bun-src/scripts/build/depVersionsHeader.ts

/**
 * Generates bun_dependency_versions.h — a header with dep version strings
 * for `process.versions` and similar runtime introspection.
 *
 * Version values are DERIVED from `allDeps` — each dep's `source(cfg)`
 * provides its commit/identity. Bumping a dep in `deps/<name>.ts`
 * automatically updates this header. Single source of truth.
 *
 * Written at configure time. writeIfChanged semantics so changing an
 * unrelated dep doesn't recompile everything via this header's mtime.
 *
 * Source: cmake/tools/GenerateDependencyVersions.cmake
 */

import { mkdirSync } from "node:fs";
import { resolve } from "node:path";
import type { Config } from "./config.ts";
import { allDeps } from "./deps/index.ts";
import { writeIfChanged } from "./fs.ts";
import type { Source } from "./source.ts";

/**
 * Pull a version identifier from a Source. The shape depends on the kind:
 * github-archive → commit hash, prebuilt → identity string. Local/in-tree
 * don't have a pinned identifier.
 */
function sourceIdentifier(source: Source): string | undefined {
  switch (source.kind) {
    case "github-archive":
      return source.commit;
    case "prebuilt":
      return source.identity;
    case "local":
    case "in-tree":
      // User-managed / in-tree — no pinned identifier independent of the
      // bun commit. Callers that need a value use cfg.revision.
      return undefined;
  }
}

/**
 * (macro_name, value) pairs. Values that can't be determined are omitted
 * from output (CMake behavior — consumers check #ifdef).
 */
function computeVersions(cfg: Config): [string, string][] {
  const versions: [string, string][] = [];

  // ─── Deps: derived from allDeps source definitions ───
  // Single source of truth — bumping deps/<name>.ts updates this.
  for (const dep of allDeps) {
    if (dep.versionMacro === undefined) continue;
    const source = dep.source(cfg);
    const id = sourceIdentifier(source);
    // WebKit special case: prebuilt.identity carries the artifact suffix, but
    // process.versions wants the version. Strip the autobuild- prefix so tags
    // report the clean sha and previews report preview-pr-<N>-<sha8>.
    if (dep.name === "WebKit") {
      const v = cfg.webkitVersion;
      versions.push([dep.versionMacro, v.startsWith("autobuild-") ? v.slice("autobuild-".length) : v]);
    } else if (id !== undefined) {
      versions.push([dep.versionMacro, id]);
    }
    // local/in-tree with no identifier: omit (consumer does #ifdef)
  }

  // ─── Non-dep versions ───
  // UWS/USOCKETS are vendored at packages/bun-usockets — the bun commit
  // IS their version.
  versions.push(["UWS", cfg.revision]);
  versions.push(["USOCKETS", cfg.revision]);
  // The runtime was ported from Zig; `process.versions.zig` records the
  // upstream Zig commit it derives from. The build no longer uses a Zig
  // toolchain, so this is a fixed historical reference rather than a live pin.
  versions.push(["ZIG", "04e7f6ac1e009525bc00934f20199c68f04e0a24"]);

  // NOTE: cmake's GenerateDependencyVersions.cmake also extracted semantic
  // versions (LIBDEFLATE_VERSION="1.19", ZLIB_VERSION="1.2.8") from vendor
  // headers. Those macros were never consumed — BunProcess.cpp only reads
  // the _HASH (commit) macros for process.versions. The extraction is also
  // a chicken-and-egg: it runs at configure time but vendor headers exist
  // only after fetch, so on a clean checkout the header content flips on
  // the second configure → spurious rebuild. Dropping the dead code.

  return versions;
}

/**
 * Generate bun_dependency_versions.h at buildDir/. Returns the absolute path.
 */
export function generateDepVersionsHeader(cfg: Config): string {
  const outPath = resolve(cfg.buildDir, "bun_dependency_versions.h");
  const versions = computeVersions(cfg).filter(([, v]) => v !== "" && v !== "unknown");

  const lines: string[] = [
    "// Auto-generated by scripts/build/depVersionsHeader.ts. Do not edit.",
    "// Version values derived from scripts/build/deps/*.ts source definitions.",
    "#ifndef BUN_DEPENDENCY_VERSIONS_H",
    "#define BUN_DEPENDENCY_VERSIONS_H",
    "",
    "#ifdef __cplusplus",
    'extern "C" {',
    "#endif",
    "",
    "// Dependency versions",
    ...versions.map(([name, val]) => `#define BUN_DEP_${name} "${val}"`),
    "",
    "// C string constants for easy access",
    ...versions.map(([name, val]) => `static const char* const BUN_VERSION_${name} = "${val}";`),
    "",
    "#ifdef __cplusplus",
    "}",
    "#endif",
    "",
    "#endif // BUN_DEPENDENCY_VERSIONS_H",
    "",
  ];

  mkdirSync(cfg.buildDir, { recursive: true });
  writeIfChanged(outPath, lines.join("\n"));
  return outPath;
}