Add test case for #1323

[trdthg]

add testcase for #1323

I added two same test files, one is placed in the typecheck directory and the other in the c directory

type regidx_range('n) = 'n <= 1 & 'n >= 0

newtype regidx('n), regidx_range('n) = Regidx : int('n)

type s_regidx = { 'n, regidx_range('n) . regidx('n) }

mapping int_string : int <-> string = {
  0 <-> "0",
  1 <-> "1",
}

mapping encdec_reg : s_regidx <-> string = { 
  Regidx(r) <-> int_string(r),
}

@Alasdair you can see only the one in c folder failed

[github-actions]

Test Results

   13 files     28 suites   0s ⏱️
  879 tests   878 ✅ 0 💤 0 ❌  1 🔥
4 078 runs  4 064 ✅ 0 💤 0 ❌ 14 🔥

For more details on these errors, see this check.

Results for commit 85aff95.