internal/core/adt: fix missing field error message

It used to be that a "NotPresent" arc was indicative
of a cyclic evaluation. Now it is just not present.

Adjust the error message accordingly.

Issue #3060
Issue #2884

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: If9207745dc8daced4bc01818a88ce5a21d049eab
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1194078
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

Author: mpvl

cue/testdata/cycle/compbottomnofinal.txtar

@@ -484,7 +484,7 @@ Disjuncts:    215
         host: (string){ "mod.test" }
       }
       X: (_|_){
-        // [incomplete] large.p1.X: cyclic reference to field port:
+        // [incomplete] large.p1.X: undefined field: port:
         //     ./in.cue:199:33
       }
       #X: (_|_){
@@ -494,13 +494,13 @@ Disjuncts:    215
         host: (string){ "mod.test" }
       }
       #Y: (_|_){
-        // [incomplete] large.p1.X: cyclic reference to field port:
+        // [incomplete] large.p1.X: undefined field: port:
         //     ./in.cue:199:33
       }
     }
     p2: (struct){
       X: (_|_){
-        // [incomplete] large.p2.X: cyclic reference to field port:
+        // [incomplete] large.p2.X: undefined field: port:
         //     ./in.cue:235:33
       }
       Y: (struct){
@@ -520,7 +520,7 @@ Disjuncts:    215
     }
     p3: (struct){
       X: (_|_){
-        // [incomplete] large.p3.X: cyclic reference to field port:
+        // [incomplete] large.p3.X: undefined field: port:
         //     ./in.cue:276:33
       }
       #X: (_|_){
@@ -540,7 +540,7 @@ Disjuncts:    215
     }
     p4: (struct){
       X: (_|_){
-        // [incomplete] large.p4.X: cyclic reference to field port:
+        // [incomplete] large.p4.X: undefined field: port:
         //     ./in.cue:317:33
       }
       #X: (_|_){
@@ -845,7 +845,7 @@ diff old new
 +        host: (string){ "mod.test" }
 +      }
 +      X: (_|_){
-+        // [incomplete] large.p1.X: cyclic reference to field port:
++        // [incomplete] large.p1.X: undefined field: port:
 +        //     ./in.cue:199:33
 +      }
 +      #X: (_|_){
@@ -855,13 +855,13 @@ diff old new
 +        host: (string){ "mod.test" }
 +      }
 +      #Y: (_|_){
-+        // [incomplete] large.p1.X: cyclic reference to field port:
++        // [incomplete] large.p1.X: undefined field: port:
 +        //     ./in.cue:199:33
 +      }
 +    }
 +    p2: (struct){
 +      X: (_|_){
-+        // [incomplete] large.p2.X: cyclic reference to field port:
++        // [incomplete] large.p2.X: undefined field: port:
 +        //     ./in.cue:235:33
 +      }
 +      Y: (struct){
@@ -881,7 +881,7 @@ diff old new
 +    }
 +    p3: (struct){
 +      X: (_|_){
-+        // [incomplete] large.p3.X: cyclic reference to field port:
++        // [incomplete] large.p3.X: undefined field: port:
 +        //     ./in.cue:276:33
 +      }
 +      #X: (_|_){
@@ -901,7 +901,7 @@ diff old new
 +    }
 +    p4: (struct){
 +      X: (_|_){
-+        // [incomplete] large.p4.X: cyclic reference to field port:
++        // [incomplete] large.p4.X: undefined field: port:
 +        //     ./in.cue:317:33
 +      }
 +      #X: (_|_){

cue/testdata/cycle/comprehension.txtar

@@ -666,12 +666,12 @@ Result:
       }
     }
     fail: (_|_){
-      // [incomplete] selfReferential.fail.b: cyclic reference to field x:
+      // [incomplete] selfReferential.fail.b: undefined field: x:
       //     ./in.cue:300:7
       a: (struct){
       }
       b: (_|_){
-        // [incomplete] selfReferential.fail.b: cyclic reference to field x:
+        // [incomplete] selfReferential.fail.b: undefined field: x:
         //     ./in.cue:300:7
       }
     }
@@ -952,7 +952,7 @@ diff old new
          }
        }
      }
-@@ -127,208 +181,269 @@
+@@ -127,116 +181,165 @@
      insertionError: (_|_){
        // [eval]
        A: (_|_){
@@ -1227,16 +1227,7 @@ diff old new
          }
        }
      }
-     fail: (_|_){
--      // [incomplete] selfReferential.fail.b: undefined field: x:
-+      // [incomplete] selfReferential.fail.b: cyclic reference to field x:
-       //     ./in.cue:300:7
-       a: (struct){
-       }
-       b: (_|_){
--        // [incomplete] selfReferential.fail.b: undefined field: x:
-+        // [incomplete] selfReferential.fail.b: cyclic reference to field x:
-         //     ./in.cue:300:7
+@@ -251,84 +354,96 @@
        }
      }
    }

cue/types_test.go

@@ -806,17 +806,13 @@ func TestFields(t *testing.T) {
 		if step1.value > 100 {
 		}`,
 		err: "undefined field: value",
-
-		todoV3: true,
 	}, {
 		opts: []Option{Concrete(true)},
 		value: `
 		step1: {}
 		if step1.value > 100 {
 		}`,
 		err: "undefined field: value",
-
-		todoV3: true,
 	}, {
 		value: `{a!: 1, b?: 2, c: 3}`,
 		err:   "a: field is required but not present",
@@ -835,10 +831,6 @@ func TestFields(t *testing.T) {
 	}}
 	for _, tc := range testCases {
 		runMatrix(t, tc.value, func(t *testing.T, cfg *evalConfig) {
-			if tc.todoV3 {
-				TODO_V3(t, cfg)
-			}
-
 			obj := cfg.getValue(t, tc.value)
 
 			iter, err := obj.Fields(tc.opts...)

internal/core/adt/unify.go

@@ -710,7 +710,7 @@ func (v *Vertex) lookup(c *OpContext, pos token.Pos, f Feature, flags combinedFl
 		return nil
 
 	case ArcNotPresent:
-		v.reportFieldCycleError(c, pos, f)
+		v.reportFieldIndexError(c, pos, f)
 		return nil
 
 	case ArcPending: