internal/core/adt: fix panic due to envDisjunct corruption

We need to further investigate this, but this
fix effectively makes envDisjunct data
immutable once processing started, ensuring
the integrity of the processing.

Leaving open until we remove the TODO

Issue #3857

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I995294e280afee2302199e8599f97d17d9e80798
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1212383
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: mpvl

cue/testdata/disjunctions/issue3857.txtar

@@ -0,0 +1,381 @@
+-- in.cue --
+reduced: t1: {
+	S: { if true { a: U } }
+	x: S
+	x: {
+	["a"]: b: 1 | T
+	d: b: x.a
+	}
+	T: 1
+	U: b: 1 | 1
+}
+issue3851: t1: {
+	#Top: _
+	#Config: {
+	disj: _ | *"default"
+	shared: _
+	}
+
+	#Schema: {
+	[string]: #Config
+	if true {
+		one: shared: "foo"
+	}
+	}
+
+	out: #Schema
+	out: {
+	["one"]: disj: _ | #Top
+	two: shared: out.one.shared
+	}
+}
+issue3851: t2: {
+	#Top: _
+	#Config: {
+	disj: _ | *{}
+	shared: _
+	}
+
+	#Env: {
+	conf: [string]: #Config
+	if true {
+		conf: one: shared: "foo"
+	}
+	}
+
+	env1: #Env
+
+	[string]: {
+	conf: ["one"]: disj: {} | #Top
+	conf: two: shared: conf.one.shared
+	}
+}
+-- out/eval/stats --
+Leaks:  6
+Freed:  90
+Reused: 79
+Allocs: 17
+Retain: 2
+
+Unifications: 60
+Conjuncts:    151
+Disjuncts:    98
+-- out/evalalpha --
+(struct){
+  reduced: (struct){
+    t1: (struct){
+      S: (struct){
+        a: ~(reduced.t1.U)
+      }
+      x: (struct){
+        d: (struct){
+          b: ~(reduced.t1.x.a)
+        }
+        a: (struct){
+          b: (int){ 1 }
+        }
+      }
+      T: (int){ 1 }
+      U: (struct){
+        b: (int){ 1 }
+      }
+    }
+  }
+  issue3851: (struct){
+    t1: (struct){
+      #Top: (_){ _ }
+      #Config: (#struct){
+        disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        shared: (_){ _ }
+      }
+      #Schema: (#struct){
+        one: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        }
+      }
+      out: (#struct){
+        two: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        }
+        one: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ _ }
+        }
+      }
+    }
+    t2: (struct){
+      #Top: (_){ _ }
+      #Config: (#struct){
+        disj: (_){ |(*(#struct){
+          }, (_){ _ }) }
+        shared: (_){ _ }
+      }
+      #Env: (#struct){
+        conf: (#struct){
+          one: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }) }
+          }
+        }
+      }
+      env1: (#struct){
+        conf: (#struct){
+          two: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }) }
+          }
+          one: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }, (#struct){
+              }, (_){ _ }) }
+          }
+        }
+      }
+    }
+  }
+}
+-- diff/-out/evalalpha<==>+out/eval --
+diff old new
+--- old
++++ new
+@@ -2,18 +2,14 @@
+   reduced: (struct){
+     t1: (struct){
+       S: (struct){
+-        a: (struct){
+-          b: (int){ 1 }
+-        }
++        a: ~(reduced.t1.U)
+       }
+       x: (struct){
+-        a: (struct){
+-          b: (int){ 1 }
+-        }
+         d: (struct){
+-          b: (struct){
+-            b: (int){ 1 }
+-          }
++          b: ~(reduced.t1.x.a)
++        }
++        a: (struct){
++          b: (int){ 1 }
+         }
+       }
+       T: (int){ 1 }
+@@ -36,14 +32,14 @@
+         }
+       }
+       out: (#struct){
+-        one: (#struct){
+-          shared: (string){ "foo" }
+-          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+-        }
+         two: (#struct){
+           shared: (string){ "foo" }
+           disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+         }
++        one: (#struct){
++          shared: (string){ "foo" }
++          disj: (_){ _ }
++        }
+       }
+     }
+     t2: (struct){
+@@ -64,17 +60,17 @@
+       }
+       env1: (#struct){
+         conf: (#struct){
+-          one: (#struct){
+-            shared: (string){ "foo" }
+-            disj: (_){ |(*(#struct){
+-              }, (_){ _ }, (struct){
+-              }) }
+-          }
+           two: (#struct){
+             shared: (string){ "foo" }
+             disj: (_){ |(*(#struct){
+               }, (_){ _ }) }
+           }
++          one: (#struct){
++            shared: (string){ "foo" }
++            disj: (_){ |(*(#struct){
++              }, (_){ _ }, (#struct){
++              }, (_){ _ }) }
++          }
+         }
+       }
+     }
+-- out/eval --
+(struct){
+  reduced: (struct){
+    t1: (struct){
+      S: (struct){
+        a: (struct){
+          b: (int){ 1 }
+        }
+      }
+      x: (struct){
+        a: (struct){
+          b: (int){ 1 }
+        }
+        d: (struct){
+          b: (struct){
+            b: (int){ 1 }
+          }
+        }
+      }
+      T: (int){ 1 }
+      U: (struct){
+        b: (int){ 1 }
+      }
+    }
+  }
+  issue3851: (struct){
+    t1: (struct){
+      #Top: (_){ _ }
+      #Config: (#struct){
+        disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        shared: (_){ _ }
+      }
+      #Schema: (#struct){
+        one: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        }
+      }
+      out: (#struct){
+        one: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        }
+        two: (#struct){
+          shared: (string){ "foo" }
+          disj: (_){ |(*(string){ "default" }, (_){ _ }) }
+        }
+      }
+    }
+    t2: (struct){
+      #Top: (_){ _ }
+      #Config: (#struct){
+        disj: (_){ |(*(#struct){
+          }, (_){ _ }) }
+        shared: (_){ _ }
+      }
+      #Env: (#struct){
+        conf: (#struct){
+          one: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }) }
+          }
+        }
+      }
+      env1: (#struct){
+        conf: (#struct){
+          one: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }, (struct){
+              }) }
+          }
+          two: (#struct){
+            shared: (string){ "foo" }
+            disj: (_){ |(*(#struct){
+              }, (_){ _ }) }
+          }
+        }
+      }
+    }
+  }
+}
+-- out/compile --
+--- in.cue
+{
+  reduced: {
+    t1: {
+      S: {
+        if true {
+          a: 〈2;U〉
+        }
+      }
+      x: 〈0;S〉
+      x: {
+        ["a"]: {
+          b: (1|〈2;T〉)
+        }
+        d: {
+          b: 〈2;x〉.a
+        }
+      }
+      T: 1
+      U: {
+        b: (1|1)
+      }
+    }
+  }
+  issue3851: {
+    t1: {
+      #Top: _
+      #Config: {
+        disj: (_|*"default")
+        shared: _
+      }
+      #Schema: {
+        [string]: 〈1;#Config〉
+        if true {
+          one: {
+            shared: "foo"
+          }
+        }
+      }
+      out: 〈0;#Schema〉
+      out: {
+        ["one"]: {
+          disj: (_|〈2;#Top〉)
+        }
+        two: {
+          shared: 〈2;out〉.one.shared
+        }
+      }
+    }
+  }
+  issue3851: {
+    t2: {
+      #Top: _
+      #Config: {
+        disj: (_|*{})
+        shared: _
+      }
+      #Env: {
+        conf: {
+          [string]: 〈2;#Config〉
+        }
+        if true {
+          conf: {
+            one: {
+              shared: "foo"
+            }
+          }
+        }
+      }
+      env1: 〈0;#Env〉
+      [string]: {
+        conf: {
+          ["one"]: {
+            disj: ({}|〈3;#Top〉)
+          }
+        }
+        conf: {
+          two: {
+            shared: 〈2;conf〉.one.shared
+          }
+        }
+      }
+    }
+  }
+}

internal/core/adt/disjunct2.go

@@ -374,7 +374,13 @@ func (n *nodeContext) processDisjunctions() *Bottom {
 
 // crossProduct computes the cross product of the disjuncts of a disjunction
 // with an existing set of results.
-func (n *nodeContext) crossProduct(dst, cross []*nodeContext, dn *envDisjunct, mode runMode) []*nodeContext {
+func (n *nodeContext) crossProduct(dst, cross []*nodeContext, dnp *envDisjunct, mode runMode) []*nodeContext {
+
+	// TODO: the envDisjunct may be overwritten with recursive calls to
+	// disjunction processing. Investigate why this is. For now we copy the
+	// value to make its state effectively immutable.
+	dn := *dnp
+
 	defer n.unmarkDepth(n.markDepth())
 	defer n.unmarkOptional(n.markOptional())