Windows: Fix `TooManyParentDirs` handling for paths that shouldn't be cwd-relative

Previously, a relative path like `..` would:
- Attempt to be normalized (i.e. remove . and .. without any path resolution), but would error with TooManyParentDirs
- This would make wToPrefixedFileW run it through `RtlGetFullPathName_U` to do the necessary path resolution, but `RtlGetFullPathName_U` always resolves relative paths relative to the CWD

Instead, when TooManyParentDirs occurs, we now look up the path of the passed in `dir` (if it's non-null) and append the relative path to it before giving it to `RtlGetFullPathName_U`. If `dir` is null, then we just give it RtlGetFullPathName_U directly and let it resolve it relative to the CWD.

Closes #16779

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/std/child_process.zig b/lib/std/child_process.zig
index efa76b4e72..6ddb92f55d 100644
--- a/lib/std/child_process.zig
+++ b/lib/std/child_process.zig
@@ -961,7 +961,7 @@ fn windowsCreateProcessPathExt(
         try dir_buf.append(allocator, 0);
         defer dir_buf.shrinkRetainingCapacity(dir_path_len);
         const dir_path_z = dir_buf.items[0 .. dir_buf.items.len - 1 :0];
-        const prefixed_path = try windows.wToPrefixedFileW(dir_path_z);
+        const prefixed_path = try windows.wToPrefixedFileW(null, dir_path_z);
         break :dir fs.cwd().openDirW(prefixed_path.span().ptr, .{}, true) catch return error.FileNotFound;
     };
     defer dir.close();