bazelbuild/bazel · error

prefix msg "\n"

Error message

prefix msg "\n"

What it means

On Windows, singlejar's diag.h implements its diagnostics (diag_err, diag_errx, diag_warn, diag_warnx) as macros that fprintf 'prefix + msg + newline' to stderr; the _diag_msgx variants then call ::ExitProcess(exit_value), terminating the zip creation tool immediately. The message template here is the shared body that stamps 'ERROR: ' or 'WARNING: ' in front of every singlejar diagnostic on Windows.

Source

Thrown at src/tools/singlejar/diag.h:41

    defined(__OpenBSD__)

#include <err.h>
#define diag_err(...) err(__VA_ARGS__)
#define diag_errx(...) errx(__VA_ARGS__)
#define diag_warn(...) warn(__VA_ARGS__)
#define diag_warnx(...) warnx(__VA_ARGS__)

#elif defined(_WIN32)

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <stdio.h>
#include <string.h>
#include <windows.h>
#define _diag_msg(prefix, msg, ...)                  \
  {                                                  \
    fprintf(stderr, prefix msg "\n", ##__VA_ARGS__); \
  }
#define _diag_msgx(exit_value, prefix, msg, ...) \
  {                                              \
    _diag_msg(prefix, msg, ##__VA_ARGS__);       \
    ::ExitProcess(exit_value);                   \
  }
#define diag_err(exit_value, fmt, ...) \
  _diag_msgx(exit_value, "ERROR: ", fmt, ##__VA_ARGS__)
#define diag_errx(exit_value, fmt, ...) \
  _diag_msgx(exit_value, "ERROR: ", fmt, ##__VA_ARGS__)
#define diag_warn(fmt, ...) _diag_msg("WARNING: ", fmt, ##__VA_ARGS__)
#define diag_warnx(fmt, ...) _diag_msg("WARNING: ", fmt, ##__VA_ARGS__)

#else
#error Unknown platform
#endif

#endif  // BAZEL_SRC_TOOLS_SINGLEJAR_DIAG_H_

View on GitHub (pinned to e6e199d060)

Solutions

1. Check whether the output jar named in the preceding message is locked/read-only; close editors and rerun.
2. Rerun the failing action with --subcommands to capture the exact singlejar invocation and run it manually to see the full diagnostic.
3. Shorten output paths (enable Windows long-path support or move the workspace closer to the drive root).
4. Verify free disk space on the output volume.
5. If entries are reported duplicated, check the srcs of the java_singlejar/proto rule for the same file listed twice.

// before singlejar runs, clear Windows file-lock obstacles on the output
// (pseudo) if exists(output) { clear_readonly(output); fail if locked }
std::error_code ec;
auto st = std::filesystem::status(out_path, ec);
if (!ec && exists(st)) {
  std::filesystem::permissions(out_path, std::filesystem::perms::owner_write, std::filesystem::perm_options::add, ec);
  if (ec) return error("output not writable: " + out_path.string());
}

When it happens

Trigger: Calling singlejar (via Bazel's java_singlejar or proto bundling actions) on Windows when zip entry insertion fails, output file cannot be written, entry names collide, or the output zip already exists read-only; each failure path formats its message through _diag_msg before ExitProcess for the err variants.

Common situations: Output .jar marked read-only or locked by another process (VS, antivirus); path length beyond MAX_PATH; duplicate entry names when merging jars; disk full on the output drive during a Windows build.

Related errors

• Not a log level: " + input
• __FILE__ ":" S__LINE__ ": \"" __VA_ARGS__
• Could not seek to end of file (%s)
• Waiting for previous Bazel server's log file to close (waite
• Cannot write PID file %s

AI-assisted analysis of bazelbuild/bazel@e6e199d060 (2026-08-14). Data as JSON: /api/errors/4ea3cc8917457db0. Report an issue: GitHub.