fix: resolve ENOENT error when using --filter with workspace packages having mixed case names

Fixed an issue where workspace filtering would fail with ENOENT when package
directories had mixed case names (e.g., camelCase, kebab-case). The problem
was in the glob walker's directory iterator which was using lowercase hash map
keys instead of the original case-preserved directory names when constructing
file paths.

The fix changes the DirEntryAccessor to use `nextval.value_ptr.*.base()`
(original case) instead of `nextval.key_ptr.*` (lowercase key) when iterating
over directory entries. This ensures that file system operations use the
correct case-sensitive directory names.

Fixes: https://github.com/oven-sh/bun/issues/21670

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/glob/GlobWalker.zig

@@ -211,7 +211,7 @@ pub const DirEntryAccessor = struct {
         pub inline fn next(self: *DirIter) Maybe(?IterResult) {
             if (self.value) |*value| {
                 const nextval = value.next() orelse return .{ .result = null };
-                const name = nextval.key_ptr.*;
+                const name = nextval.value_ptr.*.base();
                 const kind = nextval.value_ptr.*.kind(&FS.instance.fs, true);
                 const fskind = switch (kind) {
                     .file => std.fs.File.Kind.file,

test/cli/run/filter-workspace-case-sensitivity.test.ts

@@ -0,0 +1,132 @@
+import { test, expect } from "bun:test";
+import { bunEnv, bunExe, tempDirWithFiles } from "harness";
+
+test("--filter should work with packages containing mixed case names", async () => {
+  const dir = tempDirWithFiles("filter-workspace-case-sensitivity", {
+    "package.json": JSON.stringify({
+      name: "test-workspace",
+      workspaces: ["packages/*"],
+      private: true,
+    }),
+    "packages/camelCase/package.json": JSON.stringify({
+      name: "camelCase",
+      version: "1.0.0",
+      scripts: {
+        test: "echo 'camelCase test passed'",
+      },
+    }),
+    "packages/kebab-case/package.json": JSON.stringify({
+      name: "kebab-case",
+      version: "1.0.0",
+      scripts: {
+        test: "echo 'kebab-case test passed'",
+      },
+    }),
+    "packages/UPPERCASE/package.json": JSON.stringify({
+      name: "UPPERCASE",
+      version: "1.0.0",
+      scripts: {
+        test: "echo 'UPPERCASE test passed'",
+      },
+    }),
+  });
+
+  // Install workspace dependencies
+  const proc = Bun.spawn({
+    cmd: [bunExe(), "install"],
+    env: bunEnv,
+    cwd: dir,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  await proc.exited;
+
+  // Test filtering specific packages by name
+  for (const packageName of ["camelCase", "kebab-case", "UPPERCASE"]) {
+    const proc = Bun.spawn({
+      cmd: [bunExe(), "run", "--filter", packageName, "test"],
+      env: bunEnv,
+      cwd: dir,
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+
+    const [stdout, stderr, exitCode] = await Promise.all([
+      proc.stdout.text(),
+      proc.stderr.text(),
+      proc.exited,
+    ]);
+
+    expect(exitCode).toBe(0);
+    expect(stdout).toContain(`${packageName} test passed`);
+    expect(stderr).not.toContain("error: ENOENT");
+  }
+
+  // Test filtering all packages
+  const proc2 = Bun.spawn({
+    cmd: [bunExe(), "run", "--filter", "*", "test"],
+    env: bunEnv,
+    cwd: dir,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout2, stderr2, exitCode2] = await Promise.all([
+    proc2.stdout.text(),
+    proc2.stderr.text(),
+    proc2.exited,
+  ]);
+
+  expect(exitCode2).toBe(0);
+  expect(stdout2).toContain("camelCase test passed");
+  expect(stdout2).toContain("kebab-case test passed");
+  expect(stdout2).toContain("UPPERCASE test passed");
+  expect(stderr2).not.toContain("error: ENOENT");
+});
+
+test("--filter should work with directory names that differ in case from package names", async () => {
+  const dir = tempDirWithFiles("filter-workspace-dir-case", {
+    "package.json": JSON.stringify({
+      name: "test-workspace",
+      workspaces: ["packages/*"],
+      private: true,
+    }),
+    // Directory name is lowercase but package name has mixed case
+    "packages/mixedcase/package.json": JSON.stringify({
+      name: "MixedCase",
+      version: "1.0.0",
+      scripts: {
+        test: "echo 'MixedCase directory test passed'",
+      },
+    }),
+  });
+
+  // Install workspace dependencies
+  const proc = Bun.spawn({
+    cmd: [bunExe(), "install"],
+    env: bunEnv,
+    cwd: dir,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  await proc.exited;
+
+  // Test filtering by package name (not directory name)
+  const proc2 = Bun.spawn({
+    cmd: [bunExe(), "run", "--filter", "MixedCase", "test"],
+    env: bunEnv,
+    cwd: dir,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([
+    proc2.stdout.text(),
+    proc2.stderr.text(),
+    proc2.exited,
+  ]);
+
+  expect(exitCode).toBe(0);
+  expect(stdout).toContain("MixedCase directory test passed");
+  expect(stderr).not.toContain("error: ENOENT");
+});