Require `then` and `else` with `if` (#6201)

We previously supported (and primarily used) a non-standard text format for
conditionals in which the condition, if-true expression, and if-false expression
were all simply s-expression children of the `if` expression. The standard text
format, however, requires the use of `then` and `else` forms to introduce the
if-true and if-false arms of the conditional. Update the legacy text parser to
require the standard format and update all tests to match. Update the printer to
print the standard format as well.

The .wast and .wat test inputs were mechanically updated with this script:
https://gist.github.com/tlively/85ae7f01f92f772241ec994c840ccbb1

1 files changed, 58 insertions, 36 deletions

diff --git a/test/lit/passes/heap2local.wast b/test/lit/passes/heap2local.wast
index 37a9e7919..286bfdc19 100644
--- a/test/lit/passes/heap2local.wast
+++ b/test/lit/passes/heap2local.wast
@@ -646,8 +646,10 @@
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (local.get $x)
-  ;; CHECK-NEXT:   (drop
-  ;; CHECK-NEXT:    (ref.null none)
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (drop
+  ;; CHECK-NEXT:     (ref.null none)
+  ;; CHECK-NEXT:    )
   ;; CHECK-NEXT:   )
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (block (result f64)
@@ -666,8 +668,10 @@
     ;; that as a result of this the final local.get has two sets that send it
     ;; values, but we know they are both the same allocation.
     (if (local.get $x)
-      (local.set $ref
-        (local.get $ref)
+      (then
+        (local.set $ref
+          (local.get $ref)
+        )
       )
     )
     (struct.get $struct.A 1
@@ -726,8 +730,10 @@
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (local.get $x)
-  ;; CHECK-NEXT:   (local.set $ref
-  ;; CHECK-NEXT:    (ref.null none)
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (local.set $ref
+  ;; CHECK-NEXT:     (ref.null none)
+  ;; CHECK-NEXT:    )
   ;; CHECK-NEXT:   )
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (struct.get $struct.A 1
@@ -740,8 +746,10 @@
       (struct.new_default $struct.A)
     )
     (if (local.get $x)
-      (local.set $ref
-        (ref.null $struct.A)
+      (then
+        (local.set $ref
+          (ref.null $struct.A)
+        )
       )
     )
     ;; A get that receives two different allocations, and so we should not try
@@ -985,15 +993,17 @@
   ;; CHECK-NEXT:   )
   ;; CHECK-NEXT:   (if
   ;; CHECK-NEXT:    (local.get $x)
-  ;; CHECK-NEXT:    (drop
-  ;; CHECK-NEXT:     (block (result f64)
-  ;; CHECK-NEXT:      (drop
-  ;; CHECK-NEXT:       (ref.null none)
+  ;; CHECK-NEXT:    (then
+  ;; CHECK-NEXT:     (drop
+  ;; CHECK-NEXT:      (block (result f64)
+  ;; CHECK-NEXT:       (drop
+  ;; CHECK-NEXT:        (ref.null none)
+  ;; CHECK-NEXT:       )
+  ;; CHECK-NEXT:       (local.get $3)
   ;; CHECK-NEXT:      )
-  ;; CHECK-NEXT:      (local.get $3)
   ;; CHECK-NEXT:     )
   ;; CHECK-NEXT:    )
-  ;; CHECK-NEXT:    (block
+  ;; CHECK-NEXT:    (else
   ;; CHECK-NEXT:     (drop
   ;; CHECK-NEXT:      (ref.null none)
   ;; CHECK-NEXT:     )
@@ -1025,20 +1035,24 @@
   ;; CHECK-NEXT:   )
   ;; CHECK-NEXT:   (if
   ;; CHECK-NEXT:    (local.get $x)
-  ;; CHECK-NEXT:    (drop
-  ;; CHECK-NEXT:     (block (result i32)
-  ;; CHECK-NEXT:      (drop
-  ;; CHECK-NEXT:       (ref.null none)
+  ;; CHECK-NEXT:    (then
+  ;; CHECK-NEXT:     (drop
+  ;; CHECK-NEXT:      (block (result i32)
+  ;; CHECK-NEXT:       (drop
+  ;; CHECK-NEXT:        (ref.null none)
+  ;; CHECK-NEXT:       )
+  ;; CHECK-NEXT:       (local.get $2)
   ;; CHECK-NEXT:      )
-  ;; CHECK-NEXT:      (local.get $2)
   ;; CHECK-NEXT:     )
   ;; CHECK-NEXT:    )
-  ;; CHECK-NEXT:    (drop
-  ;; CHECK-NEXT:     (block (result f64)
-  ;; CHECK-NEXT:      (drop
-  ;; CHECK-NEXT:       (ref.null none)
+  ;; CHECK-NEXT:    (else
+  ;; CHECK-NEXT:     (drop
+  ;; CHECK-NEXT:      (block (result f64)
+  ;; CHECK-NEXT:       (drop
+  ;; CHECK-NEXT:        (ref.null none)
+  ;; CHECK-NEXT:       )
+  ;; CHECK-NEXT:       (local.get $3)
   ;; CHECK-NEXT:      )
-  ;; CHECK-NEXT:      (local.get $3)
   ;; CHECK-NEXT:     )
   ;; CHECK-NEXT:    )
   ;; CHECK-NEXT:   )
@@ -1062,14 +1076,18 @@
         )
       )
       (if (local.get $x)
-        (drop
-          (struct.get $struct.A 1
-            (local.get $ref)
+        (then
+          (drop
+            (struct.get $struct.A 1
+              (local.get $ref)
+            )
           )
         )
-        (struct.set $struct.A 1
-          (local.get $ref)
-          (f64.const 42)
+        (else
+          (struct.set $struct.A 1
+            (local.get $ref)
+            (f64.const 42)
+          )
         )
       )
       (loop $inner
@@ -1087,14 +1105,18 @@
         )
       )
       (if (local.get $x)
-        (drop
-          (struct.get $struct.A 0
-            (local.get $ref)
+        (then
+          (drop
+            (struct.get $struct.A 0
+              (local.get $ref)
+            )
           )
         )
-        (drop
-          (struct.get $struct.A 1
-            (local.get $ref)
+        (else
+          (drop
+            (struct.get $struct.A 1
+              (local.get $ref)
+            )
           )
         )
       )