Dots in module path breaks Lua import in a non-bundle compilation

[Renegatto]

Abstract

tstl fails to produce valid lua code from a subset of valid (accordingly to tstl docs) code if ts file names contain dots in paths.

This problem may naturally arise, for example, when compiling from Purescript to JS and then from JS to Lua using tstl.

The example is not the natural use case for tstl, however, the bug is the bug.

Example

Let's say we have two files:
./src/Foo.Bar/index.ts

export const answer: number = 42;

./src/Qux/index.ts

import {answer} from "./Foo.Bar";
export const printAnswer = () => print(answer)

So import {answer} from "./Foo.Bar"; will be compiled (in a non-bundle mode) to

local ____Foo_2EBar = require("Foo.Bar.index")
local answer = ____Foo_2EBar.answer

and lua will be searching at ./Foo/Bar/index.lua" for that module.

That will result an error:

lua: ./Qux/index.lua:3: module 'Foo.Bar.index' not found:
        no field package.preload['Foo.Bar.index']
        no file './Foo/Bar/index.lua'
        no file '/usr/local/share/lua/5.1/Foo/Bar/index.lua'
        no file '/usr/local/share/lua/5.1/Foo/Bar/index/init.lua'
        no file '/usr/local/lib/lua/5.1/Foo/Bar/index.lua'
        no file '/usr/local/lib/lua/5.1/Foo/Bar/index/init.lua'
        no file '/usr/share/lua/5.1/Foo/Bar/index.lua'
        no file '/usr/share/lua/5.1/Foo/Bar/index/init.lua'
        no file './Foo/Bar/index.so'
        no file '/usr/local/lib/lua/5.1/Foo/Bar/index.so'
        no file '/usr/lib/x86_64-linux-gnu/lua/5.1/Foo/Bar/index.so'
        no file '/usr/lib/lua/5.1/Foo/Bar/index.so'
        no file '/usr/local/lib/lua/5.1/loadall.so'
        no file './Foo.so'
        no file '/usr/local/lib/lua/5.1/Foo.so'
        no file '/usr/lib/x86_64-linux-gnu/lua/5.1/Foo.so'
        no file '/usr/lib/lua/5.1/Foo.so'
        no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
        [C]: in function 'require'
        ./Qux/index.lua:3: in main chunk
        [C]: in function 'require'
        ./main.lua:3: in main chunk
        [C]: ?

Soulution

When compiled to a file ./dist/Foo.Bar.Baz/index.lua, split it's name by dots (excluding extension) and put the file into directory ./Foo/Bar/Baz.
This will fix module resolution for lua.
So basically the ts directory

.
├── Foo/
│   └── index.ts
├── Foo.Bar/
│   └── index.ts
├── Foo.Bar.Baz/
│   └── index.ts
├── Qux/
│   └── index.ts
└── index.ts

should be compiled into

.
├── Foo/
│   ├── index.lua
│   └── Bar/
│       └── index.lua
│       └── Baz/
│           └── index.lua
├── Qux/
│   └── index.lua
└── index.lua

instead of

.
├── Foo/
│   └── index.lua
├── Foo.Bar/
│   └── index.lua
├── Foo.Bar.Baz/
│   └── index.lua
├── Qux/
│   └── index.lua
└── index.lua

[Perryvw]

Alternative solution would be to rename the directory Foo.Bar.Baz to something like Foo_dot_Bar_dot_Baz, I have seen Python grpc do something like that.

But I think I prefer your proposed solution of just outputing to nested directories better.

[SamuelRobertBond]

Hey I solved a similar problem for myself by adding an import resolution failure hook in the plugins interface, which allowed me to write a plugin to customize how I solve imports that can't be resolved via the ts resolver. I'm sure it needs some changes to be contributed but let me know what you think. #1455

My specific issue was a file with a . in the name (e.g. physics-api.component.ts)