internal/core/adt: carry over enclosing scope

This fixes a case where a nested reference to
a definition within an embedding was still
enforced.

Disabling this is quite tricky, as there are
very similar cases where the user would still
expect the reference to be enforced. A lot of
CUE depends on this. This shows the limitations
of the current closedness algorithm.

As we plan to move to a simpler model anyway,
we introduce some hacky solution that hopefully
will suffice for now.

Fixes #3920

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I5859a50682dad79360b060ee8fb330c064baee65
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1214849
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

Author: mpvl

cue/testdata/benchmarks/issue3633.txtar

@@ -10,8 +10,8 @@ Unifications: 537
 Conjuncts:    2338
 Disjuncts:    1745
 
-CloseIDElems: 2107
-NumCloseIDs: 53
+CloseIDElems: 1249
+NumCloseIDs: 55
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -34,8 +34,8 @@ diff old new
 +Conjuncts:    2338
 +Disjuncts:    1745
 +
-+CloseIDElems: 2107
-+NumCloseIDs: 53
++CloseIDElems: 1249
++NumCloseIDs: 55
 -- out/eval/stats --
 Leaks:  0
 Freed:  3595

cue/testdata/cycle/builtins.txtar

@@ -265,8 +265,8 @@ Unifications: 399
 Conjuncts:    731
 Disjuncts:    38
 
-CloseIDElems: 116
-NumCloseIDs: 189
+CloseIDElems: 150
+NumCloseIDs: 191
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -291,8 +291,8 @@ diff old new
 +Conjuncts:    731
 +Disjuncts:    38
 +
-+CloseIDElems: 116
-+NumCloseIDs: 189
++CloseIDElems: 150
++NumCloseIDs: 191
 -- out/eval/stats --
 Leaks:  25
 Freed:  446

cue/testdata/cycle/chain.txtar

@@ -1705,7 +1705,7 @@ Unifications: 931
 Conjuncts:    4994
 Disjuncts:    1615
 
-CloseIDElems: 20288
+CloseIDElems: 19418
 NumCloseIDs: 1535
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
@@ -1731,7 +1731,7 @@ diff old new
 +Conjuncts:    4994
 +Disjuncts:    1615
 +
-+CloseIDElems: 20288
++CloseIDElems: 19418
 +NumCloseIDs: 1535
 -- out/eval/stats --
 Leaks:  56

cue/testdata/cycle/inline.txtar

@@ -405,8 +405,8 @@ Unifications: 253
 Conjuncts:    639
 Disjuncts:    0
 
-CloseIDElems: 329
-NumCloseIDs: 229
+CloseIDElems: 363
+NumCloseIDs: 231
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -431,8 +431,8 @@ diff old new
 +Conjuncts:    639
 +Disjuncts:    0
 +
-+CloseIDElems: 329
-+NumCloseIDs: 229
++CloseIDElems: 363
++NumCloseIDs: 231
 -- out/eval/stats --
 Leaks:  286
 Freed:  253

cue/testdata/definitions/issue3834.txtar

@@ -69,8 +69,8 @@ Unifications: 171
 Conjuncts:    322
 Disjuncts:    48
 
-CloseIDElems: 1232
-NumCloseIDs: 64
+CloseIDElems: 1109
+NumCloseIDs: 88
 -- diff/-out/evalalpha/stats<==>+out/eval/stats --
 diff old new
 --- old
@@ -95,8 +95,8 @@ diff old new
 +Conjuncts:    322
 +Disjuncts:    48
 +
-+CloseIDElems: 1232
-+NumCloseIDs: 64
++CloseIDElems: 1109
++NumCloseIDs: 88
 -- out/eval/stats --
 Leaks:  24
 Freed:  207