Fix unstripped roots in multi-configuration builds

rustdoc_test fails when its crate dependency and its toolchain
dependency are from different configurations, because the stripped roots
did not include any toolchain files.

This change simplifies the logic by collecting roots from all the
inputs.

Author: yuzhy8701

rust/private/rustdoc_test.bzl

@@ -20,7 +20,7 @@ load("//rust/private:providers.bzl", "CrateInfo")
 load("//rust/private:rustdoc.bzl", "rustdoc_compile_action")
 load("//rust/private:utils.bzl", "dedent", "find_toolchain", "transform_deps")
 
-def _construct_writer_arguments(ctx, test_runner, opt_test_params, action, crate_info):
+def _construct_writer_arguments(ctx, test_runner, opt_test_params, action):
     """Construct arguments and environment variables specific to `rustdoc_test_writer`.
 
     This is largely solving for the fact that tests run from a runfiles directory
@@ -32,7 +32,6 @@ def _construct_writer_arguments(ctx, test_runner, opt_test_params, action, crate
         test_runner (File): The test_runner output file declared by `rustdoc_test`.
         opt_test_params (File): An output file we can optionally use to store params for `rustdoc`.
         action (struct): Action arguments generated by `rustdoc_compile_action`.
-        crate_info (CrateInfo): The provider of the crate who's docs are being tested.
 
     Returns:
         tuple: A tuple of `rustdoc_test_writer` specific inputs
@@ -64,29 +63,13 @@ def _construct_writer_arguments(ctx, test_runner, opt_test_params, action, crate
 
     # Collect and dedupe all of the file roots in a list before appending
     # them to args to prevent generating a large amount of identical args
-    roots = []
-    root = crate_info.output.root.path
-    if not root in roots:
-        roots.append(root)
-    for dep in crate_info.deps.to_list() + crate_info.proc_macro_deps.to_list():
-        dep_crate_info = getattr(dep, "crate_info", None)
-        dep_dep_info = getattr(dep, "dep_info", None)
-        if dep_crate_info:
-            root = dep_crate_info.output.root.path
-            if not root in roots:
-                roots.append(root)
-        if dep_dep_info:
-            for direct_dep in dep_dep_info.direct_crates.to_list():
-                root = direct_dep.dep.output.root.path
-                if not root in roots:
-                    roots.append(root)
-            for transitive_dep in dep_dep_info.transitive_crates.to_list():
-                root = transitive_dep.output.root.path
-                if not root in roots:
-                    roots.append(root)
-
-    for root in roots:
-        writer_args.add("--strip_substring={}/".format(root))
+    roots = {}
+    for input in action.inputs.to_list():
+        roots[input.root.path] = None
+
+    for root in roots.keys():
+        if root:
+            writer_args.add("--strip_substring={}/".format(root))
 
     # Indicate that the rustdoc_test args are over.
     writer_args.add("--")
@@ -165,7 +148,6 @@ def _rust_doc_test_impl(ctx):
         test_runner = test_runner,
         opt_test_params = opt_test_params,
         action = action,
-        crate_info = crate_info,
     )
 
     # Allow writer environment variables to override those from the action.