fix: fix a bug where yq failed to build in the root package

BUILD.bazel

@@ -1,6 +1,7 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
 load("@bazel_gazelle//:def.bzl", "gazelle", "gazelle_binary")
 load("//lib:write_source_files.bzl", "write_source_files")
+load("//lib:yq.bzl", "yq")
 
 gazelle_binary(
     name = "gazelle_bin",
@@ -35,3 +36,10 @@ write_source_files(
     diff_test = False,
     files = {"test-out/dist/write_source_file_root-test": ":write_source_file_root"},
 )
+
+# Test that yq works in the root package
+yq(
+    name = "yq_root-test",
+    srcs = ["//lib/tests/yq:a.yaml"],
+    expression = ".",
+)

lib/private/yq.bzl

@@ -40,7 +40,7 @@ def _yq_impl(ctx):
 
     # For split operations, yq outputs files in the same directory so we
     # must cd to the correct output dir before executing it
-    bin_dir = ctx.bin_dir.path + "/" + ctx.label.package
+    bin_dir = "/".join([ctx.bin_dir.path, ctx.label.package]) if ctx.label.package else ctx.bin_dir.path
     escape_bin_dir = _escape_path(bin_dir)
     cmd = "cd {bin_dir} && {yq} {args} {eval_cmd} {expression} {sources} {maybe_out}".format(
         bin_dir = ctx.bin_dir.path + "/" + ctx.label.package,

lib/tests/yq/BUILD.bazel

@@ -1,6 +1,13 @@
 load("//lib/private:diff_test.bzl", "diff_test")
 load("//lib:yq.bzl", "yq")
 
+exports_files(
+    [
+        "a.yaml",
+    ],
+    visibility = ["//visibility:public"],
+)
+
 # Identity (dot) expression produces identical yaml
 yq(
     name = "case_dot_expression",