multiple assignment statements (see #754) still a problem in 0.555 ?

[SteveDE]

Merged to 0.555 and I'm afraid it is still not ordering correctly re: #754

Pulled down 0.555 luau windows binary and ran with luau --compile BinarySearch.lua > Result.text

   30:                 tfound[1],num = num,num - 1
SUBK R11 R10 K4
SETTABLEN R10 R9 1

If the assignments are not done using multiple assignment the order is correct and the search works

   39:                 tfound[1] = num
39: SETTABLEN R10 R9 1
   40:                 num = num - 1
40: SUBK R10 R10 K13

BinarySearch.zip

[SteveDE]

Digging more, I see an added move, but my test harness died in the same spot.

   30:                 tfound[1],num = num,num - 1
SUBK R11 R10 K4
SETTABLEN R10 R9 1
MOVE R10 R11

vs sep line assign

   30:                 tfound[1] = num
SETTABLEN R10 R9 1
   31:                 num = num - 1
SUBK R10 R10 K4

[vegorov-rbx]

Ordering is correct in both cases, in first case SUBK writes result into R11 that doesn't conflict with R10.
Execution result of your sample is the same in both versions.

Meta-method execution order inside multiple assignment statement is not guaranteed.

[SteveDE]

Bitten by LUAU_FASTFLAGVARIABLE(LuauMultiAssignmentConflictFix, false)
Stock compile as library needs this flag changed or set at runtime

[vegorov-rbx]

Yeah, unfortunately we don't have the flag system described in the documentation right now.
It's something we have to improve.