feat: embed SWC TypeScript transpiler and load .ts modules directly#226
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benpalevsky wants to merge 1 commit into
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feat: embed SWC TypeScript transpiler and load .ts modules directly#226benpalevsky wants to merge 1 commit into
benpalevsky wants to merge 1 commit into
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Compiles a Rust staticlib (transpiler-ffi/) built around SWC and exposed through a minimal two-function/one-struct C FFI, wired into the engine via SCsub. jsb_module_resolver loads .ts sources directly by transpiling them in-process into the CommonJS module wrapper, so TypeScript no longer needs a separate tsc emit step to run. Opt-in via a new use_typescript_transpiler build flag, off by default. With the flag off (the default) no Rust toolchain enters the build graph and every .ts code path is compiled out behind JSB_WITH_TYPESCRIPT_TRANSPILER: script loading keeps using the tsc-emitted .js (convert_typescript_path), the resolver does not probe .ts, and the build behaves as before this change. The FFI is panic-safe (catch_unwind at the boundary) and hands buffers to C through Box<[u8]> so the C-side free is sound. Build flags in SCsub allow the staticlib's libstd symbols to coexist with Godot's prebuilt accesskit staticlib on Linux/Windows.
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Part 1 of 3 — the SWC stack. Foundation; PRs 227 and 228 build on this one.
Problem
Today, a
.tsfile has to be compiled to.jsbytscbefore GodotJS can run it. That means a separate build step and a dependency on having TypeScript installed.What this adds
An embedded TypeScript transpiler, so the engine can load
.tsmodules directly. A small Rust library (SWC, a fast TypeScript-to-JavaScript compiler) is built into the engine and called through a tiny interface — two C functions and one struct. When a.tsmodule loads, it's transpiled in-process and run, with no separatetscstep.It is opt-in and off by default: the transpiler only builds with
scons use_typescript_transpiler=yes. With the flag off (the default), no Rust toolchain is needed and the build is unchanged from today.The pieces:
transpiler-ffi/— the Rust staticlib and its C header (the two-function/one-struct boundary).SCsub/config.py— theuse_typescript_transpilerbuild flag (default off), and building/linking the staticlib when it's on.bridge/jsb_module_resolver.cpp— transpile.tson load, and probe for.tsduring resolution. Both are behind#if JSB_WITH_TYPESCRIPT_TRANSPILER, so with the flag off the resolver behaves exactly as today (no.tsprobe, no transpile path).weaver/jsb_script.cpp— with the flag on, attach a.tsscript by loading the.tssource directly (transpiled in-process); with the flag off it keeps loading thetsc-emitted.jsviaconvert_typescript_path, as before this change.What it costs (please weigh this)
With the flag on, building the engine needs a Rust toolchain (
cargoonPATH), and the first build downloads and compiles the SWC dependency tree (pinned inCargo.lock). With the flag off — the default — there is no new prerequisite: no Rust, no cargo build, and the engine builds exactly as it does today.Robustness
The Rust FFI is panic-safe: a panic inside the transpiler (for example SWC choking on malformed input) is caught at the C boundary and returned as an error result, never unwinding into the engine.
How to verify
use_typescript_transpiler=yes: build on Linux, Windows, and macOS — the static-link fix (allowing duplicaterust_eh_personalitysymbols against Godot's prebuilt static libs) specifically needs cross-platform confirmation. Then load a.tsmodule and confirm it runs without a separatetscstep.A changeset is included.