diff --git a/cmd/cue/cmd/testdata/script/vet_file.txt b/cmd/cue/cmd/testdata/script/vet_file.txt
index 3797681..d5e5fcd 100644
--- a/cmd/cue/cmd/testdata/script/vet_file.txt
+++ b/cmd/cue/cmd/testdata/script/vet_file.txt
@@ -8,11 +8,13 @@
 translations.hello.lang: incomplete value string
 translations.hello.lang: conflicting values false and string (mismatched types bool and string):
     ./data.yaml:13:11
+    ./vet.cue:3:25
     ./vet.cue:3:31
 -- expect-stderr2 --
 translations.hello.lang: incomplete value string
 translations.hello.lang: conflicting values false and string (mismatched types bool and string):
     ./data.yaml:13:11
+    ./vet.cue:3:25
     ./vet.cue:3:31
 -- vet.cue --
 package foo
diff --git a/cue/testdata/benchmarks/dedupelem.txtar b/cue/testdata/benchmarks/dedupelem.txtar
index ca1ed5b..b83f06c 100644
--- a/cue/testdata/benchmarks/dedupelem.txtar
+++ b/cue/testdata/benchmarks/dedupelem.txtar
@@ -19,7 +19,7 @@
 foo.0.type: conflicting values "int" and "float":
     ./in.cue:3:16
     ./in.cue:5:14
-    ./in.cue:5:30
+    ./in.cue:6:30
 foo.0.type: conflicting values "string" and "float":
     ./in.cue:5:14
     ./in.cue:10:14
@@ -41,7 +41,7 @@
       // foo.0.type: conflicting values "int" and "float":
       //     ./in.cue:3:16
       //     ./in.cue:5:14
-      //     ./in.cue:5:30
+      //     ./in.cue:6:30
       // foo.0.type: conflicting values "string" and "float":
       //     ./in.cue:5:14
       //     ./in.cue:10:14
diff --git a/cue/testdata/comprehensions/issue293.txtar b/cue/testdata/comprehensions/issue293.txtar
index 3bd38ef..30a8166 100644
--- a/cue/testdata/comprehensions/issue293.txtar
+++ b/cue/testdata/comprehensions/issue293.txtar
@@ -27,6 +27,7 @@
 -- out/eval --
 Errors:
 z.x: field `f2` not allowed:
+    ./in.cue:2:2
     ./in.cue:5:12
     ./in.cue:11:4
     ./in.cue:14:3
@@ -46,6 +47,7 @@
       f1: (int){ 99 }
       f2: (_|_){
         // [eval] z.x: field `f2` not allowed:
+        //     ./in.cue:2:2
         //     ./in.cue:5:12
         //     ./in.cue:11:4
         //     ./in.cue:14:3
diff --git "a/cue/testdata/definitions/033_Issue_\043153.txtar" "b/cue/testdata/definitions/033_Issue_\043153.txtar"
index 1eaf9f5..1524dd4 100644
--- "a/cue/testdata/definitions/033_Issue_\043153.txtar"
+++ "b/cue/testdata/definitions/033_Issue_\043153.txtar"
@@ -67,6 +67,7 @@
     ./in.cue:5:10
     ./in.cue:13:1
     ./in.cue:14:18
+    ./in.cue:15:3
     ./in.cue:16:4
 
 Result:
@@ -83,6 +84,7 @@
         //     ./in.cue:5:10
         //     ./in.cue:13:1
         //     ./in.cue:14:18
+        //     ./in.cue:15:3
         //     ./in.cue:16:4
       }
     }
diff --git a/cue/testdata/definitions/037_closing_with_comprehensions.txtar b/cue/testdata/definitions/037_closing_with_comprehensions.txtar
index 289eda3..95024d2 100644
--- a/cue/testdata/definitions/037_closing_with_comprehensions.txtar
+++ b/cue/testdata/definitions/037_closing_with_comprehensions.txtar
@@ -108,9 +108,11 @@
     ./in.cue:1:5
     ./in.cue:27:5
     ./in.cue:27:10
+    ./in.cue:28:2
     ./in.cue:29:3
 a: field `f3` not allowed:
     ./in.cue:1:5
+    ./in.cue:3:1
     ./in.cue:4:5
     ./in.cue:4:11
 
@@ -139,6 +141,7 @@
       //     ./in.cue:1:5
       //     ./in.cue:27:5
       //     ./in.cue:27:10
+      //     ./in.cue:28:2
       //     ./in.cue:29:3
     }
   }
@@ -149,6 +152,7 @@
     f3: (_|_){
       // [eval] a: field `f3` not allowed:
       //     ./in.cue:1:5
+      //     ./in.cue:3:1
       //     ./in.cue:4:5
       //     ./in.cue:4:11
     }
diff --git a/cue/testdata/resolve/029_non-closed_definition_carries_over_closedness_to_enclosed_template.txtar b/cue/testdata/resolve/029_non-closed_definition_carries_over_closedness_to_enclosed_template.txtar
index f94d398..c184206 100644
--- a/cue/testdata/resolve/029_non-closed_definition_carries_over_closedness_to_enclosed_template.txtar
+++ b/cue/testdata/resolve/029_non-closed_definition_carries_over_closedness_to_enclosed_template.txtar
@@ -114,6 +114,7 @@
     ./in.cue:10:4
     ./in.cue:11:6
 c.w.0: field `d` not allowed:
+    ./in.cue:14:12
     ./in.cue:14:13
     ./in.cue:16:4
     ./in.cue:17:7
@@ -148,6 +149,7 @@
       //     ./in.cue:11:6
       c: (_|_){
         // [eval] b.w: field `c` not allowed:
+        //     ./in.cue:8:12
         //     ./in.cue:8:23
         //     ./in.cue:10:4
         //     ./in.cue:11:6
@@ -165,6 +167,7 @@
         // [eval]
         d: (_|_){
           // [eval] c.w.0: field `d` not allowed:
+          //     ./in.cue:14:12
           //     ./in.cue:14:13
           //     ./in.cue:16:4
           //     ./in.cue:17:7
diff --git a/internal/core/adt/closed.go b/internal/core/adt/closed.go
index 327d7a5..6e978f3 100644
--- a/internal/core/adt/closed.go
+++ b/internal/core/adt/closed.go
@@ -91,9 +91,9 @@
 
 // TODO: merge with closeInfo: this is a leftover of the refactoring.
 type CloseInfo struct {
-	IsClosed bool
-
 	*closeInfo
+
+	IsClosed bool
 }
 
 // TODO(perf): remove: error positions should always be computed on demand
@@ -141,6 +141,22 @@
 	return c
 }
 
+// SpawnSpan is used to track that a value is introduced by a comprehension
+// or constraint. Definition and embedding spans are introduced with SpawnRef
+// and SpawnEmbed, respectively.
+func (c CloseInfo) SpawnSpan(x Node, t SpanType) CloseInfo {
+	var span SpanType
+	if c.closeInfo != nil {
+		span = c.span
+	}
+	c.closeInfo = &closeInfo{
+		parent:   c.closeInfo,
+		location: x,
+		span:     span | t,
+	}
+	return c
+}
+
 func (c CloseInfo) SpawnRef(arc *Vertex, isDef bool, x Expr) CloseInfo {
 	var span SpanType
 	if c.closeInfo != nil {
@@ -153,6 +169,7 @@
 	}
 	if isDef {
 		c.mode = closeDef
+		c.closeInfo.span |= DefinitionSpan
 	}
 	return c
 }
@@ -187,12 +204,9 @@
 	// EmbeddingSpan means that this value was embedded at some point and should
 	// not be included as a possible root node in the todo field of OpContext.
 	EmbeddingSpan SpanType = 1 << iota
-
-	// TODO:
-	// from comprehension
-	// from template.
-	// from definition
-
+	ConstraintSpan
+	ComprehensionSpan
+	DefinitionSpan
 )
 
 type closeInfo struct {
diff --git a/internal/core/adt/eval.go b/internal/core/adt/eval.go
index 54058de..766f339 100644
--- a/internal/core/adt/eval.go
+++ b/internal/core/adt/eval.go
@@ -1787,8 +1787,12 @@
 			continue
 		}
 
+		if len(sa) == 0 {
+			continue
+		}
+		id := d.id.SpawnSpan(d.yield, ComprehensionSpan)
 		for _, st := range sa {
-			n.addStruct(st.env, st.s, d.id)
+			n.addStruct(st.env, st.s, id)
 		}
 	}
 
diff --git a/internal/core/adt/expr.go b/internal/core/adt/expr.go
index 2a6e1aa..ba5aabd 100644
--- a/internal/core/adt/expr.go
+++ b/internal/core/adt/expr.go
@@ -127,6 +127,7 @@
 			if x.Value == nil {
 				o.IsOpen = true
 				o.types |= IsOpen
+				// TODO(perf): encode more efficiently.
 				expr = &Top{}
 			} else {
 				o.types |= HasAdditional
diff --git a/internal/core/adt/optional.go b/internal/core/adt/optional.go
index 504d0f6..c648431 100644
--- a/internal/core/adt/optional.go
+++ b/internal/core/adt/optional.go
@@ -40,22 +40,26 @@
 		return
 	}
 
-	bulkEnv := *env
-	bulkEnv.DynamicLabel = arc.Label
-	bulkEnv.Deref = nil
-	bulkEnv.Cycles = nil
+	if len(o.Bulk) > 0 {
+		bulkEnv := *env
+		bulkEnv.DynamicLabel = arc.Label
+		bulkEnv.Deref = nil
+		bulkEnv.Cycles = nil
 
-	// match bulk optional fields / pattern properties
-	for _, b := range o.Bulk {
-		// if matched && f.additional {
-		// 	continue
-		// }
-		if matchBulk(c, env, b, arc.Label) {
-			matched = true
-			arc.AddConjunct(MakeConjunct(&bulkEnv, b, closeInfo))
+		// match bulk optional fields / pattern properties
+		for _, b := range o.Bulk {
+			// if matched && f.additional {
+			// 	continue
+			// }
+			if matchBulk(c, env, b, arc.Label) {
+				matched = true
+				info := closeInfo.SpawnSpan(b.Value, ConstraintSpan)
+				arc.AddConjunct(MakeConjunct(&bulkEnv, b, info))
+			}
 		}
 	}
-	if matched {
+
+	if matched || len(o.Additional) == 0 {
 		return
 	}
 
@@ -65,7 +69,11 @@
 
 	// match others
 	for _, x := range o.Additional {
-		arc.AddConjunct(MakeConjunct(&addEnv, x, closeInfo))
+		info := closeInfo
+		if _, ok := x.(*Top); !ok {
+			info = info.SpawnSpan(x, ConstraintSpan)
+		}
+		arc.AddConjunct(MakeConjunct(&addEnv, x, info))
 	}
 }