2.8.2: internal error: missing builtin 'array_bool_xor'

[informarte]

The MiniZinc 2.8.2 compiler has an issue with flattening a ground speck-optimization instance.

Please see the attached archive easy_1.zip for all the files needed to reproduce the issue.

Reproduction steps:

unzip easy_1.zip
cd easy_1
minizinc solution.mzn easy_1.dzn

yields

Error: evaluation error: internal error: missing builtin 'array_bool_xor'
.../easy_1/SPECK-Optimisation.mzn:32.12-35.1
  in call 'forall'
  in array comprehension expression
    with i = 0
.../easy_1/SPECK-Optimisation.mzn:33.5-34.59
  in binary '/\' operator expression
.../easy_1/SPECK-Optimisation.mzn:34.5-59
  in binary '=' operator expression
.../MiniZincIDE-2.8.2-bundle-linux-x86_64/share/minizinc/std/stdlib/stdlib_compare.mzn:292.3-296.50
  in binary '/\' operator expression
.../MiniZincIDE-2.8.2-bundle-linux-x86_64/share/minizinc/std/stdlib/stdlib_compare.mzn:293.5-296.50
  in let expression
.../MiniZincIDE-2.8.2-bundle-linux-x86_64/share/minizinc/std/stdlib/stdlib_compare.mzn:296.10-50
  in call 'forall'
  in array comprehension expression
    with i = <expression>
  in binary '=' operator expression
  in binary '=' operator expression
.../MiniZincIDE-2.8.2-bundle-linux-x86_64/share/minizinc/std/stdlib/stdlib_logic.mzn:97.3-28
  in call 'array_bool_xor'

Flattening for OR Tools gives the same error message, flattening for Chuffed works.

The solution consists of four assignments, among them to L and R. Omitting the assignment to R solves the issue. Omitting the assignment to L causes another issue:

Error: evaluation error: cannot evaluate expression 'X_INTRODUCED_465_'