Support annotation link dependencies

Author: finn-ball

rs/extensions.bzl

@@ -340,6 +340,8 @@ crate.annotation(
             deps = annotation.deps,
             crate_tags = annotation.tags,
             deps_select = _select(feature_resolutions.deps),
+            link_deps = annotation.link_deps,
+            link_deps_select = annotation.link_deps_select,
             aliases = feature_resolutions.aliases,
             crate_features = annotation.crate_features,
             crate_features_select = _select(feature_resolutions.features_enabled),
@@ -1006,6 +1008,12 @@ _annotation = tag_class(
         "deps": attr.label_list(
             doc = "A list of labels to add to a crate's `rust_library::deps` attribute.",
         ),
+        "link_deps": attr.string_list(
+            doc = "Labels to add to a crate's `rust_library::link_deps` attribute.",
+        ),
+        "link_deps_select": attr.string_list_dict(
+            doc = "Labels to add to a crate's `rust_library::link_deps` attribute, keyed by platform triplet.",
+        ),
         "tags": attr.string_list(
             doc = "A list of tags to add to a crate's generated targets.",
         ),

rs/private/annotations.bzl

@@ -14,6 +14,8 @@ def _crate_annotation(
         build_script_tags = [],
         data = [],
         deps = [],
+        link_deps = [],
+        link_deps_select = {},
         tags = [],
         crate_features = [],
         crate_features_select = {},
@@ -42,6 +44,8 @@ def _crate_annotation(
         build_script_tags = build_script_tags,
         data = data,
         deps = deps,
+        link_deps = link_deps,
+        link_deps_select = link_deps_select,
         tags = tags,
         crate_features = crate_features,
         crate_features_select = crate_features_select,

rs/private/repository_utils.bzl

@@ -176,6 +176,9 @@ _RUST_CRATE_MACRO_CALL = """{indent}rust_crate(
 {indent}    deps = [
 {indent}        {deps}
 {indent}    ]{extra_deps}{conditional_deps},
+{indent}    link_deps = [
+{indent}        {link_deps}
+{indent}    ]{conditional_link_deps},
 {indent}    data = [
 {indent}        {data}
 {indent}    ],
@@ -220,6 +223,11 @@ def render_rust_crate_call(attr, values, bazel_metadata = {}, extra_deps = "", i
     rustc_flags, conditional_rustc_flags = render_select(attr.rustc_flags, attr.rustc_flags_select, use_legacy_rules_rust_platforms)
     deps, conditional_deps = render_select(attr.deps + bazel_metadata.get("deps", []), attr.deps_select, use_legacy_rules_rust_platforms)
     build_script_env_files = getattr(attr, "build_script_env_files", []) + ["cargo_toml_env_vars.env"]
+    link_deps, conditional_link_deps = render_select(
+        getattr(attr, "link_deps", []),
+        getattr(attr, "link_deps_select", {}),
+        use_legacy_rules_rust_platforms,
+    )
 
     conditional_build_script_env = render_select_build_script_env(attr.build_script_env_select, use_legacy_rules_rust_platforms)
 
@@ -250,6 +258,8 @@ def render_rust_crate_call(attr, values, bazel_metadata = {}, extra_deps = "", i
         deps = list_indent.join(['"%s"' % d for d in sorted(deps)]),
         extra_deps = extra_deps,
         conditional_deps = " + " + conditional_deps if conditional_deps else "",
+        link_deps = list_indent.join(['"%s"' % d for d in sorted(link_deps)]),
+        conditional_link_deps = " + " + conditional_link_deps if conditional_link_deps else "",
         data = list_indent.join(['"%s"' % str(d) for d in attr.data]),
         extra_compile_data_attr = extra_compile_data_attr,
         crate_features = repr(sorted(crate_features)),
@@ -322,6 +332,8 @@ rust_crate_attrs = {
     "data": attr.label_list(),
     "deps": attr.label_list(),
     "deps_select": _label_list_dict(),
+    "link_deps": attr.string_list(),
+    "link_deps_select": attr.string_list_dict(),
     "aliases": attr.string_dict(),
     "crate_features": attr.string_list(),
     "crate_features_select": attr.string_list_dict(),

rs/rust_crate.bzl

@@ -21,6 +21,7 @@ def rust_crate(
         version,
         aliases,
         deps,
+        link_deps,
         data,
         crate_features,
         triples,
@@ -205,8 +206,10 @@ def rust_crate(
         )
 
         if is_proc_macro:
+            # rust_proc_macro intentionally does not support link_deps.
             (_rust_proc_macro if skip_deps_verification else rust_proc_macro)(**kwargs)
         else:
+            kwargs["link_deps"] = link_deps
             (_rust_library if skip_deps_verification else rust_library)(**kwargs)
 
     binary_lib_dep = [name] if has_lib else []
@@ -216,6 +219,7 @@ def rust_crate(
             compile_data = compile_data,
             aliases = aliases,
             deps = binary_lib_dep + deps,
+            link_deps = link_deps,
             data = data,
             crate_features = crate_features,
             crate_root = crate_root,