internal/core/adt: disable prep for associative lists

This preparation is currently causing significant
performance issues. As it is not used, we disable it
for now.

The issue follows from the following:
1) the list type can (currently) only be known after
    the last conjunct is processed.
2) lists are not processed until the list type is known
3) this means that lists are not processed and added
    to the disjunct for any but the last disjunction
4) this means that disjuncts with the same list cannot
     be compared and are not prematurely eliminated.

There are many possible ways to fix this. For instance,
1) we could first evaluate disjuncts, before taking
   their cross product, to determine what the list
   type will be.
2) as we only care about equality, we could anyway
    evaluate lists, and compare lists collected so far
    based on equality. This can especially be fast
    when we have a fast equality check.

For now we just disable the state.

This change exposes another issue: basically, if
evaluated in the right order, a closedContext.Expr
may be non-nil if a struct is not closed. The
resulting panic is just to catch an optimization.
This will be easier to fix once we support the
same semantics for lists as we have for structs.
So for now, we just disable the check.

Note that this causes some error messages to
now mention a "cycle error", which is indicative
of displaying an unevaluated value. We will worry
about that later. It is not material for the result.

Issue #2850

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I11df185bb5d3747e72c3ca2888ee4dd7cce70d47
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1204490
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Matthew Sackman <[email protected]>

cue/testdata/benchmarks/disjunctelim.txtar

@@ -26,15 +26,15 @@ list: [1] | [2] | [3] | [4] // 184 conjuncts; 84  disjuncts (+33; +16)
 list: [1] | [2] | [3] | [4] // 217 conjuncts; 100 disjuncts (+33; +16)
 
 -- out/evalalpha/stats --
-Leaks:  25997
-Freed:  16398
-Reused: 16398
-Allocs: 25997
+Leaks:  182
+Freed:  90
+Reused: 90
+Allocs: 182
 Retain: 0
 
-Unifications: 4115
-Conjuncts:    71139
-Disjuncts:    21882
+Unifications: 20
+Conjuncts:    327
+Disjuncts:    138
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -44,18 +44,18 @@ diff old new
 -Freed:  269
 -Reused: 258
 -Allocs: 11
-+Leaks:  25997
-+Freed:  16398
-+Reused: 16398
-+Allocs: 25997
++Leaks:  182
++Freed:  90
++Reused: 90
++Allocs: 182
  Retain: 0
 
 -Unifications: 131
 -Conjuncts:    755
 -Disjuncts:    269
-+Unifications: 4115
-+Conjuncts:    71139
-+Disjuncts:    21882
++Unifications: 20
++Conjuncts:    327
++Disjuncts:    138
 -- out/eval/stats --
 Leaks:  0
 Freed:  269

cue/testdata/benchmarks/listdedup.txtar

@@ -33,14 +33,14 @@ C: #steps: #Script & {mount: [B]}
 
 #ref: {a: 1} | {b: 2}
 -- out/evalalpha/stats --
-Leaks:  163
+Leaks:  158
 Freed:  10
 Reused: 10
-Allocs: 163
+Allocs: 158
 Retain: 0
 
-Unifications: 53
-Conjuncts:    407
+Unifications: 56
+Conjuncts:    461
 Disjuncts:    40
 -- out/evalalpha --
 (struct){
@@ -545,17 +545,17 @@ diff old new
 -Reused: 24051
 -Allocs: 45
 -Retain: 1
-+Leaks:  163
++Leaks:  158
 +Freed:  10
 +Reused: 10
-+Allocs: 163
++Allocs: 158
 +Retain: 0
 
 -Unifications: 18724
 -Conjuncts:    100730
 -Disjuncts:    24097
-+Unifications: 53
-+Conjuncts:    407
++Unifications: 56
++Conjuncts:    461
 +Disjuncts:    40
 -- out/eval/stats --
 Leaks:  0

cue/testdata/cycle/comprehension.txtar

@@ -310,14 +310,14 @@ issue2367: {
 }
 
 -- out/evalalpha/stats --
-Leaks:  775
+Leaks:  778
 Freed:  63
 Reused: 63
-Allocs: 775
+Allocs: 778
 Retain: 0
 
-Unifications: 495
-Conjuncts:    3328
+Unifications: 498
+Conjuncts:    3349
 Disjuncts:    196
 -- out/evalalpha --
 Errors:
@@ -431,14 +431,15 @@ Result:
       }
     }
     list: (struct){
-      panels: (_|_){
-        // [incomplete] selfReferential.list.panels: cannot range over panels (incomplete type _):
-        //     ./in.cue:103:15
+      panels: (#list){
         0: (struct){
+          id: (int){ 0 }
         }
         1: (struct){
+          id: (int){ 1 }
         }
         2: (struct){
+          id: (int){ 2 }
         }
       }
     }
@@ -779,26 +780,7 @@ diff old new
          }
        }
      }
-@@ -112,15 +109,14 @@
-       }
-     }
-     list: (struct){
--      panels: (#list){
-+      panels: (_|_){
-+        // [incomplete] selfReferential.list.panels: cannot range over panels (incomplete type _):
-+        //     ./in.cue:103:15
-         0: (struct){
--          id: (int){ 0 }
-         }
-         1: (struct){
--          id: (int){ 1 }
-         }
-         2: (struct){
--          id: (int){ 2 }
-         }
-       }
-     }
-@@ -127,9 +123,9 @@
+@@ -127,9 +124,9 @@
      insertionError: (_|_){
        // [eval]
        A: (_|_){
@@ -810,7 +792,7 @@ diff old new
        }
      }
      acrossOr: (struct){
-@@ -268,13 +264,17 @@
+@@ -268,13 +265,17 @@
                reject: (string){ string }
              }, (#struct){
                resource: (string){ string }
@@ -835,7 +817,7 @@ diff old new
          }) }
      }
      p2: (struct){
-@@ -328,7 +328,8 @@
+@@ -328,7 +329,8 @@
        }
      }
    }
@@ -845,7 +827,7 @@ diff old new
      t1: (struct){
        p1: (struct){
          D: (struct){
-@@ -361,35 +362,28 @@
+@@ -361,35 +363,28 @@
          }
        }
      }
@@ -913,17 +895,17 @@ diff old new
 -Reused: 1260
 -Allocs: 60
 -Retain: 145
-+Leaks:  775
++Leaks:  778
 +Freed:  63
 +Reused: 63
-+Allocs: 775
++Allocs: 778
 +Retain: 0
 
 -Unifications: 832
 -Conjuncts:    2525
 -Disjuncts:    1404
-+Unifications: 495
-+Conjuncts:    3328
++Unifications: 498
++Conjuncts:    3349
 +Disjuncts:    196
 -- out/eval/stats --
 Leaks:  50
@@ -938,7 +920,6 @@ Disjuncts:    1404
 -- diff/explanation --
 B.a.children: now correctly marked as incomplete
 -- diff/todo/p0 --
-selfReferential.list.panels: invalid incomplete error: related to "or" builtin
 siblingInsertion.t2: errors
 -- diff/todo/p2 --
 issue1881.#AllOutputs.retry: additional entry.

cue/testdata/cycle/issue494.txtar

@@ -35,10 +35,8 @@ Conjuncts:    83
 Disjuncts:    45
 -- out/evalalpha --
 Errors:
-f.ben: incompatible list lengths (1 and 2):
-    ./in.cue:20:17
-g.ben: incompatible list lengths (1 and 2):
-    ./in.cue:23:17
+f.ben: incompatible list lengths (1 and 2)
+g.ben: incompatible list lengths (1 and 2)
 
 Result:
 (_|_){
@@ -93,17 +91,15 @@ Result:
   f: (_|_){
     // [eval]
     ben: (_|_){
-      // [eval] f.ben: incompatible list lengths (1 and 2):
-      //     ./in.cue:20:17
+      // [eval] f.ben: incompatible list lengths (1 and 2)
       0: (struct){
       }
     }
   }
   g: (_|_){
     // [eval]
     ben: (_|_){
-      // [eval] g.ben: incompatible list lengths (1 and 2):
-      //     ./in.cue:23:17
+      // [eval] g.ben: incompatible list lengths (1 and 2)
       0: (struct){
       }
       1: (struct){
@@ -115,18 +111,7 @@ Result:
 diff old new
 --- old
 +++ new
-@@ -1,6 +1,8 @@
- Errors:
--f.ben: incompatible list lengths (1 and 2)
--g.ben: incompatible list lengths (1 and 2)
-+f.ben: incompatible list lengths (1 and 2):
-+    ./in.cue:20:17
-+g.ben: incompatible list lengths (1 and 2):
-+    ./in.cue:23:17
-
- Result:
- (_|_){
-@@ -41,13 +43,7 @@
+@@ -41,13 +41,7 @@
        }
      }
    }
@@ -141,32 +126,22 @@ diff old new
    e: (struct){
      ben: (#list){
        0: (struct){
-@@ -61,12 +57,9 @@
-   f: (_|_){
-     // [eval]
+@@ -63,10 +57,6 @@
      ben: (_|_){
--      // [eval] f.ben: incompatible list lengths (1 and 2)
--      0: (struct){
+       // [eval] f.ben: incompatible list lengths (1 and 2)
+       0: (struct){
 -        pos: (int){ 0 }
 -      }
 -      1: (struct){
 -        pos: (int){ 1 }
-+      // [eval] f.ben: incompatible list lengths (1 and 2):
-+      //     ./in.cue:20:17
-+      0: (struct){
        }
      }
    }
-@@ -73,9 +66,9 @@
-   g: (_|_){
-     // [eval]
+@@ -75,7 +65,6 @@
      ben: (_|_){
--      // [eval] g.ben: incompatible list lengths (1 and 2)
--      0: (struct){
+       // [eval] g.ben: incompatible list lengths (1 and 2)
+       0: (struct){
 -        pos: (int){ 0 }
-+      // [eval] g.ben: incompatible list lengths (1 and 2):
-+      //     ./in.cue:23:17
-+      0: (struct){
        }
        1: (struct){
        }