Updated internal documentation (#823)

Author: UebelAndre

rust/private/repository_utils.bzl

@@ -484,9 +484,14 @@ def produce_tool_path(tool_name, target_triple, version):
 def load_arbitrary_tool(ctx, tool_name, tool_subdirectories, version, iso_date, target_triple, sha256 = ""):
     """Loads a Rust tool, downloads, and extracts into the common workspace.
 
-    This function sources the tool from the Rust-lang static file server. The index is available
-    at: https://static.rust-lang.org/dist/index.html (or the path specified by
-    "${STATIC_RUST_URL}/dist/index.html" if the STATIC_RUST_URL envinronment variable is set).
+    This function sources the tool from the Rust-lang static file server. The index is available at:
+    - https://static.rust-lang.org/dist/channel-rust-stable.toml
+    - https://static.rust-lang.org/dist/channel-rust-beta.toml
+    - https://static.rust-lang.org/dist/channel-rust-nightly.toml
+
+    The environment variable `STATIC_RUST_URL` can be used to replace the schema and hostname of
+    the URLs used for fetching assets. `https://static.rust-lang.org/dist/channel-rust-stable.toml`
+    becomes `${STATIC_RUST_URL}/dist/channel-rust-stable.toml`
 
     Args:
         ctx (repository_ctx): A repository_ctx (no attrs required).
@@ -511,7 +516,7 @@ def load_arbitrary_tool(ctx, tool_name, tool_subdirectories, version, iso_date,
 
     check_version_valid(version, iso_date, param_prefix = tool_name + "_")
 
-    # N.B. See https://static.rust-lang.org/dist/index.html to find the tool_suburl for a given
+    # View the indices mentioned in the docstring to find the tool_suburl for a given
     # tool.
     tool_suburl = produce_tool_suburl(tool_name, target_triple, version, iso_date)
     static_rust = ctx.os.environ.get("STATIC_RUST_URL", "https://static.rust-lang.org")

rust/toolchain.bzl

@@ -83,6 +83,17 @@ rust_stdlib_filegroup = rule(
 )
 
 def _ltl(library, ctx, cc_toolchain, feature_configuration):
+    """A helper to generate `LibraryToLink` objects
+
+    Args:
+        library (File): A rust library file to link.
+        ctx (ctx): The rule's context object.
+        cc_toolchain (CcToolchainInfo): A cc toolchain provider to be used.
+        feature_configuration (feature_configuration): feature_configuration to be queried.
+
+    Returns:
+        LibraryToLink: A provider containing information about libraries to link.
+    """
     return cc_common.create_library_to_link(
         actions = ctx.actions,
         feature_configuration = feature_configuration,