If the 'string' module is required into elided code, generated C doesn't define nelua_nlstring___eq

Bug description

I wrote a library with a function-localized require 'string', used that library, and then didn't use the function with the require. The resulting code failed to compile with a C compiler error.

Code example

-- require 'string' -- fix #1: uncomment
local function f()
  local ss = require 'string' -- fix #2: comment
end

local function g()
  return "a" == "b"
end

-- f() -- fix #3: uncomment
print(g())

Current behavior

$ nelua stringeq.nelua
/home/jfondren/.cache/nelua/stringeq.c: In function 'stringeq_g':
/home/jfondren/.cache/nelua/stringeq.c:94:10: error: implicit declaration of function 'nelua_nlstring___eq' [-Werror=implicit-function-declaration]
   94 |   return nelua_nlstring___eq(((nlstring){(uint8_t*)"a", 1}), ((nlstring){(uint8_t*)"b", 1}));
      |          ^~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
error: C compilation for '/home/jfondren/.cache/nelua/stringeq' failed

Related example

I ran into another surprising effect from requiring 'string', and also thought it was a bug for a while:

local s1 <comptime> = 'a' .. 'b'

require 'string'

local s2 <comptime> = 'b' .. 'c'

Error:

stringcat.nelua:1:1: from: AST node Block
local s1 <comptime> = 'a' .. 'b'
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
stringcat.nelua:5:7: error: compile time variables can only assign to compile time expressions
local s2 <comptime> = 'b' .. 'c'
      ^~~~~~~~~~~~~

The easy workaround was to have lua do that:

local s1 <comptime> = #['a' .. 'b']#

require 'string'

local s2 <comptime> = #['b' .. 'c']#

Non-complaint

That Lua's involved in the compilation process is a strength of Nelua, so I accept that requiring a library can have apparently strange effects like the previous one. Even C compiler errors are reasonable when the library has ## linklib 'does-not-exist'.

Environment

arm64 linux Nelua 0.2.0-dev Build number: 1588 Git date: 2023-09-16 16:20:44 -0300 Git hash: 596fcca5c77932da8a07c249de59a9dff3099495 Semantic version: 0.2.0-dev.1588+596fcca5 Copyright (C) 2019-2022 Eduardo Bart (https://nelua.io/)

edubart / nelua-lang