Fix Windows metadata validation for cross-compilation targets

[robobun]

Summary

• Fixed validation for Windows metadata flags when cross-compiling to non-Windows targets
• Provides clear error messages when Windows metadata is used with incompatible targets

Problem

When using Windows metadata flags (--windows-title, --windows-publisher, etc.) with a non-Windows compile target (e.g., --target bun-linux-x64), the error message was unclear:

error: expect(received).toContain(expected)
Expected to contain: "target platform"
Received: "failed to set windows metadata: failedtoloadexecutable\n"

Solution

Added proper validation that checks:

1. Whether Windows metadata flags are being used with a non-Windows compile target
2. Whether the host platform supports setting Windows metadata (must be Windows)

Now provides clear error messages:

• When targeting non-Windows: "Windows metadata flags... can only be used when targeting Windows. Current target platform: linux"
• When cross-compiling to Windows from non-Windows: "Windows metadata flags can only be used when compiling on Windows"

Test Status

✅ The failing test "windows flags with non-Windows target should error" now passes
✅ Verified both error scenarios work correctly

🤖 Generated with Claude Code

[robobun]

^{Updated 5:12 PM PT - Sep 15th, 2025}

❌ Your commit 071848fd has 2 failures in Build #26110 (All Failures):

• test/integration/mysql2/mysql2.test.ts - timeout on 🍎 13 aarch64
• test/js/node/worker_threads/worker_threads.test.ts - pid 26810 segmentation fault on 🐧 24.04 x64-baseline

---

🧪   To try this PR locally:

bunx bun-pr 22703

That installs a local version of the PR into your bun-22703 executable, so you can run:

bun-22703 --bun

[coderabbitai]

Walkthrough

Removed per-flag host OS checks for Windows metadata flags and added BuildCommand-scoped validation. During compile, target OS is derived (explicit compile target or current environment). If Windows metadata is used with non-Windows target, or non-Windows host targets Windows, the command crashes. No public API changes.

Changes

Cohort / File(s)	Summary
CLI argument validation src/cli/Arguments.zig	Removed per-flag Windows-only checks. Added BuildCommand-scoped validation: resolves target OS (from compile_target.os or environment), and errors if Windows metadata is used for non-Windows targets or when targeting Windows from a non-Windows host during --compile. No exported/public signatures changed.

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title "Fix Windows metadata validation for cross-compilation targets" succinctly and accurately summarizes the primary change—correcting validation and error messages for Windows metadata flags when targeting or building for non-Windows platforms. It directly matches the PR objectives and raw summary about validating Windows metadata usage during cross-compilation and hosts. The title is concise, specific, and appropriate for a teammate scanning commit history.
Description Check	✅ Passed	The description provides a clear Summary, Problem, Solution, and Test Status that explain what the PR does and reports verification that the failing test now passes, so the core information required by the template is present. It does not strictly use the repository's exact template headings ("What does this PR do?" and "How did you verify your code works?") and the verification details are brief rather than step-by-step. Because the essential details and test outcomes are included, the check passes but the description should be aligned to the template for clarity and reproducibility.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch claude/fix-windows-metadata-validation

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (3)

src/cli/Arguments.zig (3)

970-996: Drop redundant comptime guard.

This block sits inside an enclosing BuildCommand branch already; the inner if (comptime cmd == .BuildCommand) is noise.

Apply:

-        if (comptime cmd == .BuildCommand) {
-            const has_windows_metadata = ctx.bundler_options.windows.title != null or
+        // Validate Windows metadata usage (BuildCommand context)
+        const has_windows_metadata = ctx.bundler_options.windows.title != null or
             ctx.bundler_options.windows.publisher != null or
             ctx.bundler_options.windows.version != null or
             ctx.bundler_options.windows.description != null or
             ctx.bundler_options.windows.copyright != null;
@@
-        }

---

977-983: Optional debug trace to aid support.

Add a scoped debug log showing derived target/host only when crash tracing is enabled. Aligns with repo logging guidance.

             if (has_windows_metadata and ctx.bundler_options.compile) {
                 // Check the target platform
                 const target_os = if (!ctx.bundler_options.compile_target.isDefault())
                     ctx.bundler_options.compile_target.os
                 else
                     Environment.os;
+                if (Environment.show_crash_trace) {
+                    const log = Output.scoped(.cli, false);
+                    log("validate windows metadata: target_os={s}, host_is_windows={}", .{ @tagName(target_os), Environment.isWindows });
+                }

---

984-994: Tighten wording of errors (nit).

Avoid “etc.” and say “OS” to be precise; add a brief remediation hint for cross-compiles.

-                if (target_os != .windows) {
-                    Output.errGeneric("Windows metadata flags (--windows-title, --windows-publisher, etc.) can only be used when targeting Windows. Current target platform: {s}", .{@tagName(target_os)});
+                if (target_os != .windows) {
+                    Output.errGeneric("Windows metadata flags can only be used when targeting Windows. Current target OS: {s}", .{@tagName(target_os)});
                     Global.crash();
                 }
@@
-                if (!Environment.isWindows and target_os == .windows) {
-                    Output.errGeneric("Windows metadata flags can only be used when compiling on Windows", .{});
+                if (!Environment.isWindows and target_os == .windows) {
+                    Output.errGeneric("Windows metadata flags can only be used when compiling on Windows. Run this build on a Windows host.", .{});
                     Global.crash();
                 }

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📥 Commits

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📒 Files selected for processing (1)

• src/cli/Arguments.zig (1 hunks)

🧰 Additional context used

📓 Path-based instructions (2)

src/**/*.zig

📄 CodeRabbit inference engine (.cursor/rules/building-bun.mdc)

Implement debug logs in Zig using const log = bun.Output.scoped(.${SCOPE}, false); and invoking log("...", .{})

Files:

• src/cli/Arguments.zig

**/*.zig

📄 CodeRabbit inference engine (.cursor/rules/javascriptcore-class.mdc)

**/*.zig: Declare the extern C symbol in Zig and export a Zig-friendly alias for use
Wrap the Bun____toJS extern in a Zig method that takes a JSGlobalObject and returns JSC.JSValue

**/*.zig: Format Zig files with zig-format (bun run zig-format)
In Zig, manage memory carefully with allocators and use defer for cleanup

Files:

• src/cli/Arguments.zig

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🔇 Additional comments (1)

src/cli/Arguments.zig (1)

969-996: Validation logic LGTM; matches PR intent.

Correctly derives target OS, gates on --compile, and emits clear errors for non-Windows targets and non-Windows hosts. Nice placement after options are parsed.

Please confirm the two user-visible error strings are exactly what your tests assert against (including punctuation/casing).