internal/core/adt: propagate default marker in single nested value

If a single value remains of a nested disjunction, the
default marker of the parent should propagate down
regardless of the default marker of the nested value.

This is more in line with evalv2 behavior

Note that in specdeviation.txtar, staged.c now has
two defaults. This seems to be technically
correct, although it is a bit strange.

Fixes #3779

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I09ab6d7d4668884e76cb2c585a8a90da99ba1f18
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1209289
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Matthew Sackman <[email protected]>

Author: mpvl

cue/testdata/cycle/issue429.txtar

@@ -95,7 +95,7 @@ Result:
   s1: (#struct){
     min: (int){ 5 }
     res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
-    max: (number){ |((number){ >5 }, (int){ 5 }) }
+    max: (number){ |(*(int){ 5 }, (number){ >5 }) }
   }
   s2: (#struct){
     max: (int){ 5 }
@@ -194,10 +194,9 @@ diff old new
    s1: (#struct){
 -    res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
 -    min: (int){ 5 }
--    max: (number){ |(*(int){ 5 }, (number){ >5 }) }
 +    min: (int){ 5 }
 +    res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
-+    max: (number){ |((number){ >5 }, (int){ 5 }) }
+     max: (number){ |(*(int){ 5 }, (number){ >5 }) }
    }
    s2: (#struct){
 -    res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }

cue/testdata/disjunctions/defaults.txtar

@@ -44,53 +44,6 @@ issue3779: {
     }
   }
 }
--- out/evalalpha --
-(struct){
-  passToSingleValue: (struct){
-    p1: (_){ |((_){ _ }, (string){ "y" }) }
-    p2: (_){ |((_){ _ }, (string){ "y" }) }
-    p3: (_){ |((string){ "y" }, (_){ _ }) }
-    p4: (_){ |((string){ "y" }, (_){ _ }) }
-  }
-  issue3779: (struct){
-    out: (#struct){
-      fieldFoo: (string){ "foo" }
-      fieldBar: (string){ |((string){ string }, (string){ "foo" }) }
-    }
-    #Foo: (#struct){
-      fieldFoo: (string){ |(*(string){ "foo-default" }, (string){ string }) }
-      fieldBar: (string){ |(*(string){ "foo-default" }, (string){ string }) }
-    }
-    #Bar: (#struct){
-      fieldFoo: (_){ _ }
-      fieldBar: (_){ |(*(_){ _ }, (string){ string }) }
-    }
-  }
-}
--- diff/-out/evalalpha<==>+out/eval --
-diff old new
---- old
-+++ new
-@@ -1,14 +1,14 @@
- (struct){
-   passToSingleValue: (struct){
--    p1: (_){ |(*(string){ "y" }, (_){ _ }) }
--    p2: (_){ |(*(string){ "y" }, (_){ _ }) }
--    p3: (_){ |(*(string){ "y" }, (_){ _ }) }
--    p4: (_){ |(*(string){ "y" }, (_){ _ }) }
-+    p1: (_){ |((_){ _ }, (string){ "y" }) }
-+    p2: (_){ |((_){ _ }, (string){ "y" }) }
-+    p3: (_){ |((string){ "y" }, (_){ _ }) }
-+    p4: (_){ |((string){ "y" }, (_){ _ }) }
-   }
-   issue3779: (struct){
-     out: (#struct){
-       fieldFoo: (string){ "foo" }
--      fieldBar: (string){ |(*(string){ "foo" }, (string){ string }) }
-+      fieldBar: (string){ |((string){ string }, (string){ "foo" }) }
-     }
-     #Foo: (#struct){
-       fieldFoo: (string){ |(*(string){ "foo-default" }, (string){ string }) }
 -- out/eval --
 (struct){
   passToSingleValue: (struct){

cue/testdata/disjunctions/specdeviation.txtar

@@ -76,12 +76,12 @@ Disjuncts:    172
   Q: (int){ |(*(int){ 1 }, (int){ int }) }
   q: (int){ |(*(int){ 1 }, (int){ int }) }
   P: (int){ 2 }
-  p: (int){ |((int){ 2 }, (int){ int }) }
+  p: (int){ |(*(int){ 2 }, (int){ int }) }
   r: (int){ |((int){ 1 }, (int){ 2 }) }
   s: (int){ |(*(int){ 1 }, (int){ 2 }) }
   s1: (#struct){
     min: (int){ 5 }
-    max: (number){ |((number){ >5 }, (int){ 5 }) }
+    max: (number){ |(*(int){ 5 }, (number){ >5 }) }
     res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
   }
   #Size: (#struct){
@@ -90,7 +90,7 @@ Disjuncts:    172
     min: (number){ |(*(int){ 1 }, (number){ >0 }) }
   }
   staged: (struct){
-    c: (string){ |(*(string){ "a" }, (string){ "b" }) }
+    c: (string){ |(*(string){ "a" }, *(string){ "b" }) }
     d: (string){ |(*(string){ "a" }, (string){ "b" }) }
   }
   issue763a: (struct){
@@ -114,28 +114,34 @@ Disjuncts:    172
 diff old new
 --- old
 +++ new
-@@ -2,13 +2,13 @@
-   Q: (int){ |(*(int){ 1 }, (int){ int }) }
-   q: (int){ |(*(int){ 1 }, (int){ int }) }
-   P: (int){ 2 }
--  p: (int){ |(*(int){ 2 }, (int){ int }) }
-+  p: (int){ |((int){ 2 }, (int){ int }) }
+@@ -6,9 +6,9 @@
    r: (int){ |((int){ 1 }, (int){ 2 }) }
    s: (int){ |(*(int){ 1 }, (int){ 2 }) }
    s1: (#struct){
 -    max: (number){ |(*(int){ 5 }, (number){ >5 }) }
 -    res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
      min: (int){ 5 }
-+    max: (number){ |((number){ >5 }, (int){ 5 }) }
++    max: (number){ |(*(int){ 5 }, (number){ >5 }) }
 +    res: (int){ |(*(int){ 0 }, (int){ &(>=0, int) }) }
    }
    #Size: (#struct){
      max: (number){ |(*(int){ 1 }, (number){ >0 }, (number){ >1 }) }
+@@ -16,7 +16,7 @@
+     min: (number){ |(*(int){ 1 }, (number){ >0 }) }
+   }
+   staged: (struct){
+-    c: (string){ |(*(string){ "a" }, (string){ "b" }) }
++    c: (string){ |(*(string){ "a" }, *(string){ "b" }) }
+     d: (string){ |(*(string){ "a" }, (string){ "b" }) }
+   }
+   issue763a: (struct){
 -- diff/explanation --
 The changes in default behavior as are shown here are according to spec, as is
 described at the top of the file. These changes may pose too much of a problem
 for the transition to the new evaluator, though.
-TODO: consider reintroducing bugs.
+UPDATE: we have made evalv3 a bit more in line with evalv2. Note how this
+affects staged.c, though.
+TODO(defaults): consider these cases with a potential default redesign.
 -- diff/todo/p3 --
 Reordering.
 -- out/eval --

internal/core/adt/disjunct2.go

@@ -384,7 +384,9 @@ func (n *nodeContext) processDisjunctions() *Bottom {
 	case 1:
 		d := cross[0].node
 		n.setBaseValue(d)
-		n.defaultMode = cross[0].defaultMode
+		if n.defaultMode == maybeDefault {
+			n.defaultMode = cross[0].defaultMode
+		}
 		if n.defaultAttemptInCycle != nil && n.defaultMode != isDefault {
 			c := n.ctx
 			path := c.PathToString(n.defaultAttemptInCycle.Path())
@@ -574,7 +576,8 @@ func (n *nodeContext) doDisjunct(c Conjunct, m defaultMode, mode runMode, hole i
 		return nil, err
 	}
 
-	d = d.node.DerefDisjunct().state
+	d.node.DerefDisjunct().state.defaultMode = d.defaultMode
+	d = d.node.DerefDisjunct().state // TODO: maybe do not unroll at all.
 
 	return d, nil
 }