx ('(' 'tag' tagidx labelidx ')')*
+// resume ::= 'resume' typeidx ('(' 'on' tagidx labelidx ')')*
 template<typename Ctx>
 Result<>
 makeResume(Ctx& ctx, Index pos, const std::vector<Annotation>& annotations) {
@@ -2434,7 +2434,7 @@ makeResume(Ctx& ctx, Index pos, const std::vector<Annotation>& annotations) {
   CHECK_ERR(type);
 
   auto tagLabels = ctx.makeTagLabelList();
-  while (ctx.in.takeSExprStart("tag"sv)) {
+  while (ctx.in.takeSExprStart("on"sv)) {
     auto tag = tagidx(ctx);
     CHECK_ERR(tag);
     auto label = labelidx(ctx);
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 5c83e89f1..8bf30702c 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -2374,11 +2374,9 @@ struct PrintExpressionContents
     o << ' ';
     printHeapType(curr->contType);
 
-    // We deliberate keep all (tag ...) clauses on the same line as the resume
-    // itself to work around a quirk in update_lit_checks.py
     for (Index i = 0; i < curr->handlerTags.size(); i++) {
       o << " (";
-      printMedium(o, "tag ");
+      printMedium(o, "on ");
       curr->handlerTags[i].print(o);
       o << ' ';
       curr->handlerBlocks[i].print(o);