Fix resource_strip_prefix of scala_libary for external repositories (#944)

* Fix resource_strip_prefix of scala_libary for external repositories

If repository `A` has a `scala_library` with `resources` and
`resource_strip_prefix` on which repository `B` depends then repository
`B` fails to build complaining that resource doesn't start with correct
prefix

* Push prefix handling down to _adjust_resources_path_by_strip_prefix
Use skylib to concat paths

* Rewrite test with the external repo
This reflects situation described in PR

* Run buildifier

* Revert external repository

* Revrite test with local_repository

* Revert visiblity of scala_library

Author: simuons

WORKSPACE

@@ -126,6 +126,11 @@ filegroup(
     path = "third_party/test/new_local_repo",
 )
 
+local_repository(
+    name = "strip_resource_external_workspace",
+    path = "third_party/test/strip_resource_external_workspace",
+)
+
 load("@io_bazel_rules_scala//scala:toolchains.bzl", "scala_register_unused_deps_toolchains")
 
 scala_register_unused_deps_toolchains()

scala/private/phases/phase_compile.bzl

@@ -3,6 +3,7 @@
 #
 # DOCUMENT THIS
 #
+load("@bazel_skylib//lib:paths.bzl", _paths = "paths")
 load("@bazel_tools//tools/jdk:toolchain_utils.bzl", "find_java_runtime_toolchain", "find_java_toolchain")
 load(
     "@io_bazel_rules_scala//scala/private:coverage_replacements_provider.bzl",
@@ -480,17 +481,17 @@ def _try_to_compile_java_jar(
         java_compilation_provider = provider,
     )
 
-def _adjust_resources_path(path, resource_strip_prefix):
+def _adjust_resources_path(resource, resource_strip_prefix):
     if resource_strip_prefix:
-        return _adjust_resources_path_by_strip_prefix(path, resource_strip_prefix)
+        return _adjust_resources_path_by_strip_prefix(resource, resource_strip_prefix)
     else:
-        return _adjust_resources_path_by_default_prefixes(path)
+        return _adjust_resources_path_by_default_prefixes(resource.path)
 
 def _add_resources_cmd(ctx):
     res_cmd = []
     for f in ctx.files.resources:
         c_dir, res_path = _adjust_resources_path(
-            f.short_path,
+            f,
             ctx.attr.resource_strip_prefix,
         )
         target_path = res_path
@@ -504,12 +505,14 @@ def _add_resources_cmd(ctx):
         res_cmd.extend([line])
     return "".join(res_cmd)
 
-def _adjust_resources_path_by_strip_prefix(path, resource_strip_prefix):
-    if not path.startswith(resource_strip_prefix):
-        fail("Resource file %s is not under the specified prefix to strip" % path)
+def _adjust_resources_path_by_strip_prefix(resource, resource_strip_prefix):
+    path = resource.path
+    prefix = _paths.join(resource.owner.workspace_root, resource_strip_prefix)
+    if not path.startswith(prefix):
+        fail("Resource file %s is not under the specified prefix %s to strip" % (path, prefix))
 
-    clean_path = path[len(resource_strip_prefix):]
-    return resource_strip_prefix, clean_path
+    clean_path = path[len(prefix):]
+    return prefix, clean_path
 
 def _collect_java_providers_of(deps):
     providers = []

test/src/main/scala/scalarules/test/resources/strip/BUILD

@@ -14,3 +14,12 @@ scala_specs2_junit_test(
     unused_dependency_checker_mode = "off",
     deps = [":noSrcsWithResources"],
 )
+
+scala_specs2_junit_test(
+    name = "resouceStripPrefixFromExternalRepoTest",
+    size = "small",
+    srcs = ["ResourceStripPrefixTest.scala"],
+    suffixes = ["Test"],
+    unused_dependency_checker_mode = "off",
+    deps = ["@strip_resource_external_workspace//strip:noSrcsWithResources"],
+)

third_party/test/strip_resource_external_workspace/WORKSPACE

@@ -0,0 +1 @@
+workspace(name = "strip_resource_external_workspace")

third_party/test/strip_resource_external_workspace/strip/BUILD.bazel

@@ -0,0 +1,8 @@
+load("@io_bazel_rules_scala//scala:scala.bzl", "scala_library")
+
+scala_library(
+    name = "noSrcsWithResources",
+    resource_strip_prefix = "strip",
+    resources = ["nosrc_jar_resource.txt"],
+    visibility = ["//visibility:public"],
+)

third_party/test/strip_resource_external_workspace/strip/nosrc_jar_resource.txt

@@ -0,0 +1 @@
+I am a text resource!