Function run_emcc

ci/wasm_tools.py:278–319

Run emcc with the given args, trying in-process first, falling back to subprocess. Args: args: Command-line arguments (WITHOUT the 'emcc' prefix — just flags and files). cwd: Working directory for the invocation. Returns: Process return code (0 = success).

(args: list[str], cwd: Optional[str] = None)

def run_emcc(args: list[str], cwd: Optional[str] = None) -> int:
    """Run emcc with the given args, trying in-process first, falling back to subprocess.

    Args:
        args: Command-line arguments (WITHOUT the 'emcc' prefix — just flags and files).
        cwd: Working directory for the invocation.

    Returns:
        Process return code (0 = success).
    """
    # Verify the EMCC_WASM_LD patch is applied to the bundled emscripten
    # install. This was previously in _render_wasm_cross_file (called on every
    # warm build) — moved here in 2026-05 so the cost is paid only when emcc.py
    # is actually about to be imported in-process. On clang-tool-chain >=1.5.5
    # with a settled install, this is a ~1 ms marker-file stat; on older or
    # freshly-extracted installs it does the full check.
    #
    # Lazy import to avoid the wasm_build <-> wasm_tools circular dep.
    from ci.wasm_build import _ensure_emscripten_wasm_ld_patch

    _ensure_emscripten_wasm_ld_patch()

    mod = _load_emcc_module()
    if mod is not None:
        # In-process invocation — save/restore global state
        old_argv = sys.argv
        old_cwd = os.getcwd()
        try:
            sys.argv = ["emcc"] + args
            if cwd:
                os.chdir(cwd)
            return mod.main(sys.argv)  # type: ignore[union-attr]
        except SystemExit as e:
            return e.code if isinstance(e.code, int) else 1
        finally:
            sys.argv = old_argv
            os.chdir(old_cwd)

    # Fallback: subprocess
    emcc = get_emcc()
    result = subprocess.run([emcc] + args, cwd=cwd)
    return result.returncode