New option recompileLuaLib: Recompile the Lua standard library with custom plugins. #1656

pilaoda · 2025-08-23T16:58:44Z

Implementation about #1478 #1502
all luaLibImport options are supported.

…ustom plugins.

Perryvw

I don't understand how this relates to #1478, nothing has changed there, has it?

wrt #1502, the idea is the user can supply their own lualib implementation, I'm not sure simply recompiling the existing lualib with plugins is what we're after. If I wanted to completely replace a lualib file how would I do it?

I'm not sure what the reason would be for wanting this recompilation mechanism?

Perryvw · 2025-08-23T18:28:55Z

src/transpilation/transpile.ts

        transpiledFiles = [];
    }

+    const proxyEmitHost =


I don't understand what this does or why it's needed

Because we write lualib_module_info.json when we recompile lualib_bundle.lua, this proxy make sure we don't overwrite the exists one, but collect by our recompile instance.

Couldn't you solve this in lualib.ts where you start the new transpile (with this explanation as comment because code is very hard to understand), instead of here in the global transpile process?

Perryvw · 2025-08-23T18:38:01Z

src/LuaLib.ts

+    feature: LuaLibFeature,
+    luaTarget: LuaTarget,
+    emitHost: EmitHost,
+    useCache = true


I don't get what the point of this getCache in these functions is, why would we no longer want the cache? In my mind either we read from disk or we recompile, but either way we want to cache the result there.

Because every time we recompile, we need new fresh LuaLib code.

I still don't understand this: Either we read the file from disk and we want to cache the data we read, or we recompile and we want to cache the compilation result. Why would we ever want to skip the cache in either case? I don't see why the lualib would change after first compilation within a single tstl run

pilaoda · 2025-08-23T18:56:37Z

#1502, I explain that, user may want to recompile # into Len() in all files including LuaLib.
also in #1478, with this option, every try include in Promise can be compiled into xpcall.
in #535, user can compile all array in LuaLib to Array.New()

all of these 3 issuss can be perfectly resolve by this recompileLuaLib option.

pilaoda · 2025-08-23T19:01:44Z

I write so many plugins and copy tons of code in tstl just to cover every array usage in LuaLib, now I decide to support recompile LuaLib to free me from such troubles

pilaoda · 2025-08-24T10:48:05Z

Here we have 2 user cases:

If I wanted to completely replace a lualib file how would I do it?

Proposal: Lualib override plugins #973

if I just want plugins can also apply to LuaLib Compilation,

Explore marking arrays with a metatable #535, Consider using xpcall in try block #1478, Support recompile lualib with custom plugin? #1502

with proposal in #973: lualib?: Partial<Record<LuaLibFeature, string>>

for user case 1
- it's straightforward and maintainable
- you maintain lua code without type-safety.
for user case 2
- it would be very bother to rewrite all of those LuaLib implentation.
- It's Not Maintainable and no type-safety.

with this option: recompileLuaLib

for user case 1
- you can achive this with a plugin detect and replace the lualib function. this option just let you copy your replacement into a plugin.
- it's maintainable, support typescript.

const plugin: tstl.Plugin = {
  beforeEmit(program: ts.Program, options: tstl.CompilerOptions, emitHost: tstl.EmitHost, result: tstl.EmitFile[]) {
    for (const file of result) {
     if (file.outputPath == "xxx/lualib/Class") {
      file.code = "local MyCustomClass = {};";
      // or compile typescript
      file.code = tstl.transpileString("const MyCustomClass = {};", options).file!.lua!;
     }
    }
  },
};

for user case 2
- it's straightforward and maintainable

Sorry I don't make those pro and con very clear last night, hope I done it now.

pilaoda · 2025-08-24T18:01:09Z

I realized that I had made a mistake about #1478. The implementation of Promise does not use try, but instead uses pcall.
My memory is jumbled, hahaha.

However, this does not affect #535 and #1502 related to Array that need this option.

src/CompilerOptions.ts

Perryvw · 2025-08-25T12:16:30Z

src/LuaLib.ts

+    feature: LuaLibFeature,
+    luaTarget: LuaTarget,
+    emitHost: EmitHost,
+    useCache = true


I still don't understand this: Either we read the file from disk and we want to cache the data we read, or we recompile and we want to cache the compilation result. Why would we ever want to skip the cache in either case? I don't see why the lualib would change after first compilation within a single tstl run

test/transpile/lualib.spec.ts

Perryvw · 2025-08-25T12:20:59Z

test/transpile/lualib.spec.ts

+        .expectToHaveNoDiagnostics()
+        .getLuaResult();
+    const lualubBundle = transpiledFiles.find(f => path.basename(f.outPath) === "lualib_bundle.lua");
+    expect(lualubBundle?.lua).toContain(


Could you also add a test with bundling?

Perryvw · 2025-08-25T12:24:40Z

src/transpilation/transpile.ts

        transpiledFiles = [];
    }

+    const proxyEmitHost =


Couldn't you solve this in lualib.ts where you start the new transpile (with this explanation as comment because code is very hard to understand), instead of here in the global transpile process?

add test LuaLib recompile with bundling option.

new option recompileLuaLib: Recompile the Lua standard library with c…

ae668e1

…ustom plugins.

Perryvw reviewed Aug 23, 2025

View reviewed changes

pilaoda added 2 commits August 24, 2025 17:11

fix declaration

dd428ba

fix LuaLib module resolution.

4424e02

pilaoda marked this pull request as draft August 24, 2025 14:09

add skipRecompileLuaLib option for plugin.

d0ac73b

pilaoda marked this pull request as ready for review August 24, 2025 14:43

Perryvw reviewed Aug 25, 2025

View reviewed changes

add assert about lualib_bundle.lua outpath.

2efb99c

add test LuaLib recompile with bundling option.

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New option recompileLuaLib: Recompile the Lua standard library with custom plugins. #1656

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New option recompileLuaLib: Recompile the Lua standard library with custom plugins. #1656

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pilaoda commented Aug 23, 2025

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pilaoda commented Aug 24, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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with proposal in #973: lualib?: Partial<Record<LuaLibFeature, string>>

with this option: recompileLuaLib

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pilaoda commented Aug 24, 2025

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