Lua 5.1 compatibility

[smarek]

• Lua runtime updated syntax for used bitop, lua-struct and lua-utf8 modules
  • inspired from https://github.com/Johnnynator/kaitai_struct_luajit_runtime
• Compiler Lua translator rewritten all bitwise operations to use bit library
• Tests runner updated to run tests with Lua 5.1, with single call change, xpcall in Lua5.1 takes 2 args instead of varargs

This is also related to PR kaitai-io/ci_targets#7

[ildar]

Thanks for an invitation.

1. This PR effectively replaces Lua 5.3 with Lua 5.1. Is this what's intended? Or you wanted dual-Lua compatibility?
2. There's compat-53 library aimed to unify 5.3 features in 5.1 environment. Good for dual-targeting and migration.

[smarek]

@ildar thank you for review

1. yes, i think so
   • given this: Working with Lua 5.2 kaitai_struct_lua_runtime#1 (comment)
   • there should be only one Lua target currently, that is 5.1+ compatible
2. compat library nice, thank you, but it does not have the necessary bitwise operations, so maybe in future

[ildar]

on (2): plz take a look: lunarmodules/lua-compat-5.3@7e2b0b5

[smarek]

oh, so similar to bitop, i'll consider re-working the PR eventually, thank you

would it somehow be even possible to backport the bitwise operators (eg. 1 << 2)
i smell it could be possible in C API maybe, but i'm totally clueless

[ildar]

https://github.com/keplerproject/lua-compat-5.3/blob/master/lbitlib.c#L99

[ildar]

on (1) I just read the whole discussion. I perceive @GreyCat sympathised Dual-lua-targeting, calling it cross-platform-ing later: kaitai-io/kaitai_struct_lua_runtime#1 (comment) I suggest suporting dual/triple-Lua-versions as: 1. it looks like there are users for 5.3, 5.1 and even 5.2 (rare in the Lua community yet demanded because of WShark); 2. it corresponds to current Lua community trends as many Lua libraries are 5.1 and 5.3 compatible (check LuaRocks.org) One added issue to solve is testing: Kaitai would better be tested with all 2 (or 3) Lua versions. But this IMHO could be postponed for a later fix.

[smarek]

Final solution should be compatible 5.1+ and agree, so i'll update ci_targets with matrix of testing for each specific lua version

[smarek]

This PR is closed since the individual submodules will get updated anyway