Fix reflection.fbs import path

We need to copy the .fbs files into the package used for .bfbs files.
This is necessary as flatc doesn't provide support to specify the full
output file name for an .fbs file in a different folder.
I tried OUTPUT_FILE env var but this doesn't seem to be honored by
flatc.

build_defs.bzl

@@ -152,12 +152,34 @@ def flatbuffer_library_public(
             "done",
         ])
         reflection_outs = [
-            (out_prefix + "%s.bfbs") % (s.replace(".fbs", "").split("/")[-1])
+            (out_prefix + "%s.bfbs") % (native.package_relative_label(s).name.removesuffix(".fbs"))
             for s in srcs
         ]
+
+        # Flatc generates the output file name based on the input basename
+        # So in order to generate the .bfbs file in the current package
+        # we need to copy the .fbs files into the package as well
+        srcs_reflection = []
+        for s in srcs:
+            label_src = native.package_relative_label(s)
+            label_in_current_package = native.package_relative_label(":invalid")
+            if label_src.repo_name != label_in_current_package.repo_name or label_src.package != label_in_current_package.package:
+                if not label_src.name.endswith(".fbs"):
+                    fail("Filegroups in srcs are only supported for the current package")
+                copied_src_label = "copy_" + label_src.name
+                native.genrule(
+                    name = copied_src_label,
+                    srcs = [s],
+                    outs = [label_src.name],
+                    cmd = "cp $< $@",
+                )
+                srcs_reflection.append(copied_src_label)
+            else:
+                srcs_reflection.append(s)
+
         native.genrule(
             name = "%s_srcs" % reflection_name,
-            srcs = srcs + includes,
+            srcs = srcs_reflection + includes,
             outs = reflection_outs,
             output_to_bindir = output_to_bindir,
             tools = [TRUE_FLATC_PATH],

reflection/BUILD.bazel

@@ -7,6 +7,12 @@ filegroup(
     visibility = ["//visibility:public"],
 )
 
+# Needed by build_defs.bzl to copy the file to the evaluating package
+exports_files(
+    srcs = ["reflection.fbs"],
+    visibility = ["//visibility:public"],
+)
+
 filegroup(
     name = "reflection_fbs_schema",
     srcs = ["reflection.fbs"],

reflection/ts/BUILD.bazel

@@ -1,15 +1,18 @@
 load("//:typescript.bzl", "flatbuffer_ts_library")
 
-genrule(
-    name = "copy_schema_to_folder",
-    srcs = ["//reflection:reflection_fbs_schema"],
-    outs = ["reflection.fbs"],
-    cmd = "cp $< $@",
-)
+# Flatc generates the output file name based on the input basename
+# So in order to generate reflection/ts/reflection_fbs_schema.bfbs
+# we need to copy reflection/reflection.fbs to reflection/ts/reflection.fbs.
+# genrule(
+#     name = "copy_schema_to_folder",
+#     srcs = ["//reflection:reflection_fbs_schema"],
+#     outs = ["reflection.fbs"],
+#     cmd = "cp $< $@",
+# )
 
 flatbuffer_ts_library(
     name = "reflection_ts_fbs",
-    srcs = [":reflection.fbs"],
+    srcs = ["//reflection:reflection.fbs"],
     gen_reflections = True,
     visibility = ["//visibility:public"],
 )

tests/ts/BUILD.bazel

@@ -18,6 +18,7 @@ flatbuffer_ts_library(
     name = "typescript_ts_fbs",
     srcs = ["typescript_keywords.fbs"],
     deps = [
+        "//reflection/ts:reflection_ts_fbs",
         "//tests/ts/test_dir:include_ts_fbs",
         "//tests/ts/test_dir:typescript_transitive_ts_fbs",
     ],

typescript.bzl

@@ -47,7 +47,7 @@ def flatbuffer_ts_library(
         reflection binaries for the schemas.
     """
     srcs_lib = "%s_srcs" % (name)
-    out_base = [s.replace(".fbs", "").split("/")[-1].split(":")[-1] for s in srcs]
+    out_base = [native.package_relative_label(s).name.removesuffix(".fbs") for s in srcs]
 
     if len(srcs) != 1:
         fail("flatbuffer_ts_library only supports one .fbs file per target currently.")