internal/core/adt: track more incomplete errors

This was sometimes lost in computation,
for instance across package boundaries.

This results in less nice errors for certain cycle cases.
This should be handled in an evaluator rework.

Fixes #854

Change-Id: Ieb927dbb8d11d2ad2651b85a375d11913a8612b2
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9181
Reviewed-by: Marcel van Lohuizen <[email protected]>

cue/testdata/cycle/compbottomnofinal.txtar

@@ -370,14 +370,8 @@ medium.p1.#Y: cycle: field port was added after an if clause evaluated it
 medium.p2.#Y: cycle: field port was added after an if clause evaluated it
 medium.p3.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 medium.p4.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
-medium.p5.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
-medium.p6.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 minimal.b: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 small.p1.#Y: cycle: field port was added after an if clause evaluated it
-small.p2.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
-small.p2.#Y: cycle: field port was added after an if clause evaluated it
-small.p2.#X: cannot use "" (type string) as int in argument 1 to strconv.FormatInt:
-    ./in.cue:50:7
 
 Result:
 (_|_){
@@ -404,17 +398,13 @@ Result:
         port: (string){ "" }
       }
     }
-    p2: (_|_){
-      // [eval]
-      #X: (_|_){
-        // [eval] small.p2.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
-        port: (_|_){
-          // [eval] small.p2.#X: cannot use "" (type string) as int in argument 1 to strconv.FormatInt:
-          //     ./in.cue:50:7
-        }
+    p2: (struct){
+      #X: (#struct){
+        port: (string){ "" }
       }
       #Y: (_|_){
-        // [eval] small.p2.#Y: cycle: field port was added after an if clause evaluated it
+        // [incomplete] small.p2.#Y: undefined field port:
+        //     ./in.cue:50:50
         port: (string){ "" }
       }
     }
@@ -476,28 +466,28 @@ Result:
         port: (string){ "" }
       }
     }
-    p5: (_|_){
-      // [eval]
-      #X: (_|_){
-        // [eval] medium.p5.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
+    p5: (struct){
+      #X: (#struct){
         port: (string){ "" }
       }
       #Y: (_|_){
-        // [eval] medium.p5.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
+        // [incomplete] medium.p5.#Y: undefined field port:
+        //     ./in.cue:158:56
+        port: (string){ "" }
       }
       Y: (struct){
       }
     }
-    p6: (_|_){
-      // [eval]
-      #X: (_|_){
-        // [eval] medium.p6.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
+    p6: (struct){
+      #X: (#struct){
         port: (string){ "" }
       }
       Y: (struct){
       }
       #Y: (_|_){
-        // [eval] medium.p6.#X: cycle: new field port inserted by if clause that was previously evaluated by another if clause
+        // [incomplete] medium.p6.#Y: undefined field port:
+        //     ./in.cue:186:56
+        port: (string){ "" }
       }
     }
   }

cue/testdata/export/issue854.txtar

@@ -0,0 +1,32 @@
+-- cue.mod/module.cue --
+module: "mod.com"
+-- a.cue --
+package a
+
+import "mod.com/b"
+
+theb: b.name
+-- b/b.cue --
+package b
+
+import "mod.com/c"
+
+b: c.c & {
+	other: "name"
+}
+
+name: b.other
+-- c/c.cue --
+package c
+-- out/compile --
+--- a.cue
+{
+  theb: 〈import;"mod.com/b"〉.name
+}
+-- out/eval --
+(struct){
+  theb: (_|_){
+    // [incomplete] b: undefined field c:
+    //     ./b/b.cue:5:6
+  }
+}

internal/core/adt/expr.go

@@ -864,6 +864,12 @@ func (x *SelectorExpr) resolve(c *OpContext, state VertexStatus) *Vertex {
 	if n == emptyNode {
 		return n
 	}
+	if n.status == Partial {
+		if b := n.state.incompleteErrors(); b != nil && b.Code < CycleError {
+			n.BaseValue = b
+			return n
+		}
+	}
 	return c.lookup(n, x.Src.Sel.Pos(), x.Sel, state)
 }
 
@@ -891,6 +897,12 @@ func (x *IndexExpr) resolve(ctx *OpContext, state VertexStatus) *Vertex {
 	if n == emptyNode {
 		return n
 	}
+	if n.status == Partial {
+		if b := n.state.incompleteErrors(); b != nil && b.Code < CycleError {
+			n.BaseValue = b
+			return n
+		}
+	}
 	f := ctx.Label(x.Index, i)
 	return ctx.lookup(n, x.Src.Index.Pos(), f, state)
 }