internal/core/adt: remove unnecessary check

The removed check used to be necessary to stop on cycles,
but the new structural cycle detection makes this no
longer necessary.

Note that CUE is allowed to report an error that occurs
on multiple locations on only one of them.

Fixes #2244

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: Ib8979ce3b45597fbcc4e3a4b4f88811773ffdd80
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/549659
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

cue/testdata/cycle/025_cannot_resolve_references_that_would_be_ambiguous.txtar

@@ -55,22 +55,21 @@ c2: (*{
 }
 -- out/eval/stats --
 Leaks:  0
-Freed:  48
-Reused: 39
+Freed:  52
+Reused: 43
 Allocs: 9
-Retain: 12
+Retain: 19
 
 Unifications: 24
-Conjuncts:    72
-Disjuncts:    46
+Conjuncts:    81
+Disjuncts:    52
 -- out/eval --
 (struct){
   a1: (_|_){
-    // [incomplete] a1: incomplete cause disjunction
-  }
-  a2: (_|_){
-    // [incomplete] a2: incomplete cause disjunction
+    // [cycle] cycle error:
+    //     ./in.cue:2:5
   }
+  a2: (int){ 1 }
   a3: (int){ 1 }
   b1: (int){ |((int){ 0 }, (int){ 1 }) }
   b2: (int){ |((int){ 0 }, (int){ 1 }) }

cue/testdata/cycle/issue241.txtar

@@ -25,23 +25,22 @@ a: cell.a
 b: cell.b
 -- out/eval/stats --
 Leaks:  0
-Freed:  35
-Reused: 29
-Allocs: 6
-Retain: 5
+Freed:  47
+Reused: 39
+Allocs: 8
+Retain: 7
 
 Unifications: 11
-Conjuncts:    70
-Disjuncts:    33
+Conjuncts:    103
+Disjuncts:    47
 -- out/eval --
 (struct){
   #Value: (int){ |((int){ 0 }, (int){ 1 }) }
   foo: (_|_){
-    // [incomplete] foo: incomplete cause disjunction
-  }
-  bar: (_|_){
-    // [incomplete] bar: incomplete cause disjunction
+    // [incomplete] foo: unresolved disjunction 0 | 1 (type int):
+    //     ./in.cue:4:6
   }
+  bar: (int){ |((int){ 0 }, (int){ 1 }) }
   Foo: (int){ 1 }
   Bar: (int){ 0 }
   cell: (struct){

cue/testdata/cycle/issue429.txtar

@@ -50,14 +50,14 @@ er3: #nonEmptyRange & {
 }
 -- out/eval/stats --
 Leaks:  0
-Freed:  96
-Reused: 89
+Freed:  98
+Reused: 91
 Allocs: 7
-Retain: 8
+Retain: 12
 
 Unifications: 40
-Conjuncts:    150
-Disjuncts:    96
+Conjuncts:    154
+Disjuncts:    101
 -- out/eval --
 Errors:
 er3.min: 2 errors in empty disjunction:
@@ -134,11 +134,9 @@ Result:
   }
   #nonEmptyRange: (#struct){
     min: (_|_){
-      // [incomplete] #nonEmptyRange.min: incomplete cause disjunction
-    }
-    max: (_|_){
-      // [incomplete] #nonEmptyRange.min: incomplete cause disjunction
+      // [cycle] cycle error
     }
+    max: (number){ >1 }
   }
   r1: (#struct){
     min: (int){ 3 }

internal/core/adt/eval.go

@@ -257,19 +257,6 @@ func (c *OpContext) Unify(v *Vertex, state VertexStatus) {
 
 		if !n.done() {
 			switch {
-			case len(n.disjunctions) > 0 && isCyclePlaceholder(v.BaseValue):
-				// We disallow entering computations of disjunctions with
-				// incomplete data.
-				if state == Finalized {
-					b := c.NewErrf("incomplete cause disjunction")
-					b.Code = IncompleteError
-					n.errs = CombineErrors(nil, n.errs, b)
-					v.SetValue(n.ctx, Finalized, b)
-				} else {
-					n.node.UpdateStatus(Partial)
-				}
-				return
-
 			case state < Conjuncts:
 				n.node.UpdateStatus(Partial)
 				return

tools/flow/testdata/template.txtar

@@ -98,31 +98,31 @@ graph TD
 }
 -- out/run/t1/stats --
 Leaks:  0
-Freed:  38
-Reused: 31
+Freed:  41
+Reused: 34
 Allocs: 7
 Retain: 0
 
 Unifications: 24
-Conjuncts:    51
-Disjuncts:    37
+Conjuncts:    64
+Disjuncts:    41
 -- out/run/t2/stats --
 Leaks:  0
-Freed:  38
-Reused: 38
+Freed:  41
+Reused: 41
 Allocs: 0
 Retain: 0
 
 Unifications: 24
-Conjuncts:    55
-Disjuncts:    37
+Conjuncts:    68
+Disjuncts:    41
 -- out/run/stats/totals --
 Leaks:  0
-Freed:  76
-Reused: 69
+Freed:  82
+Reused: 75
 Allocs: 7
 Retain: 0
 
 Unifications: 48
-Conjuncts:    106
-Disjuncts:    74
+Conjuncts:    132
+Disjuncts:    82