internal/core/eval: rewrite of closedness algorithm

Spec did not change, but simplified algorithm.
Fixes many bugs.

This also adds a new compaction algorithm. This will be
enabled in a follow-up CL.

Also:
- "not allowed" failure is now registered with child. This
allows multiple failures to be recorded naturally, and
also retains more of the correct structure. But more
importantly, it prevents descending into the substructure,
preventing spurious errors.
- Position information has changed slightly, mostly for
the better.

This introduces a regression on trim. See tools/trim/trim_test.go

Fixes #271
Fixes #320
Fixes #370
Fixes #471
Fixes #476
Fixes #483
Fixes #490
Fixes #491
Fixes #493
Fixes #494
Fixes #496
Fixes #497

Change-Id: Ia90ebbbafd8cfc768188d33f109a2e33a4cee922
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7002
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

cmd/cue/cmd/testdata/script/cmd_closed.txt

@@ -0,0 +1,20 @@
+cue cmd run
+
+-- task.cue --
+package ci
+
+// Must have
+// - indirection through definition
+// - unification of two list elements
+// - one of those elements must be _
+// - Must use merge and unify tool file
+
+workflows: #Workflow
+
+#Workflow: ["a"] & [_]
+
+-- task_tool.cue --
+package ci
+
+command: run: {
+}

cmd/cue/cmd/testdata/script/issue476.txt

@@ -0,0 +1,38 @@
+cue cmd dostuffloop
+cmp stdout expect-stdout
+
+-- x_tool.cue --
+package x
+
+import (
+        "tool/cli"
+        "encoding/yaml"
+)
+
+command: dostuff: {
+        write: cli.Print & {
+                text: "yaml is " + yaml.Marshal(w)
+        }
+}
+
+command: dostuffloop: {
+        for w in l {
+                write: cli.Print & {
+                        text: "yaml is " + yaml.Marshal(w)
+                }
+        }
+}
+-- y.cue --
+package x
+
+#Workflow: {
+  #: "working-directory": string
+}
+
+l: [w]
+w: #Workflow & {
+}
+
+-- expect-stdout --
+yaml is {}
+

cmd/cue/cmd/testdata/script/trim.txt

@@ -44,6 +44,7 @@ foo: multipath: {
 	}
 
 	t: u: {
+		x: 5
 	}
 }
 

cue/testdata/builtins/closed.txtar

@@ -0,0 +1,57 @@
+-- in.cue --
+a: close({
+    a: b: int
+})
+
+b: a & { x: int } // err
+c: a & { a: c: int } // okay (non-recursive close)
+
+-- out/eval --
+Errors:
+b: field `x` not allowed:
+    ./in.cue:1:10
+    ./in.cue:5:10
+
+Result:
+(_|_){
+  // [eval]
+  a: (#struct){
+    a: (#struct){
+      b: (int){ int }
+    }
+  }
+  b: (_|_){
+    // [eval]
+    a: (#struct){
+      b: (int){ int }
+    }
+    x: (_|_){
+      // [eval] b: field `x` not allowed:
+      //     ./in.cue:1:10
+      //     ./in.cue:5:10
+    }
+  }
+  c: (#struct){
+    a: (#struct){
+      b: (int){ int }
+      c: (int){ int }
+    }
+  }
+}
+-- out/compile --
+--- in.cue
+{
+  a: close({
+    a: {
+      b: int
+    }
+  })
+  b: (〈0;a〉 & {
+    x: int
+  })
+  c: (〈0;a〉 & {
+    a: {
+      c: int
+    }
+  })
+}

cue/testdata/builtins/issue490.txtar

@@ -0,0 +1,44 @@
+-- test.cue --
+A: close({
+	a: 1
+	b: 2
+})
+
+B: A & {
+	c: 3
+}
+-- out/eval --
+Errors:
+B: field `c` not allowed:
+    ./test.cue:1:10
+    ./test.cue:7:2
+
+Result:
+(_|_){
+  // [eval]
+  A: (#struct){
+    a: (int){ 1 }
+    b: (int){ 2 }
+  }
+  B: (_|_){
+    // [eval]
+    a: (int){ 1 }
+    b: (int){ 2 }
+    c: (_|_){
+      // [eval] B: field `c` not allowed:
+      //     ./test.cue:1:10
+      //     ./test.cue:7:2
+    }
+  }
+}
+-- out/compile --
+--- test.cue
+{
+  A: close({
+    a: 1
+    b: 2
+  })
+  B: (〈0;A〉 & {
+    c: 3
+  })
+}

cue/testdata/definitions/026_combined_definitions.txtar

@@ -119,13 +119,13 @@ d1: #D1 & {
 -- out/eval --
 Errors:
 #D4.env: field `b` not allowed:
+    ./in.cue:26:7
     ./in.cue:27:7
-    ./in.cue:30:1
     ./in.cue:30:6
 d1.env: field `c` not allowed:
-    ./in.cue:2:1
     ./in.cue:3:7
     ./in.cue:4:7
+    ./in.cue:9:5
     ./in.cue:9:17
 
 Result:
@@ -144,14 +144,16 @@ Result:
   d1: (_|_){
     // [eval]
     env: (_|_){
-      // [eval] d1.env: field `c` not allowed:
-      //     ./in.cue:2:1
-      //     ./in.cue:3:7
-      //     ./in.cue:4:7
-      //     ./in.cue:9:17
+      // [eval]
       a: (string){ "A" }
       b: (string){ "B" }
-      c: (string){ "C" }
+      c: (_|_){
+        // [eval] d1.env: field `c` not allowed:
+        //     ./in.cue:3:7
+        //     ./in.cue:4:7
+        //     ./in.cue:9:5
+        //     ./in.cue:9:17
+      }
     }
     #def: (#struct){
       a: (string){ "A" }
@@ -171,12 +173,14 @@ Result:
   #D4: (_|_){
     // [eval]
     env: (_|_){
-      // [eval] #D4.env: field `b` not allowed:
-      //     ./in.cue:27:7
-      //     ./in.cue:30:1
-      //     ./in.cue:30:6
+      // [eval]
       a: (int){ int }
-      b: (int){ int }
+      b: (_|_){
+        // [eval] #D4.env: field `b` not allowed:
+        //     ./in.cue:26:7
+        //     ./in.cue:27:7
+        //     ./in.cue:30:6
+      }
     }
   }
   #DC: (#struct){

cue/testdata/definitions/032_definitions_with_embedding.txtar

@@ -82,9 +82,10 @@
 -- out/eval --
 Errors:
 #e1.a: field `d` not allowed:
-    ./in.cue:1:1
     ./in.cue:2:5
+    ./in.cue:6:2
     ./in.cue:7:5
+    ./in.cue:12:6
     ./in.cue:12:15
 
 Result:
@@ -105,14 +106,17 @@ Result:
   #e1: (_|_){
     // [eval]
     a: (_|_){
-      // [eval] #e1.a: field `d` not allowed:
-      //     ./in.cue:1:1
-      //     ./in.cue:2:5
-      //     ./in.cue:7:5
-      //     ./in.cue:12:15
+      // [eval]
       b: (int){ int }
       c: (int){ int }
-      d: (int){ 4 }
+      d: (_|_){
+        // [eval] #e1.a: field `d` not allowed:
+        //     ./in.cue:2:5
+        //     ./in.cue:6:2
+        //     ./in.cue:7:5
+        //     ./in.cue:12:6
+        //     ./in.cue:12:15
+      }
     }
     b: (int){ 3 }
   }

cue/testdata/definitions/033_Issue_#153.txtar

@@ -63,24 +63,26 @@ Junk: {
 -- out/eval --
 Errors:
 listOfCloseds.0: field `b` not allowed:
-    ./in.cue:5:1
+    ./in.cue:2:21
     ./in.cue:5:10
-    ./in.cue:14:18
-    ./in.cue:15:20
+    ./in.cue:13:1
+    ./in.cue:16:4
 
 Result:
 (_|_){
   // [eval]
   listOfCloseds: (_|_){
     // [eval]
     0: (_|_){
-      // [eval] listOfCloseds.0: field `b` not allowed:
-      //     ./in.cue:5:1
-      //     ./in.cue:5:10
-      //     ./in.cue:14:18
-      //     ./in.cue:15:20
+      // [eval]
       a: (int){ |(*(int){ 0 }, (int){ int }) }
-      b: (int){ 2 }
+      b: (_|_){
+        // [eval] listOfCloseds.0: field `b` not allowed:
+        //     ./in.cue:2:21
+        //     ./in.cue:5:10
+        //     ./in.cue:13:1
+        //     ./in.cue:16:4
+      }
     }
   }
   Foo: (struct){

cue/testdata/definitions/037_closing_with_comprehensions.txtar

@@ -106,14 +106,13 @@ a: _|_ // field "f3" not allowed in closed struct
 Errors:
 #D: cannot mix bulk optional fields with dynamic fields, embeddings, or comprehensions within the same struct
 #E: field `f3` not allowed:
-    ./in.cue:1:1
     ./in.cue:1:5
-    ./in.cue:27:10
-    ./in.cue:28:24
+    ./in.cue:27:5
+    ./in.cue:29:3
 a: field `f3` not allowed:
-    ./in.cue:1:1
     ./in.cue:1:5
-    ./in.cue:4:10
+    ./in.cue:4:5
+    ./in.cue:4:11
 
 Result:
 (_|_){
@@ -133,22 +132,25 @@ Result:
     f1: (int){ int }
   }
   #E: (_|_){
-    // [eval] #E: field `f3` not allowed:
-    //     ./in.cue:1:1
-    //     ./in.cue:1:5
-    //     ./in.cue:27:10
-    //     ./in.cue:28:24
+    // [eval]
     f1: (int){ int }
     f2: (int){ int }
-    f3: (int){ int }
+    f3: (_|_){
+      // [eval] #E: field `f3` not allowed:
+      //     ./in.cue:1:5
+      //     ./in.cue:27:5
+      //     ./in.cue:29:3
+    }
   }
   a: (_|_){
-    // [eval] a: field `f3` not allowed:
-    //     ./in.cue:1:1
-    //     ./in.cue:1:5
-    //     ./in.cue:4:10
+    // [eval]
     f1: (int){ int }
     f2: (int){ int }
-    f3: (int){ int }
+    f3: (_|_){
+      // [eval] a: field `f3` not allowed:
+      //     ./in.cue:1:5
+      //     ./in.cue:4:5
+      //     ./in.cue:4:11
+    }
   }
 }