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Suggested reviewers: Merge Risk: 🔵 Low · up to The change is mergeable with a bounded follow-up to add the required issue URL to the regression test comment. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Inline comments:
In `@src/bundler/linker_context/postProcessJSChunk.rs`:
- Around line 39-63: Propagate Flags::HAS_IMPORT_META when constructing
synthetic SQLite ASTs that contain E::ImportMeta before lazy AST conversion, so
chunk_uses_import_meta detects them and emits the CJS wrapper parameter. Add a
regression test covering a SQLite import with --target=bun and --format=cjs.
Apply the same fix in `@test/bundler/bundler_bun.test.ts` around lines 231 - 252.
In `@src/js_printer/lib.rs`:
- Around line 2977-2997: Verify the import_meta_ref handling in the printer
branch, including the non-bundled --format=cjs runtime-transpiler path and the
adjacent `@bun-cjs` wrapper branch. Confirm whether the new third branch resolves
the documented failure; if so, remove or correct the stale TODO and
debug_assert, otherwise preserve the assertion and address the unresolved edge
case with a follow-up issue.
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src/ast/e.rssrc/bundler/ParseTask.rssrc/bundler/linker_context/postProcessJSChunk.rssrc/bundler/transpiler.rssrc/js_parser/fold.rssrc/js_parser/p.rssrc/js_parser/parse/parse_entry.rssrc/js_printer/lib.rssrc/js_printer/renamer.rstest/bundler/bundler_bun.test.ts
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Inline comments:
In `@test/bundler/bundler_bun.test.ts`:
- Around line 231-232: Add the relevant issue URL to the regression-test comment
near the sqlite loader explanation, preserving the existing comment text and
using the repository’s standard issue-link format.
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I re-reviewed after 767beef and 8b4d92c — the sqlite-loader flag mismatch I flagged earlier is fixed (ast.has_import_meta = true on the lazy-export AST, plus the ImportMetaFormatCjsEmbeddedSqlite test), and this run found no further bugs. Given this coordinates an invariant across the parser, printer, renamer, and linker for @bun-cjs output, a maintainer look would still be worthwhile.
What was reviewed:
- The printer's
CJS_WRAPPER_ARGbranch vs.chunk_uses_import_meta— both key onc.options.target(LinkerContext.rs:2239 / postProcessJSChunk.rs:41), so the argument and its uses agree; the hashbang-forces-bun-entry case falls through to the old inlining as described. compute_initial_reserved_namesreserving$Bun_import_metaonly forFormat::Cjs, and the minify test exercising the rename of a colliding user variable.- The
inline_import_meta_pathsgate in fold.rs vs. its assignment in ParseTask.rs — Bake and non-bun cjs keep the source-path inlining, everything else defers to the runtime object. - The runtime-transpiler
import_meta_refbranch is unchanged (transpiler.rs setsbundling: false, so the new printer arm is unreachable there).
Extended reasoning...
Overview
This PR stops bun build --target=bun --format=cjs (and by extension --bytecode / --compile --bytecode) from baking the build machine's absolute source paths into import.meta.path/.dir/.file/.url. Instead, the @bun-cjs wrapper now declares a sixth $Bun_import_meta parameter (which JSCommonJSModule.cpp already passes at runtime), the printer emits E::ImportMeta as that identifier for bun-target bundled cjs output, the renamer reserves the name, and the parser's path-inlining fold is gated behind a new inline_import_meta_paths option that ParseTask sets only for Bake and non-bun cjs targets. Ten files touched across ast, js_parser, js_printer, and bundler, plus five new itBundled tests.
Security risks
None identified. The change removes build-machine paths from shipped binaries (a minor info-leak improvement). No untrusted-input parsing, no auth/crypto/permissions surface.
Level of scrutiny
Medium-high. The bundler's cjs wrapper is on the --compile --bytecode production path, and the correctness argument depends on a cross-file invariant: the printer emits $Bun_import_meta exactly when the linker declares it on the wrapper. I traced both sides to c.options.target (printer options at LinkerContext.rs:2239 and chunk_uses_import_meta's guard) and to the per-file HAS_IMPORT_META flag (now also set for the sqlite loader's synthetic AST). The test matrix covers plain cjs, +minify, +bytecode, the sqlite-only-import.meta chunk, the no-import.meta chunk (five-arg wrapper), and --compile --bytecode end-to-end.
Other factors
My prior inline finding (the sqlite loader's synthetic import.meta not carrying HAS_IMPORT_META) was addressed in 767beef with both the flag assignment and a dedicated test that asserts the six-arg wrapper header and runs the output. All comment-cop and CodeRabbit threads are resolved. The PR description is unusually thorough about interactions with four related open PRs. Still, this is bundler output-shape work with a coordinated invariant across four crates — the kind of change where a maintainer familiar with the @bun-cjs wrapper and per-file vs. build target semantics should confirm the design before merge.
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The rework addresses my earlier concern — the wrapper header is now driven by PrintResultSuccess::uses_import_meta_arg (set exactly when the printer emits $Bun_import_meta), so the sqlite loader's synthesized E::ImportMeta and any other non-lexer path are covered by construction. I reviewed the reworked design and didn't find further issues.
Given the scope — new option threaded through parser → linker → printer → post-process, a per-chunk decision that changes --compile --bytecode output semantics, and interaction with four related open PRs — a human look is still worthwhile.
What was reviewed:
- Printer/header agreement:
inside_bun_cjs_wrappergates emission,chunk_uses_import_meta_argreads the printer's own flag from populated compile results — no path can emit the identifier without the header declaring it. - HTML-import browser chunks:
chunk_has_bun_cjs_wrapperkeys on the chunk entry's target, so browser chunks getinside_bun_cjs_wrapper=falseand keepimport.meta(covered by the new test). - Renamer reservation applies to both
MinifyRenamerandNumberRenamer(added before the minify branch). - Entry-point tail and cross-chunk prefix/suffix use
inside_bun_cjs_wrapper: false(default) and never containE::ImportMeta, so they can't desync the header.
Extended reasoning...
Overview
This PR fixes import.meta.* in bun build --format=cjs / --bytecode / --compile output for the bun target: instead of inlining build-machine source paths (leaking the build tree into shipped binaries and breaking import.meta.dir-relative asset lookups), the @bun-cjs wrapper now declares a sixth $Bun_import_meta parameter that the runtime already passes, and the printer emits that identifier for every import.meta inside such a chunk. It touches 14 files across the parser (fold.rs, parse_entry.rs, p.rs), bundler linker (LinkerContext.rs, generateCodeForFileInChunkJS.rs, generateCompileResultForJSChunk.rs, postProcessJSChunk.rs, renameSymbolsInChunk.rs, ParseTask.rs), printer (lib.rs), AST (e.rs), and adds 7 tests to bundler_bun.test.ts.
Prior review and rework
I flagged one bug on the first revision: the wrapper header was keyed on the per-file HAS_IMPORT_META lexer flag while the printer emitted $Bun_import_meta on a broader predicate, so the sqlite loader's synthesized import.meta.require(...) would print the identifier in a chunk whose header did not declare it → runtime ReferenceError. The author reworked the design (commits ecc7e54 and later): the decision is now centralized in LinkerContext::chunk_has_bun_cjs_wrapper, threaded to the printer as inside_bun_cjs_wrapper, and the printer reports uses_import_meta_arg on its result. post_process_js_chunk reads that flag across the chunk's already-populated compile results to decide whether to emit the sixth parameter. Emission and declaration are now the same predicate by construction, which resolves the sqlite case and the HTML-import browser-chunk case the description mentions. The bun/ImportMetaFormatCjsEmbeddedSqlite and bun/ImportMetaFormatCjsHtmlImport tests cover both.
Security risks
The change removes a path-leak (build-machine absolute paths in shipped binaries). No new untrusted-input parsing. The reserved name $Bun_import_meta is added to the chunk renamer's reserved set, so a user-declared $Bun_import_meta is renamed rather than shadowing the wrapper argument (tested in importMetaFiles, both top-level and nested-scope).
Level of scrutiny
High. This is core bundler linking/printing, affects the documented production command bun build --compile --bytecode, changes user-visible import.meta semantics for cjs output, and the PR description explicitly maps interactions with four other open PRs (#38173, #33859, #38200, #29066). The design has already been reworked once after review found a correctness issue. A maintainer should confirm the per-chunk-entry-target predicate for chunk_has_bun_cjs_wrapper is the intended long-term home (the description notes #33859 will narrow it further) and weigh the noted behavior change for non-compile --target=bun --format=cjs bundles (import.meta.dir now reports the output directory at runtime, matching esm).
Other factors
Test coverage is thorough — the 7 new itBundled cases cover cjs / cjs+minify / cjs+bytecode, the unused-argument case, embedded sqlite, HTML import (mixed-target chunks), and compile+bytecode with a /$bunfs path assertion and bytecode cache-hit check. The evidence block shows 6/7 fail on main and all 17 pass on the branch (debug+ASAN and release). All bot comment threads (comment-cop, coderabbit, my prior finding) are resolved.
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Closed #28692 in favor of this PR. On a build of this branch, the |
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This also fixes #40903, the worker case: in a I verified this branch merged with current main (1ab272b, which has #40619): the repro from #40903 now prints |
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Verified a case from a fuzz matrix on top of current main ( On main this prints |
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Any update? What is the expected timeline to get this merged/released? |
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Note GitHub couldn't provide a complete incremental comparison for this pull request, so CodeRabbit is performing a full review instead. This review may take a little longer. |
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Rebased onto current main ( Verified on main before the rebase that this PR is still needed. With a debug build of
Also run on the rebased build: |
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3 participants
Problem
bun build --compile --bytecodebakes the build machine's source paths intoimport.meta.path,.dir,.fileand.url. Without--bytecodethe same build reports/$bunfs/root/<name>.--format=cjsalone does the same.--assetlookups underimport.meta.dirbreak, and every shipped binary contains the build tree.src/js_parser/fold.rs:513inlines those properties as the source paths for all cjs output (fix(bundler):import.meta.urland esm wrapper fixes #23803, for theimport.meta is only valid inside modulesSyntaxError of Usingimport.meta.dirwhen compiling with--bytecodeflag throws error #14954). Every other use ofimport.metastill throws that SyntaxError in cjs output, which isimport.meta.envcauses a crypticTypeErrorinbun build --compile#21097.Fix
import.metaas a sixth argument when the wrapper declares one (JSCommonJSModule.cpp:228).LinkerContext::chunk_has_bun_cjs_wrapperdecides once per chunk whether the chunk gets the@bun-cjswrapper. The header and footer, the chunk renamer (which reserves the name$Bun_import_metathere) and a printer option for every file in the chunk use that answer.import.metaas$Bun_import_metaand reports that on its result. The header declares the argument when any part range reported it. Chunks without the wrapper, such as the browser chunk of an HTML import, printimport.metaas before.inline_import_meta_paths, set inParseTask).ZigGlobalObject.cpp:3923), so cjs output gets the ESM values for every property. Output that does not useimport.metais unchanged.test/bundler/bundler_bun.test.ts, 7 new tests, 6 fail on the released build. Other suites are listed in the notes.Background
(function(exports, require, module, __filename, __dirname) {...})script that the runtime calls, and that--bytecodecompiles.import.metais a syntax error in a script. A bun build with an HTML import also emits browser chunks, which are plain module scripts without the wrapper.$Bun_import_metais the name the runtime transpiler already uses for this argument when it wraps a CommonJS file that usesimport.meta. Both sites readE::ImportMeta::CJS_WRAPPER_ARG.exportsandmoduleare reserved in cjs output the same way, which is what lets the printer emitrequire.main == moduleby name.PrintResultSuccessis what the printer returns per part range. bundler: build the ESM bytecode module record from what the printer emits #37677 derives the ESM bytecode module record from what the printer emitted instead of from the AST. The newuses_import_meta_argflag on it follows that pattern.Fixes #21097
Notes
Repro on main, and the binary built from this branch:
The sixth argument hook dates from #3104 (2023), so it predates
@bun-cjsoutput (#14232). Bundles built this way load on every Bun that can load@bun-cjsoutput. #19250's closing note lists these inlinedimport.metavalues as the remaining build paths in a--bytecodebinary.Output of a plain
bun build --target=bun --format=cjsfor a file that usesimport.meta, plus a.cjsdependency that uses it too:A user variable with the reserved name is renamed, in nested scopes too.
--minifyoutput keeps the argument because the header is printed by the linker. Non-compile--target=bun --format=cjsbundles change as well:import.meta.diris now the output directory at run time, which is what esm output of the same build already reported. cjs output for node and browser, esm output, iife output and Bake are unchanged. The embedded sqlite module, which the loader builds asimport.meta.require(...)without the parser, now works in cjs output too, because the argument is declared from what the printer emitted, not from a parser flag.Revision history. The first revision keyed the printer on the build's target and declared the argument from the per-file
HAS_IMPORT_METAflag. Review of that revision found two things. The sqlite module has no such flag, so it was patched with one (commit 767beef, now removed). And a bun build with an HTML import prints browser chunks with the same printer options, soimport.meta.envin a client file became a bare$Bun_import_metareference in a chunk that has no wrapper (main shipsimport.metathere). Reproduced with this branch's debug build before the rework. The current revision keys everything onchunk_has_bun_cjs_wrapperand is covered bybun/ImportMetaFormatCjsHtmlImport, which checks that the browser chunk still containsimport.metaand that only the server chunk is wrapped. A--target=node --format=cjsbuild whose entry has a#!/usr/bin/env bunhashbang gets the wrapper today, because the entry's own target is bun. The entry file now uses the argument (its target is bun, so nothing is inlined) and the other files keep the inlined paths. Checked: such a bundle runs, andimport.meta.envin it used to be a SyntaxError.Related open PRs, and how this composes with them:
require(...)in cjs output. No shared lines any more. Its tests pinrequire(, the test here only runs the bundle, so both pass in either order.chunk_has_bun_cjs_wrapper, so its narrowing goes there, and the header block has a small textual conflict either way.import.metato an empty per-file object for cjs and iife output of other targets. Whichever lands second excludes the files this PR leaves alone (cjs output for bun), where the wrapper supplies the real object. Itsinline_import_metagate andinline_import_meta_pathshere are the same predicate.__dirname/__filenameuse the virtual path in--compileoutput (the CJS sibling in the fuzz ledger). It also rewritesimport.meta.dir/.dirname/.path/.filenameto those identifiers for--compilecjs output and leaves.urland.fileinlined. With this PR that fold.rs hunk is not needed. Its__dirnamechange and Windows separator fix are independent.Found while testing and handed off separately: two bundled modules that both use
__dirnamecollide (the last declaration wins), andnew Worker(new URL("./w.ts", import.meta.url))from the executables docs fails in every standalone executable withModuleNotFound /$bunfs/root/w.ts(the.tsto.jsremap only applies to relative specifiers). A--bytecodebuild of that docs example only appeared to work before because it loaded the worker from the source tree on the build machine.Test placement:
compile/HelloWorldWithProcessVersionsBuninbundler_compile.test.tsfails on every debug build independent of this change, so the new compile case lives inbundler_bun.test.ts, which is green on a debug build. The compile case also readsimport.meta.env, which is the #21097 program. Threebake/dev/productiontests timed out locally at the 5 s default and pass with a longer timeout. They do not involveimport.meta.Suites run with the debug build after the rework:
bundler_bun(17 tests),bundler_banner,bundler_cjs,html-import-manifest,bundler_html_server,bundler_edgecase,bun-build-api,esbuild/default -t "ImportMeta|import.meta",bundler_compile -t "Bytecode|ImportMeta|pathToFileURLWorks|sqlite|html",bake/dev/import-meta-inline,js/bun/resolve/import-meta.cargo clippyandcargo fmtare clean for the four touched crates.[human-review] gate passed · iteration 1 · 14 files touched
fails on main (without fix)
passes on PR (with fix)
diff hotspot
gate history · 3 passed · 0 rejected · iteration 1
evidence per changed file
root cause · written by the author bot
When the bundler lowers a Bun target to CommonJS (which
--bytecodeimplies), the parser inlinesimport.meta.url,import.meta.path,import.meta.dir, andimport.meta.fileas string constants taken from the build machine's source path, so the standalone executable reports the build directory instead of the virtual/$bunfs/root/<name>location that the non-CJS compile uses. The fix makesinline_import_meta_pathsan explicit opt-in that stays off for Bun CommonJS compile output and instead threads a wrapper argument through the linker and printer, so the Bun CJS module wrapper rece…