Implement additional_linker_inputs attr

Author: adincebic

swift/internal/binary_attrs.bzl

@@ -59,6 +59,16 @@ def binary_rule_attrs(
             requires_srcs = False,
         ),
         {
+            "additional_linker_inputs": attr.label_list(
+                allow_files = True,
+                doc = """\
+List of additional files needed by the linker.
+
+These files will be passed to the linker when linking the binary target.
+Typically, these are linker scripts or other files referenced by `linkopts`.
+""",
+                mandatory = False,
+            ),
             "linkopts": attr.string_list(
                 doc = """\
 Additional linker options that should be passed to `clang`. These strings are

swift/swift_binary.bzl

@@ -157,7 +157,7 @@ def _swift_binary_impl(ctx):
     binary_link_flags = expand_locations(
         ctx,
         ctx.attr.linkopts,
-        ctx.attr.swiftc_inputs,
+        ctx.attr.swiftc_inputs + ctx.attr.additional_linker_inputs,
     ) + ctx.fragments.cpp.linkopts
 
     # When linking the binary, make sure we use the correct entry point name.
@@ -178,7 +178,7 @@ def _swift_binary_impl(ctx):
 
     linking_outputs = register_link_binary_action(
         actions = ctx.actions,
-        additional_inputs = ctx.files.swiftc_inputs,
+        additional_inputs = ctx.files.swiftc_inputs + ctx.files.additional_linker_inputs,
         additional_linking_contexts = additional_linking_contexts,
         additional_outputs = additional_debug_outputs,
         feature_configuration = feature_configuration,
@@ -228,7 +228,7 @@ def _swift_binary_impl(ctx):
             environment = expand_locations(
                 ctx,
                 ctx.attr.env,
-                ctx.attr.swiftc_inputs,
+                ctx.attr.swiftc_inputs + ctx.attr.additional_linker_inputs,
             ),
         ),
     ]
@@ -240,7 +240,7 @@ def _swift_binary_impl(ctx):
         linking_context, _ = (
             create_linking_context_from_compilation_outputs(
                 actions = ctx.actions,
-                additional_inputs = ctx.files.swiftc_inputs,
+                additional_inputs = ctx.files.swiftc_inputs + ctx.files.additional_linker_inputs,
                 alwayslink = True,
                 compilation_outputs = compilation_outputs,
                 feature_configuration = feature_configuration,

test/BUILD

@@ -1,4 +1,5 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+load(":additional_linker_inputs_tests.bzl", "additional_linker_inputs_test_suite")
 load(":ast_file_tests.bzl", "ast_file_test_suite")
 load(":bzl_test.bzl", "bzl_test")
 load(":cc_library_tests.bzl", "cc_library_test_suite")
@@ -30,6 +31,8 @@ load(":xctest_runner_tests.bzl", "xctest_runner_test_suite")
 
 licenses(["notice"])
 
+additional_linker_inputs_test_suite(name = "additional_linker_inputs")
+
 ast_file_test_suite(name = "ast_file")
 
 cc_library_test_suite(name = "cc_library")

test/additional_linker_inputs_tests.bzl

@@ -0,0 +1,104 @@
+"""Tests for swift_binary's additional_linker_inputs attribute."""
+
+load("@bazel_skylib//lib:unittest.bzl", "analysistest", "unittest")
+
+def _swift_binary_additional_linker_inputs_test_impl(ctx):
+    env = analysistest.begin(ctx)
+
+    actions = analysistest.target_actions(env)
+    link_actions = [
+        action
+        for action in actions
+        if action.mnemonic == "CppLink"
+    ]
+
+    if not link_actions:
+        unittest.fail(
+            env,
+            "Expected to find a CppLink action but found none. Available actions: {}".format(
+                [action.mnemonic for action in actions],
+            ),
+        )
+        return analysistest.end(env)
+
+    if len(link_actions) != 1:
+        unittest.fail(
+            env,
+            "Expected exactly one CppLink action, but found {}".format(len(link_actions)),
+        )
+        return analysistest.end(env)
+
+    link_action = link_actions[0]
+
+    expected_inputs = ctx.attr.expected_additional_inputs
+    expected_linkopts = ctx.attr.expected_linkopts
+
+    action_input_paths = set([input.short_path for input in link_action.inputs.to_list()])
+
+    if expected_inputs:
+        missing_inputs = set(expected_inputs) - action_input_paths
+        if missing_inputs:
+            unittest.fail(
+                env,
+                "Missing expected additional linker inputs: {}. Available inputs: {}".format(
+                    sorted(missing_inputs),
+                    sorted(action_input_paths),
+                ),
+            )
+
+    if expected_linkopts:
+        missing_linkopts = []
+        for expected_linkopt in expected_linkopts:
+            # Use substring match since -Wl, options may be grouped with other flags
+            found = False
+            for arg in link_action.argv:
+                if expected_linkopt in arg:
+                    found = True
+                    break
+            if not found:
+                missing_linkopts.append(expected_linkopt)
+
+        if missing_linkopts:
+            unittest.fail(
+                env,
+                "Missing expected linkopts: {}. Link arguments were: {}".format(
+                    missing_linkopts,
+                    link_action.argv,
+                ),
+            )
+
+    return analysistest.end(env)
+
+swift_binary_additional_linker_inputs_test = analysistest.make(
+    _swift_binary_additional_linker_inputs_test_impl,
+    attrs = {
+        "expected_additional_inputs": attr.string_list(
+        ),
+        "expected_linkopts": attr.string_list(
+        ),
+    },
+)
+
+def additional_linker_inputs_test_suite(name, tags = []):
+    all_tags = [name] + tags
+
+    swift_binary_additional_linker_inputs_test(
+        name = "{}_with_additional_inputs".format(name),
+        target_under_test = "//test/fixtures/linking:bin_with_additional_linker_inputs",
+        expected_additional_inputs = ["test/fixtures/linking/test_data.bin"],
+        expected_linkopts = ["-Wl,-sectcreate,__TEXT,__test_section"],
+        tags = all_tags,
+    )
+
+    swift_binary_additional_linker_inputs_test(
+        name = "{}_without_additional_inputs".format(name),
+        target_under_test = "//test/fixtures/linking:bin_without_additional_linker_inputs",
+        expected_additional_inputs = [],
+        expected_linkopts = [],
+        tags = all_tags,
+    )
+
+    native.test_suite(
+        name = name,
+        tags = all_tags,
+    )

test/fixtures/linking/BUILD

@@ -34,6 +34,29 @@ cc_binary(
     deps = [":lib"],
 )
 
+swift_binary(
+    name = "bin_with_additional_linker_inputs",
+    srcs = ["main.swift"],
+    additional_linker_inputs = ["test_data.bin"],
+    linkopts = [
+        "-Wl,-sectcreate,__TEXT,__test_section,$(execpath test_data.bin)",
+    ],
+    tags = FIXTURE_TAGS,
+)
+
+swift_binary(
+    name = "bin_with_empty_additional_linker_inputs",
+    srcs = ["main.swift"],
+    additional_linker_inputs = [],
+    tags = FIXTURE_TAGS,
+)
+
+swift_binary(
+    name = "bin_without_additional_linker_inputs",
+    srcs = ["main.swift"],
+    tags = FIXTURE_TAGS,
+)
+
 bzl_library(
     name = "fake_framework",
     srcs = ["fake_framework.bzl"],

test/fixtures/linking/test_data.bin

@@ -0,0 +1 @@
+TEST_DATA_FOR_ADDITIONAL_LINKER_INPUTS