internal/core/adt: disable structure sharing for pending arcs

Theoretically this is still possible, but CUE
does not handle this properly at
this moment.

We disable it with and add a TODO.

Besides fixing 3849, this brings V3 more in
line with V2 for several other tests.

Fixes #3849

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: Idb9f73d9f83cd868230fb298214bdaf289bfb632
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1212316
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

Author: mpvl

Diff for: cue/testdata/comprehensions/pushdown.txtar

@@ -939,6 +939,8 @@ issue3729.withoutDisjunction.root.#sub1.#sub2: conflicting values null and {#sub
     ./issue3729.cue:11:9
 noStackOverflowStructCycle.#list.tail: structural cycle
 noStackOverflowStructCycle.list.tail: structural cycle
+provideIncompleteSuccess.t2.a.c.d: field not allowed:
+    ./in.cue:203:8
 structShare.err1.x.d.e: field not allowed:
     ./in.cue:591:9
 fieldMismatch.a: cannot combine regular field "x" with 2:
@@ -1099,7 +1101,8 @@ Result:
       // [structural cycle] noStackOverflowStructCycle.list.tail: structural cycle
     }
   }
-  provideIncompleteSuccess: (struct){
+  provideIncompleteSuccess: (_|_){
+    // [eval]
     t1: (struct){
       #a: (_|_){
         // [incomplete] provideIncompleteSuccess.t1.#a: incomplete bool: bool:
@@ -1112,15 +1115,22 @@ Result:
       }
       y: ~(provideIncompleteSuccess.t1.x)
     }
-    t2: (struct){
+    t2: (_|_){
+      // [eval]
       #a: (#struct){
         c: (int){ 4 }
         b: (bool){ true }
       }
       #c: (#struct){
       }
-      a: (struct){
-        c: (#struct){
+      a: (_|_){
+        // [eval]
+        c: (_|_){
+          // [eval]
+          d: (_|_){
+            // [eval] provideIncompleteSuccess.t2.a.c.d: field not allowed:
+            //     ./in.cue:203:8
+          }
         }
         b: (bool){ true }
       }
@@ -1773,7 +1783,7 @@ Result:
 diff old new
 --- old
 +++ new
-@@ -1,39 +1,17 @@
+@@ -1,39 +1,19 @@
  Errors:
  embed.fail1.p: field not allowed:
 -    ./in.cue:37:9
@@ -1801,10 +1811,10 @@ diff old new
      ./issue3729.cue:11:9
  noStackOverflowStructCycle.#list.tail: structural cycle
  noStackOverflowStructCycle.list.tail: structural cycle
--provideIncompleteSuccess.t2.a.c.d: field not allowed:
+ provideIncompleteSuccess.t2.a.c.d: field not allowed:
 -    ./in.cue:200:7
 -    ./in.cue:202:4
--    ./in.cue:203:8
+     ./in.cue:203:8
 -    ./in.cue:208:7
  structShare.err1.x.d.e: field not allowed:
 -    ./in.cue:588:15
@@ -1813,7 +1823,7 @@ diff old new
      ./in.cue:591:9
  fieldMismatch.a: cannot combine regular field "x" with 2:
      ./in.cue:152:7
-@@ -79,8 +57,8 @@
+@@ -79,8 +59,8 @@
    }
    fail: (struct){
      a: (_|_){
@@ -1824,7 +1834,7 @@ diff old new
      }
    }
    embed: (_|_){
-@@ -89,10 +67,6 @@
+@@ -89,10 +69,6 @@
        // [eval]
        p: (_|_){
          // [eval] embed.fail1.p: field not allowed:
@@ -1835,7 +1845,7 @@ diff old new
          //     ./in.cue:46:4
          //     ./in.cue:49:9
        }
-@@ -121,12 +95,11 @@
+@@ -121,12 +97,11 @@
        // [eval]
        p: (_|_){
          // [eval] embed.fail4.p: field not allowed:
@@ -1852,17 +1862,7 @@ diff old new
        }
      }
      #C4: (#struct){
-@@ -198,8 +171,7 @@
-       // [structural cycle] noStackOverflowStructCycle.list.tail: structural cycle
-     }
-   }
--  provideIncompleteSuccess: (_|_){
--    // [eval]
-+  provideIncompleteSuccess: (struct){
-     t1: (struct){
-       #a: (_|_){
-         // [incomplete] provideIncompleteSuccess.t1.#a: incomplete bool: bool:
-@@ -207,16 +179,12 @@
+@@ -207,13 +182,10 @@
          b: (bool){ bool }
        }
        x: (#struct){
@@ -1873,39 +1873,25 @@ diff old new
 -        c: (int){ 4 }
 -        b: (bool){ true }
 -      }
--    }
--    t2: (_|_){
--      // [eval]
 +        b: (bool){ true }
 +        c: (int){ 4 }
 +      }
 +      y: ~(provideIncompleteSuccess.t1.x)
-+    }
-+    t2: (struct){
-       #a: (#struct){
-         c: (int){ 4 }
-         b: (bool){ true }
-@@ -223,17 +191,8 @@
-       }
-       #c: (#struct){
-       }
--      a: (_|_){
--        // [eval]
--        c: (_|_){
--          // [eval]
--          d: (_|_){
--            // [eval] provideIncompleteSuccess.t2.a.c.d: field not allowed:
+     }
+     t2: (_|_){
+       // [eval]
+@@ -229,10 +201,7 @@
+           // [eval]
+           d: (_|_){
+             // [eval] provideIncompleteSuccess.t2.a.c.d: field not allowed:
 -            //     ./in.cue:200:7
 -            //     ./in.cue:202:4
--            //     ./in.cue:203:8
+             //     ./in.cue:203:8
 -            //     ./in.cue:208:7
--          }
-+      a: (struct){
-+        c: (#struct){
+           }
          }
          b: (bool){ true }
-       }
-@@ -263,9 +222,22 @@
+@@ -263,9 +232,22 @@
    }
    cyclicError: (struct){
      a: (_|_){
@@ -1931,7 +1917,7 @@ diff old new
      }
    }
    midwayReferences: (struct){
-@@ -279,24 +251,9 @@
+@@ -279,24 +261,9 @@
          }
        }
      }
@@ -1959,7 +1945,7 @@ diff old new
    }
    closedCheck: (struct){
      success1: (struct){
-@@ -399,13 +356,7 @@
+@@ -399,13 +366,7 @@
            }
          }
        }
@@ -1974,7 +1960,7 @@ diff old new
        #F: (#struct){
          e: (bool){ bool }
          f: (_|_){
-@@ -422,17 +373,11 @@
+@@ -422,17 +383,11 @@
          }
        }
        E: (_|_){
@@ -1993,7 +1979,7 @@ diff old new
        }
      }
      derefDisj2: (struct){
-@@ -443,17 +388,11 @@
+@@ -443,17 +398,11 @@
          }
        }
        E: (_|_){
@@ -2012,7 +1998,7 @@ diff old new
        }
      }
      bulk1: (struct){
-@@ -576,9 +515,6 @@
+@@ -576,9 +525,6 @@
            // [eval]
            e: (_|_){
              // [eval] structShare.err1.x.d.e: field not allowed:
@@ -2022,7 +2008,7 @@ diff old new
              //     ./in.cue:591:9
            }
          }
-@@ -602,13 +538,13 @@
+@@ -602,13 +548,13 @@
        }
        envs: (struct){
          e1: (#struct){
@@ -2040,7 +2026,7 @@ diff old new
          }
        }
      }
-@@ -645,9 +581,8 @@
+@@ -645,9 +591,8 @@
      _c: (struct){
        y: (int){ 1 }
      }
@@ -2052,7 +2038,7 @@ diff old new
      }
    }
    errorPropagation: (_|_){
-@@ -705,10 +640,10 @@
+@@ -705,10 +650,10 @@
        }
        foo: (#struct){
          kind: (string){ "foo" }
@@ -2065,7 +2051,7 @@ diff old new
        }
      }
      regular: (_|_){
-@@ -721,16 +656,11 @@
+@@ -721,16 +666,11 @@
        foo: (_|_){
          // [eval]
          kind: (string){ "foo" }
@@ -2084,7 +2070,7 @@ diff old new
          }
        }
      }
-@@ -742,10 +672,10 @@
+@@ -742,10 +682,10 @@
        }
        foo: (#struct){
          kind: (string){ "foo" }
@@ -2097,15 +2083,15 @@ diff old new
        }
      }
    }
-@@ -816,7 +746,6 @@
+@@ -816,7 +756,6 @@
        root: (_|_){
          // [eval] issue3729.withoutDisjunction.root.#sub1.#sub2: conflicting values null and {#sub1?:{#sub2:true}} (mismatched types null and struct):
          //     ./issue3729.cue:9:9
 -        //     ./issue3729.cue:10:2
          //     ./issue3729.cue:11:9
          #sub1?: (#struct){
            #sub2: (bool){ true }
-@@ -850,12 +779,7 @@
+@@ -850,12 +789,7 @@
              #sub2?: (bool){ bool }
            }
          }
@@ -2119,7 +2105,7 @@ diff old new
              #sub1?: (#struct){
                #sub2: (bool){ true }
              }
-@@ -864,14 +788,7 @@
+@@ -864,14 +798,7 @@
      }
      full: (struct){
        #Application: (#struct){
@@ -2136,15 +2122,15 @@ diff old new
        #ApplicationSpec: (#struct){
          syncPolicy?: ((null|struct)){ |((null){ null }, (#struct){
 -- out/evalalpha/stats --
-Leaks:  620
+Leaks:  636
 Freed:  0
 Reused: 0
-Allocs: 620
+Allocs: 636
 Retain: 0
 
-Unifications: 570
-Conjuncts:    943
-Disjuncts:    28
+Unifications: 578
+Conjuncts:    965
+Disjuncts:    32
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -2155,18 +2141,18 @@ diff old new
 -Reused: 510
 -Allocs: 71
 -Retain: 107
-+Leaks:  620
++Leaks:  636
 +Freed:  0
 +Reused: 0
-+Allocs: 620
++Allocs: 636
 +Retain: 0
 
 -Unifications: 545
 -Conjuncts:    870
 -Disjuncts:    641
-+Unifications: 570
-+Conjuncts:    943
-+Disjuncts:    28
++Unifications: 578
++Conjuncts:    965
++Disjuncts:    32
 -- out/eval/stats --
 Leaks:  63
 Freed:  518
@@ -2177,9 +2163,6 @@ Retain: 107
 Unifications: 545
 Conjuncts:    870
 Disjuncts:    641
--- diff/todo/p2 --
-provideIncompleteSuccess.t2.a.c.d: missing error: probably correct.
-   A bit esoteric, but should probably work.
 -- diff/explanation --
 cyclicError: improved error message.
 nestedWithDynamicFieldOK: fixed bug.