diff --git a/cue/testdata/cycle/builtins.txtar b/cue/testdata/cycle/builtins.txtar
index f0c429955..7b494f211 100644
--- a/cue/testdata/cycle/builtins.txtar
+++ b/cue/testdata/cycle/builtins.txtar
@@ -134,8 +134,6 @@ issue3633: final: {
 	#s: matchN(1, [matchN(1, [{a!: _}])])
 }
 -- cycle.cue --
-import "encoding/yaml"
-
 noCycle: t1: {
 	_s
 	_s: {
@@ -169,6 +167,9 @@ issue3649: cycle: t1: {
 		a: matchN(1, [#c])
 	}
 }
+-- yamlcycle.cue --
+import "encoding/yaml"
+
 yamlNoCycle: {
 	// the validator is invoked recursively and also unifies with a concrete
 	// value. This should nonetheless not result in a cycle error.
@@ -189,34 +190,60 @@ selfCycle: t2: {
 	c: matchN(1, [{d: c}])
 	c: {}
 }
-// TODO: fix hang
-// selfCycle: yamlVal: t1: {
-// 	x: y: yaml.Validate(x)
-// 	x: y: "{}"
-// }
-// selfCycle: yamlVal: t1: {
-// 	x: y: yaml.Validate(x)
-// 	x: y: "{}"
-// }
-// selfCycle: yamlFun: t1:{
-// 	x: y?: yaml.Validate("{}", x)
-// }
-// selfCycle: yamlFun: t2: {
-// 	z: x & __no_sharing
-// 	z: y: "{}"
-// 	x: y: yaml.Validate("{}", x)
-// }
+selfCycle: yamlVal: t1: {
+	x: y: yaml.Validate(x)
+	x: y: "{}"
+}
+selfCycle: yamlVal: t2: {
+	// Duplicating validators can cause some tricky code paths, like finalizing
+	// a node while still in the middle of validation.
+	x: y: yaml.Validate(x)
+	x: y: "{}"
+	x: y: yaml.Validate(x)
+	x: y: "{}"
+}
+selfCycle: yamlFun: t1:{
+	x: y?: yaml.Validate("{}", x)
+}
+selfCycle: yamlFun: t2: {
+	z: x & __no_sharing
+	z: y: "{}"
+	x: y: yaml.Validate("{}", x)
+}
+selfCycle: yamlValidatePartial: {
+	x: y: yaml.ValidatePartial(x)
+	x: y: "{}"
+}
+-- jsoncycle.cue --
+import "encoding/json"
+
+jsonCycle: t1: {
+	x: y: json.Validate(x)
+	x: y: "{}"
+}
+-- listmatchncycle.cue --
+import "list"
+
+listMatchN: structCycle: {
+	x: y: list.MatchN(1, x)
+	x: y: [{}]
+}
+listMatchN: ok: {
+	x: y?: list.MatchN(1, x)
+    z: x
+	z: y: [{}]
+}
 -- todo/p1 --
 issue3443.noCycle: fix hang
 -- out/evalalpha/stats --
-Leaks:  351
+Leaks:  410
 Freed:  17
 Reused: 17
-Allocs: 351
+Allocs: 410
 Retain: 0
 
-Unifications: 310
-Conjuncts:    1216
+Unifications: 368
+Conjuncts:    1497
 Disjuncts:    28
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
@@ -224,66 +251,57 @@ diff old new
 +++ new
 @@ -1,9 +1,9 @@
 -Leaks:  23
--Freed:  357
--Reused: 345
+-Freed:  414
+-Reused: 402
 -Allocs: 35
--Retain: 94
-+Leaks:  351
+-Retain: 95
++Leaks:  410
 +Freed:  17
 +Reused: 17
-+Allocs: 351
++Allocs: 410
 +Retain: 0
  
--Unifications: 352
--Conjuncts:    625
--Disjuncts:    441
-+Unifications: 310
-+Conjuncts:    1216
+-Unifications: 409
+-Conjuncts:    764
+-Disjuncts:    501
++Unifications: 368
++Conjuncts:    1497
 +Disjuncts:    28
 -- out/eval/stats --
 Leaks:  23
-Freed:  357
-Reused: 345
+Freed:  414
+Reused: 402
 Allocs: 35
-Retain: 94
+Retain: 95
 
-Unifications: 352
-Conjuncts:    625
-Disjuncts:    441
+Unifications: 409
+Conjuncts:    764
+Disjuncts:    501
 -- out/evalalpha --
 Errors:
 noCycle.t1.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
 noCycle.t1.#x.#x: structural cycle:
-    ./cycle.cue:6:7
+    ./cycle.cue:4:7
 noCycle.t1._s.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
 issue3649.cycle.t1.data.a: invalid value {b:"foo"} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:33:6
-    ./cycle.cue:30:11
-    ./cycle.cue:33:13
+    ./cycle.cue:31:6
+    ./cycle.cue:28:11
+    ./cycle.cue:31:13
 issue3649.cycle.t1.data.a.a: structural cycle:
-    ./cycle.cue:33:6
-selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:48:5
-selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:47:20
-    ./cycle.cue:48:8
-selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:47:20
-    ./cycle.cue:48:8
-selfCycle.t1.c.d.d.d: structural cycle:
-    ./cycle.cue:47:5
+    ./cycle.cue:31:6
+jsonCycle.t1.x.y: invalid value "{}" (does not satisfy encoding/json.Validate): error in call to encoding/json.Validate: structural cycle:
+    ./jsoncycle.cue:4:8
+    ./jsoncycle.cue:5:8
+listMatchN.structCycle.x.y: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1:
+    ./listmatchncycle.cue:4:8
+    ./listmatchncycle.cue:4:20
+    ./listmatchncycle.cue:5:8
 issue3443.matchIf.#S: cannot call non-function matchIf (type struct):
     ./matchn.cue:16:7
 issue3443.cycle1.cycle.s: invalid value {n:{n:_}} (does not satisfy matchN): 0 matched, expected 1:
@@ -314,6 +332,37 @@ issue3443.cycle2.fail.#S.n.n: invalid value {n:{n:{n:_}}} (does not satisfy matc
     ./matchn.cue:55:43
 issue3443.cycle2.fail.#S.n.n.n: structural cycle:
     ./matchn.cue:55:13
+selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:15:5
+selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:14:20
+    ./yamlcycle.cue:15:8
+selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:14:20
+    ./yamlcycle.cue:15:8
+selfCycle.t1.c.d.d.d: structural cycle:
+    ./yamlcycle.cue:14:5
+selfCycle.yamlVal.t1.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
+    ./yamlcycle.cue:24:8
+    ./yamlcycle.cue:25:8
+selfCycle.yamlVal.t2.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
+    ./yamlcycle.cue:30:8
+    ./yamlcycle.cue:31:8
+    ./yamlcycle.cue:32:8
+    ./yamlcycle.cue:33:8
+selfCycle.yamlFun.t2.x.y: error in call to encoding/yaml.Validate: structural cycle:
+    ./yamlcycle.cue:41:8
+selfCycle.yamlFun.t2.z.y: error in call to encoding/yaml.Validate: structural cycle:
+    ./yamlcycle.cue:41:8
+selfCycle.yamlValidatePartial.x.y: invalid value "{}" (does not satisfy encoding/yaml.ValidatePartial): error in call to encoding/yaml.ValidatePartial: structural cycle:
+    ./yamlcycle.cue:44:8
+    ./yamlcycle.cue:45:8
 
 Result:
 (_|_){
@@ -326,18 +375,18 @@ Result:
         // [eval]
         #x: (_|_){
           // [eval] noCycle.t1._s.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-          //     ./cycle.cue:6:7
-          //     ./cycle.cue:6:14
-          //     ./cycle.cue:7:13
+          //     ./cycle.cue:4:7
+          //     ./cycle.cue:4:14
+          //     ./cycle.cue:5:13
         }
       }
       #x: (_|_){
         // [eval] noCycle.t1.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:6:7
-        //     ./cycle.cue:6:14
-        //     ./cycle.cue:7:13
+        //     ./cycle.cue:4:7
+        //     ./cycle.cue:4:14
+        //     ./cycle.cue:5:13
         // noCycle.t1.#x.#x: structural cycle:
-        //     ./cycle.cue:6:7
+        //     ./cycle.cue:4:7
       }
     }
   }
@@ -391,11 +440,11 @@ Result:
           // [eval]
           a: (_|_){
             // [eval] issue3649.cycle.t1.data.a: invalid value {b:"foo"} (does not satisfy matchN): 0 matched, expected 1:
-            //     ./cycle.cue:33:6
-            //     ./cycle.cue:30:11
-            //     ./cycle.cue:33:13
+            //     ./cycle.cue:31:6
+            //     ./cycle.cue:28:11
+            //     ./cycle.cue:31:13
             // issue3649.cycle.t1.data.a.a: structural cycle:
-            //     ./cycle.cue:33:6
+            //     ./cycle.cue:31:6
             b: (string){ "foo" }
           }
           b: (string){ string }
@@ -410,46 +459,6 @@ Result:
       }
     }
   }
-  yamlNoCycle: (struct){
-    #c: (#struct){
-      b?: (string){ string }
-      a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
-    }
-    data: (#struct){
-      a: (string){ "{a: \"b: foo\"}" }
-      b?: (string){ string }
-    }
-  }
-  selfCycle: (_|_){
-    // [eval]
-    t1: (_|_){
-      // [eval]
-      c: (_|_){
-        // [eval] selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:48:5
-        // selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:47:20
-        //     ./cycle.cue:48:8
-        // selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:47:20
-        //     ./cycle.cue:48:8
-        // selfCycle.t1.c.d.d.d: structural cycle:
-        //     ./cycle.cue:47:5
-        d: (struct){
-        }
-      }
-    }
-    t2: (struct){
-      c: (struct){
-      }
-    }
-  }
   builtinCyclePerm0: (struct){
     X: (string){ "mod.test" }
     Y: (struct){
@@ -504,6 +513,48 @@ Result:
       host: (string){ "mod.test" }
     }
   }
+  jsonCycle: (_|_){
+    // [structural cycle]
+    t1: (_|_){
+      // [structural cycle]
+      x: (_|_){
+        // [structural cycle]
+        y: (_|_){
+          // [structural cycle] jsonCycle.t1.x.y: invalid value "{}" (does not satisfy encoding/json.Validate): error in call to encoding/json.Validate: structural cycle:
+          //     ./jsoncycle.cue:4:8
+          //     ./jsoncycle.cue:5:8
+        }
+      }
+    }
+  }
+  listMatchN: (_|_){
+    // [eval]
+    structCycle: (_|_){
+      // [eval]
+      x: (_|_){
+        // [eval]
+        y: (_|_){
+          // [eval] listMatchN.structCycle.x.y: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1:
+          //     ./listmatchncycle.cue:4:8
+          //     ./listmatchncycle.cue:4:20
+          //     ./listmatchncycle.cue:5:8
+          0: (struct){
+          }
+        }
+      }
+    }
+    ok: (struct){
+      x: (struct){
+        y?: (list){ list.MatchN(1, listMatchN.ok.x) }
+      }
+      z: (struct){
+        y: (#list){
+          0: (struct){
+          }
+        }
+      }
+    }
+  }
   issue3410: (struct){
     _s: (struct){
       #x: (_){ matchN(1, (#list){
@@ -659,52 +710,149 @@ Result:
         }) }
     }
   }
+  yamlNoCycle: (struct){
+    #c: (#struct){
+      b?: (string){ string }
+      a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
+    }
+    data: (#struct){
+      a: (string){ "{a: \"b: foo\"}" }
+      b?: (string){ string }
+    }
+  }
+  selfCycle: (_|_){
+    // [eval]
+    t1: (_|_){
+      // [eval]
+      c: (_|_){
+        // [eval] selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:15:5
+        // selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:14:20
+        //     ./yamlcycle.cue:15:8
+        // selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:14:20
+        //     ./yamlcycle.cue:15:8
+        // selfCycle.t1.c.d.d.d: structural cycle:
+        //     ./yamlcycle.cue:14:5
+        d: (struct){
+        }
+      }
+    }
+    t2: (struct){
+      c: (struct){
+      }
+    }
+    yamlVal: (_|_){
+      // [eval]
+      t1: (_|_){
+        // [eval]
+        x: (_|_){
+          // [eval]
+          y: (_|_){
+            // [eval] selfCycle.yamlVal.t1.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
+            //     ./yamlcycle.cue:24:8
+            //     ./yamlcycle.cue:25:8
+          }
+        }
+      }
+      t2: (_|_){
+        // [eval]
+        x: (_|_){
+          // [eval]
+          y: (_|_){
+            // [eval] selfCycle.yamlVal.t2.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
+            //     ./yamlcycle.cue:30:8
+            //     ./yamlcycle.cue:31:8
+            //     ./yamlcycle.cue:32:8
+            //     ./yamlcycle.cue:33:8
+          }
+        }
+      }
+    }
+    yamlFun: (_|_){
+      // [eval]
+      t1: (struct){
+        x: (struct){
+          y?: (bool){ true }
+        }
+      }
+      t2: (_|_){
+        // [eval]
+        z: (_|_){
+          // [eval]
+          y: (_|_){
+            // [eval] selfCycle.yamlFun.t2.z.y: error in call to encoding/yaml.Validate: structural cycle:
+            //     ./yamlcycle.cue:41:8
+          }
+        }
+        x: (_|_){
+          // [eval]
+          y: (_|_){
+            // [eval] selfCycle.yamlFun.t2.x.y: error in call to encoding/yaml.Validate: structural cycle:
+            //     ./yamlcycle.cue:41:8
+          }
+        }
+      }
+    }
+    yamlValidatePartial: (_|_){
+      // [structural cycle]
+      x: (_|_){
+        // [structural cycle]
+        y: (_|_){
+          // [structural cycle] selfCycle.yamlValidatePartial.x.y: invalid value "{}" (does not satisfy encoding/yaml.ValidatePartial): error in call to encoding/yaml.ValidatePartial: structural cycle:
+          //     ./yamlcycle.cue:44:8
+          //     ./yamlcycle.cue:45:8
+        }
+      }
+    }
+  }
 }
 -- diff/-out/evalalpha<==>+out/eval --
 diff old new
 --- old
 +++ new
-@@ -3,18 +3,18 @@
-     ./cycle.cue:6:7
-     ./cycle.cue:6:14
-     ./cycle.cue:7:13
+@@ -3,24 +3,39 @@
+     ./cycle.cue:4:7
+     ./cycle.cue:4:14
+     ./cycle.cue:5:13
 -noCycle.t1.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--    ./cycle.cue:6:7
--    ./cycle.cue:6:14
--    ./cycle.cue:7:13
+-    ./cycle.cue:4:7
+-    ./cycle.cue:4:14
+-    ./cycle.cue:5:13
 +noCycle.t1.#x.#x: structural cycle:
-+    ./cycle.cue:6:7
++    ./cycle.cue:4:7
  noCycle.t1._s.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-     ./cycle.cue:6:7
-     ./cycle.cue:6:14
-     ./cycle.cue:7:13
+     ./cycle.cue:4:7
+     ./cycle.cue:4:14
+     ./cycle.cue:5:13
 -noCycle.t1._s.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--    ./cycle.cue:6:7
--    ./cycle.cue:6:14
--    ./cycle.cue:7:13
+-    ./cycle.cue:4:7
+-    ./cycle.cue:4:14
+-    ./cycle.cue:5:13
+-jsonCycle.t1.x.y.y: structural cycle:
+-    ./jsoncycle.cue:4:22
+-listMatchN.structCycle.x.y.y: structural cycle:
+-    ./listmatchncycle.cue:4:23
 +issue3649.cycle.t1.data.a: invalid value {b:"foo"} (does not satisfy matchN): 0 matched, expected 1:
-+    ./cycle.cue:33:6
-+    ./cycle.cue:30:11
-+    ./cycle.cue:33:13
++    ./cycle.cue:31:6
++    ./cycle.cue:28:11
++    ./cycle.cue:31:13
 +issue3649.cycle.t1.data.a.a: structural cycle:
-+    ./cycle.cue:33:6
- selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-     ./cycle.cue:47:5
-     ./cycle.cue:47:12
-@@ -31,18 +31,20 @@
-     ./cycle.cue:48:8
- selfCycle.t1.c.d.d.d: structural cycle:
-     ./cycle.cue:47:5
--selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--    ./cycle.cue:53:5
--    ./cycle.cue:53:12
--    ./cycle.cue:54:5
--selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--    ./cycle.cue:53:5
--    ./cycle.cue:53:12
--    ./cycle.cue:53:20
--selfCycle.t2.c.d.d: structural cycle:
--    ./cycle.cue:53:5
++    ./cycle.cue:31:6
++jsonCycle.t1.x.y: invalid value "{}" (does not satisfy encoding/json.Validate): error in call to encoding/json.Validate: structural cycle:
++    ./jsoncycle.cue:4:8
++    ./jsoncycle.cue:5:8
++listMatchN.structCycle.x.y: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1:
++    ./listmatchncycle.cue:4:8
++    ./listmatchncycle.cue:4:20
++    ./listmatchncycle.cue:5:8
  issue3443.matchIf.#S: cannot call non-function matchIf (type struct):
      ./matchn.cue:16:7
 +issue3443.cycle1.cycle.s: invalid value {n:{n:_}} (does not satisfy matchN): 0 matched, expected 1:
@@ -722,25 +870,67 @@ diff old new
  issue3443.cycle2.fail.#S: invalid value {n:{n:{n:_}}} (does not satisfy matchN): 0 matched, expected 1:
      ./matchn.cue:55:13
      ./matchn.cue:55:20
-@@ -74,10 +76,6 @@
-           //     ./cycle.cue:6:7
-           //     ./cycle.cue:6:14
-           //     ./cycle.cue:7:13
+@@ -53,26 +68,21 @@
+     ./yamlcycle.cue:15:8
+ selfCycle.t1.c.d.d.d: structural cycle:
+     ./yamlcycle.cue:14:5
+-selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+-    ./yamlcycle.cue:20:5
+-    ./yamlcycle.cue:20:12
+-    ./yamlcycle.cue:21:5
+-selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+-    ./yamlcycle.cue:20:5
+-    ./yamlcycle.cue:20:12
+-    ./yamlcycle.cue:20:20
+-selfCycle.t2.c.d.d: structural cycle:
+-    ./yamlcycle.cue:20:5
+-selfCycle.yamlVal.t1.x.y.y: structural cycle:
+-    ./yamlcycle.cue:24:22
+-selfCycle.yamlVal.t2.x.y.y: structural cycle:
+-    ./yamlcycle.cue:32:22
+-selfCycle.yamlFun.t1.x.y.y: structural cycle:
+-    ./yamlcycle.cue:36:29
+-selfCycle.yamlFun.t2.x.y.y: structural cycle:
+-    ./yamlcycle.cue:41:28
+-selfCycle.yamlValidatePartial.x.y.y: structural cycle:
+-    ./yamlcycle.cue:44:29
++selfCycle.yamlVal.t1.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
++    ./yamlcycle.cue:24:8
++    ./yamlcycle.cue:25:8
++selfCycle.yamlVal.t2.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
++    ./yamlcycle.cue:30:8
++    ./yamlcycle.cue:31:8
++    ./yamlcycle.cue:32:8
++    ./yamlcycle.cue:33:8
++selfCycle.yamlFun.t2.x.y: error in call to encoding/yaml.Validate: structural cycle:
++    ./yamlcycle.cue:41:8
++selfCycle.yamlFun.t2.z.y: error in call to encoding/yaml.Validate: structural cycle:
++    ./yamlcycle.cue:41:8
++selfCycle.yamlValidatePartial.x.y: invalid value "{}" (does not satisfy encoding/yaml.ValidatePartial): error in call to encoding/yaml.ValidatePartial: structural cycle:
++    ./yamlcycle.cue:44:8
++    ./yamlcycle.cue:45:8
+ 
+ Result:
+ (_|_){
+@@ -88,10 +98,6 @@
+           //     ./cycle.cue:4:7
+           //     ./cycle.cue:4:14
+           //     ./cycle.cue:5:13
 -          // noCycle.t1._s.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--          //     ./cycle.cue:6:7
--          //     ./cycle.cue:6:14
--          //     ./cycle.cue:7:13
+-          //     ./cycle.cue:4:7
+-          //     ./cycle.cue:4:14
+-          //     ./cycle.cue:5:13
          }
        }
        #x: (_|_){
-@@ -85,26 +83,25 @@
-         //     ./cycle.cue:6:7
-         //     ./cycle.cue:6:14
-         //     ./cycle.cue:7:13
+@@ -99,26 +105,25 @@
+         //     ./cycle.cue:4:7
+         //     ./cycle.cue:4:14
+         //     ./cycle.cue:5:13
 -        // noCycle.t1.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--        //     ./cycle.cue:6:7
--        //     ./cycle.cue:6:14
--        //     ./cycle.cue:7:13
+-        //     ./cycle.cue:4:7
+-        //     ./cycle.cue:4:14
+-        //     ./cycle.cue:5:13
 -      }
 -    }
 -  }
@@ -753,7 +943,7 @@ diff old new
 -            b: (string){ "foo" }
 -          }
 +        // noCycle.t1.#x.#x: structural cycle:
-+        //     ./cycle.cue:6:7
++        //     ./cycle.cue:4:7
 +      }
 +    }
 +  }
@@ -775,7 +965,7 @@ diff old new
                }
              }) }
          }
-@@ -111,7 +108,6 @@
+@@ -125,7 +130,6 @@
        }
        t2: (struct){
          x: (struct){
@@ -783,7 +973,7 @@ diff old new
            y: (struct){
              a: (struct){
                d: (struct){
-@@ -119,14 +115,15 @@
+@@ -133,14 +137,15 @@
                }
              }
            }
@@ -801,7 +991,7 @@ diff old new
                  }
                }) }
            }
-@@ -133,18 +130,27 @@
+@@ -147,18 +152,27 @@
          }
        }
      }
@@ -820,11 +1010,11 @@ diff old new
 +          // [eval]
 +          a: (_|_){
 +            // [eval] issue3649.cycle.t1.data.a: invalid value {b:"foo"} (does not satisfy matchN): 0 matched, expected 1:
-+            //     ./cycle.cue:33:6
-+            //     ./cycle.cue:30:11
-+            //     ./cycle.cue:33:13
++            //     ./cycle.cue:31:6
++            //     ./cycle.cue:28:11
++            //     ./cycle.cue:31:13
 +            // issue3649.cycle.t1.data.a.a: structural cycle:
-+            //     ./cycle.cue:33:6
++            //     ./cycle.cue:31:6
 +            b: (string){ "foo" }
 +          }
 +          b: (string){ string }
@@ -837,39 +1027,40 @@ diff old new
                }
              }) }
          }
-@@ -157,8 +163,8 @@
-       a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
-     }
-     data: (#struct){
--      b?: (string){ string }
-       a: (string){ "{a: \"b: foo\"}" }
-+      b?: (string){ string }
-     }
-   }
-   selfCycle: (_|_){
-@@ -186,19 +192,8 @@
-         }
+@@ -224,8 +238,12 @@
+     t1: (_|_){
+       // [structural cycle]
+       x: (_|_){
+-        // [structural cycle] jsonCycle.t1.x.y.y: structural cycle:
+-        //     ./jsoncycle.cue:4:22
++        // [structural cycle]
++        y: (_|_){
++          // [structural cycle] jsonCycle.t1.x.y: invalid value "{}" (does not satisfy encoding/json.Validate): error in call to encoding/json.Validate: structural cycle:
++          //     ./jsoncycle.cue:4:8
++          //     ./jsoncycle.cue:5:8
++        }
        }
      }
--    t2: (_|_){
--      // [eval]
--      c: (_|_){
--        // [eval] selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--        //     ./cycle.cue:53:5
--        //     ./cycle.cue:53:12
--        //     ./cycle.cue:54:5
--        // selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
--        //     ./cycle.cue:53:5
--        //     ./cycle.cue:53:12
--        //     ./cycle.cue:53:20
--        // selfCycle.t2.c.d.d: structural cycle:
--        //     ./cycle.cue:53:5
-+    t2: (struct){
-+      c: (struct){
+   }
+@@ -234,8 +252,15 @@
+     structCycle: (_|_){
+       // [eval]
+       x: (_|_){
+-        // [eval] listMatchN.structCycle.x.y.y: structural cycle:
+-        //     ./listmatchncycle.cue:4:23
++        // [eval]
++        y: (_|_){
++          // [eval] listMatchN.structCycle.x.y: invalid value [{}] (does not satisfy list.MatchN): number of matched elements is 0: does not satisfy 1:
++          //     ./listmatchncycle.cue:4:8
++          //     ./listmatchncycle.cue:4:20
++          //     ./listmatchncycle.cue:5:8
++          0: (struct){
++          }
++        }
        }
      }
-   }
-@@ -259,20 +254,20 @@
+     ok: (struct){
+@@ -253,20 +278,20 @@
    issue3410: (struct){
      _s: (struct){
        #x: (_){ matchN(1, (#list){
@@ -898,7 +1089,7 @@ diff old new
          }
        }) }
    }
-@@ -279,9 +274,9 @@
+@@ -273,9 +298,9 @@
    issue3420: (struct){
      matches1: (struct){
        #S: (_){ matchN(1, (#list){
@@ -911,7 +1102,7 @@ diff old new
            }
          }) }
        s: (int){ 2 }
-@@ -298,13 +293,13 @@
+@@ -292,13 +317,13 @@
      }
      noCycle: (struct){
        #S: (_){ matchN(1, (#list){
@@ -928,7 +1119,7 @@ diff old new
            n: (struct){
              n: (_){ _ }
            }
-@@ -313,29 +308,43 @@
+@@ -307,29 +332,43 @@
      }
      noCycle2: (struct){
        #S: (_){ matchN(1, (#list){
@@ -985,7 +1176,7 @@ diff old new
            n: (struct){
              n: (_){ _ }
            }
-@@ -388,11 +397,11 @@
+@@ -382,11 +421,11 @@
          //     ./matchn.cue:63:24
        }
        #s: (_){ matchN(1, (#list){
@@ -999,52 +1190,149 @@ diff old new
            }
          }) }
      }
+@@ -397,8 +436,8 @@
+       a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
+     }
+     data: (#struct){
+-      b?: (string){ string }
+       a: (string){ "{a: \"b: foo\"}" }
++      b?: (string){ string }
+     }
+   }
+   selfCycle: (_|_){
+@@ -426,19 +465,8 @@
+         }
+       }
+     }
+-    t2: (_|_){
+-      // [eval]
+-      c: (_|_){
+-        // [eval] selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+-        //     ./yamlcycle.cue:20:5
+-        //     ./yamlcycle.cue:20:12
+-        //     ./yamlcycle.cue:21:5
+-        // selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+-        //     ./yamlcycle.cue:20:5
+-        //     ./yamlcycle.cue:20:12
+-        //     ./yamlcycle.cue:20:20
+-        // selfCycle.t2.c.d.d: structural cycle:
+-        //     ./yamlcycle.cue:20:5
++    t2: (struct){
++      c: (struct){
+       }
+     }
+     yamlVal: (_|_){
+@@ -446,25 +474,33 @@
+       t1: (_|_){
+         // [eval]
+         x: (_|_){
+-          // [eval] selfCycle.yamlVal.t1.x.y.y: structural cycle:
+-          //     ./yamlcycle.cue:24:22
+-        }
+-      }
+-      t2: (_|_){
+-        // [eval]
+-        x: (_|_){
+-          // [eval] selfCycle.yamlVal.t2.x.y.y: structural cycle:
+-          //     ./yamlcycle.cue:32:22
++          // [eval]
++          y: (_|_){
++            // [eval] selfCycle.yamlVal.t1.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
++            //     ./yamlcycle.cue:24:8
++            //     ./yamlcycle.cue:25:8
++          }
++        }
++      }
++      t2: (_|_){
++        // [eval]
++        x: (_|_){
++          // [eval]
++          y: (_|_){
++            // [eval] selfCycle.yamlVal.t2.x.y: invalid value "{}" (does not satisfy encoding/yaml.Validate): error in call to encoding/yaml.Validate: structural cycle:
++            //     ./yamlcycle.cue:30:8
++            //     ./yamlcycle.cue:31:8
++            //     ./yamlcycle.cue:32:8
++            //     ./yamlcycle.cue:33:8
++          }
+         }
+       }
+     }
+     yamlFun: (_|_){
+       // [eval]
+-      t1: (_|_){
+-        // [structural cycle]
+-        x: (_|_){
+-          // [structural cycle] selfCycle.yamlFun.t1.x.y.y: structural cycle:
+-          //     ./yamlcycle.cue:36:29
++      t1: (struct){
++        x: (struct){
++          y?: (bool){ true }
+         }
+       }
+       t2: (_|_){
+@@ -472,13 +508,16 @@
+         z: (_|_){
+           // [eval]
+           y: (_|_){
+-            // [eval] selfCycle.yamlFun.t2.x.y.y: structural cycle:
+-            //     ./yamlcycle.cue:41:28
+-          }
+-        }
+-        x: (_|_){
+-          // [eval] selfCycle.yamlFun.t2.x.y.y: structural cycle:
+-          //     ./yamlcycle.cue:41:28
++            // [eval] selfCycle.yamlFun.t2.z.y: error in call to encoding/yaml.Validate: structural cycle:
++            //     ./yamlcycle.cue:41:8
++          }
++        }
++        x: (_|_){
++          // [eval]
++          y: (_|_){
++            // [eval] selfCycle.yamlFun.t2.x.y: error in call to encoding/yaml.Validate: structural cycle:
++            //     ./yamlcycle.cue:41:8
++          }
+         }
+       }
+     }
+@@ -485,8 +524,12 @@
+     yamlValidatePartial: (_|_){
+       // [structural cycle]
+       x: (_|_){
+-        // [structural cycle] selfCycle.yamlValidatePartial.x.y.y: structural cycle:
+-        //     ./yamlcycle.cue:44:29
++        // [structural cycle]
++        y: (_|_){
++          // [structural cycle] selfCycle.yamlValidatePartial.x.y: invalid value "{}" (does not satisfy encoding/yaml.ValidatePartial): error in call to encoding/yaml.ValidatePartial: structural cycle:
++          //     ./yamlcycle.cue:44:8
++          //     ./yamlcycle.cue:45:8
++        }
+       }
+     }
+   }
 -- diff/todo/p2 --
 issue3443: Sort out differences in reporting of cycles.
 -- out/eval --
 Errors:
 noCycle.t1.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
 noCycle.t1.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
 noCycle.t1._s.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
 noCycle.t1._s.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:6:7
-    ./cycle.cue:6:14
-    ./cycle.cue:7:13
-selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:48:5
-selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:47:20
-    ./cycle.cue:48:8
-selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:47:5
-    ./cycle.cue:47:12
-    ./cycle.cue:47:20
-    ./cycle.cue:48:8
-selfCycle.t1.c.d.d.d: structural cycle:
-    ./cycle.cue:47:5
-selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:53:5
-    ./cycle.cue:53:12
-    ./cycle.cue:54:5
-selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-    ./cycle.cue:53:5
-    ./cycle.cue:53:12
-    ./cycle.cue:53:20
-selfCycle.t2.c.d.d: structural cycle:
-    ./cycle.cue:53:5
+    ./cycle.cue:4:7
+    ./cycle.cue:4:14
+    ./cycle.cue:5:13
+jsonCycle.t1.x.y.y: structural cycle:
+    ./jsoncycle.cue:4:22
+listMatchN.structCycle.x.y.y: structural cycle:
+    ./listmatchncycle.cue:4:23
 issue3443.matchIf.#S: cannot call non-function matchIf (type struct):
     ./matchn.cue:16:7
 issue3443.cycle2.fail.#S: invalid value {n:{n:{n:_}}} (does not satisfy matchN): 0 matched, expected 1:
@@ -1063,6 +1351,42 @@ issue3443.cycle2.fail.#S.n.n: invalid value {n:{n:{n:_}}} (does not satisfy matc
     ./matchn.cue:55:43
 issue3443.cycle2.fail.#S.n.n.n: structural cycle:
     ./matchn.cue:55:13
+selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:15:5
+selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:14:20
+    ./yamlcycle.cue:15:8
+selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:14:5
+    ./yamlcycle.cue:14:12
+    ./yamlcycle.cue:14:20
+    ./yamlcycle.cue:15:8
+selfCycle.t1.c.d.d.d: structural cycle:
+    ./yamlcycle.cue:14:5
+selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:20:5
+    ./yamlcycle.cue:20:12
+    ./yamlcycle.cue:21:5
+selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+    ./yamlcycle.cue:20:5
+    ./yamlcycle.cue:20:12
+    ./yamlcycle.cue:20:20
+selfCycle.t2.c.d.d: structural cycle:
+    ./yamlcycle.cue:20:5
+selfCycle.yamlVal.t1.x.y.y: structural cycle:
+    ./yamlcycle.cue:24:22
+selfCycle.yamlVal.t2.x.y.y: structural cycle:
+    ./yamlcycle.cue:32:22
+selfCycle.yamlFun.t1.x.y.y: structural cycle:
+    ./yamlcycle.cue:36:29
+selfCycle.yamlFun.t2.x.y.y: structural cycle:
+    ./yamlcycle.cue:41:28
+selfCycle.yamlValidatePartial.x.y.y: structural cycle:
+    ./yamlcycle.cue:44:29
 
 Result:
 (_|_){
@@ -1075,24 +1399,24 @@ Result:
         // [eval]
         #x: (_|_){
           // [eval] noCycle.t1._s.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-          //     ./cycle.cue:6:7
-          //     ./cycle.cue:6:14
-          //     ./cycle.cue:7:13
+          //     ./cycle.cue:4:7
+          //     ./cycle.cue:4:14
+          //     ./cycle.cue:5:13
           // noCycle.t1._s.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-          //     ./cycle.cue:6:7
-          //     ./cycle.cue:6:14
-          //     ./cycle.cue:7:13
+          //     ./cycle.cue:4:7
+          //     ./cycle.cue:4:14
+          //     ./cycle.cue:5:13
         }
       }
       #x: (_|_){
         // [eval] noCycle.t1.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:6:7
-        //     ./cycle.cue:6:14
-        //     ./cycle.cue:7:13
+        //     ./cycle.cue:4:7
+        //     ./cycle.cue:4:14
+        //     ./cycle.cue:5:13
         // noCycle.t1.#x.#x: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:6:7
-        //     ./cycle.cue:6:14
-        //     ./cycle.cue:7:13
+        //     ./cycle.cue:4:7
+        //     ./cycle.cue:4:14
+        //     ./cycle.cue:5:13
       }
     }
   }
@@ -1155,57 +1479,6 @@ Result:
       }
     }
   }
-  yamlNoCycle: (struct){
-    #c: (#struct){
-      b?: (string){ string }
-      a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
-    }
-    data: (#struct){
-      b?: (string){ string }
-      a: (string){ "{a: \"b: foo\"}" }
-    }
-  }
-  selfCycle: (_|_){
-    // [eval]
-    t1: (_|_){
-      // [eval]
-      c: (_|_){
-        // [eval] selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:48:5
-        // selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:47:20
-        //     ./cycle.cue:48:8
-        // selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:47:5
-        //     ./cycle.cue:47:12
-        //     ./cycle.cue:47:20
-        //     ./cycle.cue:48:8
-        // selfCycle.t1.c.d.d.d: structural cycle:
-        //     ./cycle.cue:47:5
-        d: (struct){
-        }
-      }
-    }
-    t2: (_|_){
-      // [eval]
-      c: (_|_){
-        // [eval] selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:53:5
-        //     ./cycle.cue:53:12
-        //     ./cycle.cue:54:5
-        // selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
-        //     ./cycle.cue:53:5
-        //     ./cycle.cue:53:12
-        //     ./cycle.cue:53:20
-        // selfCycle.t2.c.d.d: structural cycle:
-        //     ./cycle.cue:53:5
-      }
-    }
-  }
   builtinCyclePerm0: (struct){
     X: (string){ "mod.test" }
     Y: (struct){
@@ -1260,6 +1533,37 @@ Result:
       host: (string){ "mod.test" }
     }
   }
+  jsonCycle: (_|_){
+    // [structural cycle]
+    t1: (_|_){
+      // [structural cycle]
+      x: (_|_){
+        // [structural cycle] jsonCycle.t1.x.y.y: structural cycle:
+        //     ./jsoncycle.cue:4:22
+      }
+    }
+  }
+  listMatchN: (_|_){
+    // [eval]
+    structCycle: (_|_){
+      // [eval]
+      x: (_|_){
+        // [eval] listMatchN.structCycle.x.y.y: structural cycle:
+        //     ./listmatchncycle.cue:4:23
+      }
+    }
+    ok: (struct){
+      x: (struct){
+        y?: (list){ list.MatchN(1, listMatchN.ok.x) }
+      }
+      z: (struct){
+        y: (#list){
+          0: (struct){
+          }
+        }
+      }
+    }
+  }
   issue3410: (struct){
     _s: (struct){
       #x: (_){ matchN(1, (#list){
@@ -1401,6 +1705,105 @@ Result:
         }) }
     }
   }
+  yamlNoCycle: (struct){
+    #c: (#struct){
+      b?: (string){ string }
+      a?: ((string|bytes)){ "encoding/yaml".Validate(yamlNoCycle.#c) }
+    }
+    data: (#struct){
+      b?: (string){ string }
+      a: (string){ "{a: \"b: foo\"}" }
+    }
+  }
+  selfCycle: (_|_){
+    // [eval]
+    t1: (_|_){
+      // [eval]
+      c: (_|_){
+        // [eval] selfCycle.t1.c: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:15:5
+        // selfCycle.t1.c.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:14:20
+        //     ./yamlcycle.cue:15:8
+        // selfCycle.t1.c.d.d: invalid value {d:{}} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:14:5
+        //     ./yamlcycle.cue:14:12
+        //     ./yamlcycle.cue:14:20
+        //     ./yamlcycle.cue:15:8
+        // selfCycle.t1.c.d.d.d: structural cycle:
+        //     ./yamlcycle.cue:14:5
+        d: (struct){
+        }
+      }
+    }
+    t2: (_|_){
+      // [eval]
+      c: (_|_){
+        // [eval] selfCycle.t2.c: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:20:5
+        //     ./yamlcycle.cue:20:12
+        //     ./yamlcycle.cue:21:5
+        // selfCycle.t2.c.d: invalid value {} (does not satisfy matchN): 0 matched, expected 1:
+        //     ./yamlcycle.cue:20:5
+        //     ./yamlcycle.cue:20:12
+        //     ./yamlcycle.cue:20:20
+        // selfCycle.t2.c.d.d: structural cycle:
+        //     ./yamlcycle.cue:20:5
+      }
+    }
+    yamlVal: (_|_){
+      // [eval]
+      t1: (_|_){
+        // [eval]
+        x: (_|_){
+          // [eval] selfCycle.yamlVal.t1.x.y.y: structural cycle:
+          //     ./yamlcycle.cue:24:22
+        }
+      }
+      t2: (_|_){
+        // [eval]
+        x: (_|_){
+          // [eval] selfCycle.yamlVal.t2.x.y.y: structural cycle:
+          //     ./yamlcycle.cue:32:22
+        }
+      }
+    }
+    yamlFun: (_|_){
+      // [eval]
+      t1: (_|_){
+        // [structural cycle]
+        x: (_|_){
+          // [structural cycle] selfCycle.yamlFun.t1.x.y.y: structural cycle:
+          //     ./yamlcycle.cue:36:29
+        }
+      }
+      t2: (_|_){
+        // [eval]
+        z: (_|_){
+          // [eval]
+          y: (_|_){
+            // [eval] selfCycle.yamlFun.t2.x.y.y: structural cycle:
+            //     ./yamlcycle.cue:41:28
+          }
+        }
+        x: (_|_){
+          // [eval] selfCycle.yamlFun.t2.x.y.y: structural cycle:
+          //     ./yamlcycle.cue:41:28
+        }
+      }
+    }
+    yamlValidatePartial: (_|_){
+      // [structural cycle]
+      x: (_|_){
+        // [structural cycle] selfCycle.yamlValidatePartial.x.y.y: structural cycle:
+        //     ./yamlcycle.cue:44:29
+      }
+    }
+  }
 }
 -- out/compile --
 --- cycle.cue
@@ -1478,38 +1881,6 @@ Result:
       }
     }
   }
-  yamlNoCycle: {
-    #c: {
-      b?: string
-      a?: 〈import;"encoding/yaml"〉.Validate(〈1;#c〉)
-    }
-    data: 〈0;#c〉
-    data: {
-      a: "{a: \"b: foo\"}"
-    }
-  }
-  selfCycle: {
-    t1: {
-      c: matchN(1, [
-        {
-          d: 〈2;c〉
-        },
-      ])
-      c: {
-        d: {}
-      }
-    }
-  }
-  selfCycle: {
-    t2: {
-      c: matchN(1, [
-        {
-          d: 〈2;c〉
-        },
-      ])
-      c: {}
-    }
-  }
 }
 --- in.cue
 {
@@ -1562,6 +1933,47 @@ Result:
     }
   }
 }
+--- jsoncycle.cue
+{
+  jsonCycle: {
+    t1: {
+      x: {
+        y: 〈import;"encoding/json"〉.Validate(〈1;x〉)
+      }
+      x: {
+        y: "{}"
+      }
+    }
+  }
+}
+--- listmatchncycle.cue
+{
+  listMatchN: {
+    structCycle: {
+      x: {
+        y: 〈import;list〉.MatchN(1, 〈1;x〉)
+      }
+      x: {
+        y: [
+          {},
+        ]
+      }
+    }
+  }
+  listMatchN: {
+    ok: {
+      x: {
+        y?: 〈import;list〉.MatchN(1, 〈1;x〉)
+      }
+      z: 〈0;x〉
+      z: {
+        y: [
+          {},
+        ]
+      }
+    }
+  }
+}
 --- matchn.cue
 {
   issue3410: {
@@ -1662,3 +2074,100 @@ Result:
     }
   }
 }
+--- yamlcycle.cue
+{
+  yamlNoCycle: {
+    #c: {
+      b?: string
+      a?: 〈import;"encoding/yaml"〉.Validate(〈1;#c〉)
+    }
+    data: 〈0;#c〉
+    data: {
+      a: "{a: \"b: foo\"}"
+    }
+  }
+  selfCycle: {
+    t1: {
+      c: matchN(1, [
+        {
+          d: 〈2;c〉
+        },
+      ])
+      c: {
+        d: {}
+      }
+    }
+  }
+  selfCycle: {
+    t2: {
+      c: matchN(1, [
+        {
+          d: 〈2;c〉
+        },
+      ])
+      c: {}
+    }
+  }
+  selfCycle: {
+    yamlVal: {
+      t1: {
+        x: {
+          y: 〈import;"encoding/yaml"〉.Validate(〈1;x〉)
+        }
+        x: {
+          y: "{}"
+        }
+      }
+    }
+  }
+  selfCycle: {
+    yamlVal: {
+      t2: {
+        x: {
+          y: 〈import;"encoding/yaml"〉.Validate(〈1;x〉)
+        }
+        x: {
+          y: "{}"
+        }
+        x: {
+          y: 〈import;"encoding/yaml"〉.Validate(〈1;x〉)
+        }
+        x: {
+          y: "{}"
+        }
+      }
+    }
+  }
+  selfCycle: {
+    yamlFun: {
+      t1: {
+        x: {
+          y?: 〈import;"encoding/yaml"〉.Validate("{}", 〈1;x〉)
+        }
+      }
+    }
+  }
+  selfCycle: {
+    yamlFun: {
+      t2: {
+        z: (〈0;x〉 & _|_(no sharing))
+        z: {
+          y: "{}"
+        }
+        x: {
+          y: 〈import;"encoding/yaml"〉.Validate("{}", 〈1;x〉)
+        }
+      }
+    }
+  }
+  selfCycle: {
+    yamlValidatePartial: {
+      x: {
+        y: 〈import;"encoding/yaml"〉.ValidatePartial(〈1;x〉)
+      }
+      x: {
+        y: "{}"
+      }
+    }
+  }
+}
diff --git a/internal/core/adt/eval_test.go b/internal/core/adt/eval_test.go
index 159a4009a..1bf1b6234 100644
--- a/internal/core/adt/eval_test.go
+++ b/internal/core/adt/eval_test.go
@@ -76,6 +76,7 @@ var needFix = map[string]string{
 // counter errors.
 // TODO: These counters should all go to zero.
 var skipDebugDepErrors = map[string]int{
+	"cycle/builtins":           3,
 	"disjunctions/elimination": 4,
 	"eval/notify":              3,
 }
diff --git a/internal/pkg/context.go b/internal/pkg/context.go
index 374903843..ff0315a92 100644
--- a/internal/pkg/context.go
+++ b/internal/pkg/context.go
@@ -51,8 +51,13 @@ func (c *CallCtxt) Do() bool {
 }
 
 // Schema returns the ith argument as is, without converting it to a cue.Value.
+//
+// TODO: Schema should use CallContext.Expr to capture cycle information.
+// However, this only makes sense if functions also use the same OpContext for
+// further evaluation. We should enforce as we port the old calls.
 func (c *CallCtxt) Schema(i int) Schema {
-	return value.Make(c.ctx, c.args[i])
+	v := c.Expr(i)
+	return value.Make(c.ctx, v)
 }
 
 // Value returns a finalized cue.Value for the ith argument.
diff --git a/pkg/encoding/json/manual.go b/pkg/encoding/json/manual.go
index c33d4f0bc..54368c1f5 100644
--- a/pkg/encoding/json/manual.go
+++ b/pkg/encoding/json/manual.go
@@ -134,6 +134,11 @@ func Unmarshal(b []byte) (ast.Expr, error) {
 // specified by v.
 func Validate(b []byte, v pkg.Schema) (bool, error) {
 	c := value.OpContext(v)
+	return validate(c, b, v)
+}
+
+// validate is the actual implementation of Validate.
+func validate(c *adt.OpContext, b []byte, v pkg.Schema) (bool, error) {
 	if !json.Valid(b) {
 		return false, fmt.Errorf("json: invalid JSON")
 	}
diff --git a/pkg/encoding/json/pkg.go b/pkg/encoding/json/pkg.go
index 189709db1..a8e6d1d3b 100644
--- a/pkg/encoding/json/pkg.go
+++ b/pkg/encoding/json/pkg.go
@@ -123,7 +123,7 @@ var p = &pkg.Package{
 		Func: func(c *pkg.CallCtxt) {
 			b, v := c.Bytes(0), c.Schema(1)
 			if c.Do() {
-				c.Ret, c.Err = Validate(b, v)
+				c.Ret, c.Err = validate(c.OpContext(), b, v)
 			}
 		},
 	}},
diff --git a/pkg/encoding/json/testdata/gen.txtar b/pkg/encoding/json/testdata/gen.txtar
index fac2d77b0..aeba97a14 100644
--- a/pkg/encoding/json/testdata/gen.txtar
+++ b/pkg/encoding/json/testdata/gen.txtar
@@ -116,7 +116,7 @@ validate: {
 		schema: {
 			a: <3
 		}
-		result: _|_ // validate.t2.result: error in call to encoding/json.Validate: validate.t2.schema.a: invalid value 10 (out of bound <3)
+		result: _|_ // validate.t2.result: error in call to encoding/json.Validate: validate.t2.result.a: invalid value 10 (out of bound <3)
 	}
 	disjunctionRequired: {
 		str: *"{\"a\":10}" | string
diff --git a/pkg/encoding/yaml/manual.go b/pkg/encoding/yaml/manual.go
index 71d0bd3ae..5bf3db396 100644
--- a/pkg/encoding/yaml/manual.go
+++ b/pkg/encoding/yaml/manual.go
@@ -20,6 +20,7 @@ import (
 
 	"cuelang.org/go/cue"
 	"cuelang.org/go/cue/ast"
+	"cuelang.org/go/internal/core/adt"
 	cueyaml "cuelang.org/go/internal/encoding/yaml"
 	"cuelang.org/go/internal/pkg"
 	"cuelang.org/go/internal/value"
@@ -87,15 +88,31 @@ func UnmarshalStream(data []byte) (ast.Expr, error) {
 // Validate validates YAML and confirms it is an instance of schema.
 // If the YAML source is a stream, every object must match v.
 func Validate(b []byte, v pkg.Schema) (bool, error) {
+	// This function is left for Go documentation. The package entry calls
+	// cueyaml.Validate directly, passing it the call context.
+
 	ctx := value.OpContext(v)
 	return cueyaml.Validate(ctx, b, v)
 }
 
+// validate is the actual implementation of Validate.
+func validate(c *adt.OpContext, b []byte, v pkg.Schema) (bool, error) {
+	return cueyaml.Validate(c, b, v)
+}
+
 // ValidatePartial validates YAML and confirms it matches the constraints
 // specified by v using unification. This means that b must be consistent with,
 // but does not have to be an instance of v. If the YAML source is a stream,
 // every object must match v.
 func ValidatePartial(b []byte, v pkg.Schema) (bool, error) {
+	// This function is left for Go documentation. The package entry calls
+	// cueyaml.ValidatePartial directly, passing it the call context.
+
 	ctx := value.OpContext(v)
 	return cueyaml.ValidatePartial(ctx, b, v)
 }
+
+// validatePartial is the actual implementation of ValidatePartial.
+func validatePartial(c *adt.OpContext, b []byte, v pkg.Schema) (bool, error) {
+	return cueyaml.ValidatePartial(c, b, v)
+}
diff --git a/pkg/encoding/yaml/pkg.go b/pkg/encoding/yaml/pkg.go
index d1a31f150..4c117d447 100644
--- a/pkg/encoding/yaml/pkg.go
+++ b/pkg/encoding/yaml/pkg.go
@@ -73,7 +73,7 @@ var p = &pkg.Package{
 		Func: func(c *pkg.CallCtxt) {
 			b, v := c.Bytes(0), c.Schema(1)
 			if c.Do() {
-				c.Ret, c.Err = Validate(b, v)
+				c.Ret, c.Err = validate(c.OpContext(), b, v)
 			}
 		},
 	}, {
@@ -87,7 +87,7 @@ var p = &pkg.Package{
 		Func: func(c *pkg.CallCtxt) {
 			b, v := c.Bytes(0), c.Schema(1)
 			if c.Do() {
-				c.Ret, c.Err = ValidatePartial(b, v)
+				c.Ret, c.Err = validatePartial(c.OpContext(), b, v)
 			}
 		},
 	}},
diff --git a/pkg/encoding/yaml/testdata/gen.txtar b/pkg/encoding/yaml/testdata/gen.txtar
index 1843ced0b..f5b1a551c 100644
--- a/pkg/encoding/yaml/testdata/gen.txtar
+++ b/pkg/encoding/yaml/testdata/gen.txtar
@@ -51,10 +51,10 @@ unmarshalTrailingInput.invalid: error in call to encoding/yaml.Unmarshal: expect
     ./in.cue:28:11
 
 Result:
-t1: _|_ // t1: error in call to encoding/yaml.Validate: a: invalid value 4 (out of bound <3)
+t1: _|_ // t1: error in call to encoding/yaml.Validate: t1.a: invalid value 4 (out of bound <3)
 t2: true
-t3: _|_ // t3: error in call to encoding/yaml.Validate: b: incomplete value int
-t4: _|_ // t4: error in call to encoding/yaml.ValidatePartial: a: invalid value 4 (out of bound <3)
+t3: _|_ // t3: error in call to encoding/yaml.Validate: t3.b: incomplete value int
+t4: _|_ // t4: error in call to encoding/yaml.ValidatePartial: t4.a: invalid value 4 (out of bound <3)
 t5: true
 t6: true
 t7: """
diff --git a/pkg/encoding/yaml/testdata/validate.txtar b/pkg/encoding/yaml/testdata/validate.txtar
index 918f42827..f21abd615 100644
--- a/pkg/encoding/yaml/testdata/validate.txtar
+++ b/pkg/encoding/yaml/testdata/validate.txtar
@@ -79,7 +79,7 @@ validate: {
 	// TODO: fix this test: the second disjunct should be eliminated, so there
 	// should not be a concreteness error.
 	t1: {
-		ok1: _|_ // validate.t1.ok1: invalid value "a: 2" (does not satisfy encoding/yaml.Validate): validate.t1.ok1: error in call to encoding/yaml.Validate: incomplete value {a:2} | {a:2,b!:int}
+		ok1: _|_ // validate.t1.ok1: invalid value "a: 2" (does not satisfy encoding/yaml.Validate): validate.t1.ok1: error in call to encoding/yaml.Validate: validate.t1.ok1: incomplete value {a:2} | {a:2,b!:int}
 		ok2: "a: 2"
 		ok3: "a: 2"
 	}
diff --git a/pkg/gen.go b/pkg/gen.go
index ff39d1fd3..d96acab98 100644
--- a/pkg/gen.go
+++ b/pkg/gen.go
@@ -338,12 +338,17 @@ func (g *generator) genFunc(fn *types.Func) {
 
 	fmt.Fprintf(g.w, "Name: %q,\n", fn.Name())
 
+	needCallContext := false
 	args := []string{}
 	vals := []string{}
 	kind := []string{}
 	for i := 0; i < params.Len(); i++ {
 		param := params.At(i)
-		methodName := g.callCtxtGetter(param.Type())
+		typ := param.Type()
+		if typ.String() == "cuelang.org/go/internal/pkg.Schema" {
+			needCallContext = true
+		}
+		methodName := g.callCtxtGetter(typ)
 		argKind := g.adtKind(param.Type())
 		vals = append(vals, fmt.Sprintf("c.%s(%d)", methodName, len(args)))
 		args = append(args, param.Name())
@@ -368,6 +373,17 @@ func (g *generator) genFunc(fn *types.Func) {
 		init = fmt.Sprintf("%s := %s", argList, valList)
 	}
 
+	name := fn.Name()
+	if needCallContext {
+		argList = "c.OpContext(), " + argList
+
+		// Main function is used for Godoc documentation. Once we have proper
+		// CUE function signatures, we can remove these stubs.
+		// NOTE: this will not work for scripts that are not cased. But this
+		// is intended to be a temporary situation anyway.
+		name = strings.ToLower(name[:1]) + name[1:]
+	}
+
 	fmt.Fprintf(g.w, "Func: func(c *pkg.CallCtxt) {")
 	defer fmt.Fprintln(g.w, "},")
 	fmt.Fprintln(g.w)
@@ -377,9 +393,9 @@ func (g *generator) genFunc(fn *types.Func) {
 	fmt.Fprintln(g.w, "if c.Do() {")
 	defer fmt.Fprintln(g.w, "}")
 	if results.Len() == 1 {
-		fmt.Fprintf(g.w, "c.Ret = %s(%s)", fn.Name(), argList)
+		fmt.Fprintf(g.w, "c.Ret = %s(%s)", name, argList)
 	} else {
-		fmt.Fprintf(g.w, "c.Ret, c.Err = %s(%s)", fn.Name(), argList)
+		fmt.Fprintf(g.w, "c.Ret, c.Err = %s(%s)", name, argList)
 	}
 }
 
diff --git a/pkg/list/list.go b/pkg/list/list.go
index 8e7ee79d7..e42162feb 100644
--- a/pkg/list/list.go
+++ b/pkg/list/list.go
@@ -333,6 +333,11 @@ func Contains(a []cue.Value, v cue.Value) bool {
 // Likewise, "matchValue" will usually be a non-concrete value.
 func MatchN(list []cue.Value, n pkg.Schema, matchValue pkg.Schema) (bool, error) {
 	c := value.OpContext(n)
+	return matchN(c, list, n, matchValue)
+}
+
+// matchN is the actual implementation of MatchN.
+func matchN(c *adt.OpContext, list []cue.Value, n pkg.Schema, matchValue pkg.Schema) (bool, error) {
 	var nmatch int64
 	for _, w := range list {
 		vx := adt.Unify(c, value.Vertex(matchValue), value.Vertex(w))
@@ -342,7 +347,7 @@ func MatchN(list []cue.Value, n pkg.Schema, matchValue pkg.Schema) (bool, error)
 		}
 	}
 
-	ctx := value.Context(n)
+	ctx := value.Context(c)
 
 	if err := n.Unify(ctx.Encode(nmatch)).Err(); err != nil {
 		return false, pkg.ValidationError{B: &adt.Bottom{
diff --git a/pkg/list/pkg.go b/pkg/list/pkg.go
index b58dc3a48..0cc45bf8d 100644
--- a/pkg/list/pkg.go
+++ b/pkg/list/pkg.go
@@ -167,7 +167,7 @@ var p = &pkg.Package{
 		Func: func(c *pkg.CallCtxt) {
 			list, n, matchValue := c.List(0), c.Schema(1), c.Schema(2)
 			if c.Do() {
-				c.Ret, c.Err = MatchN(list, n, matchValue)
+				c.Ret, c.Err = matchN(c.OpContext(), list, n, matchValue)
 			}
 		},
 	}, {