From 1eae40f048f619a7cc53267fae1716877041e6d1 Mon Sep 17 00:00:00 2001
From: Marcel Hlopko <hlopko@google.com>
Date: Sun, 3 Nov 2019 21:49:10 +0100
Subject: [PATCH] Propagate linkopts

---
 WORKSPACE                          | 10 ++++---
 rust/private/rustc.bzl             | 14 ++++++++++
 test/analysis/BUILD                |  3 +++
 test/analysis/native_deps_test.bzl | 42 ++++++++++++++++++++++++++++++
 4 files changed, 66 insertions(+), 3 deletions(-)
 create mode 100644 test/analysis/BUILD
 create mode 100644 test/analysis/native_deps_test.bzl

diff --git a/WORKSPACE b/WORKSPACE
index c97ce18878..59e3dafc7a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -19,10 +19,14 @@ local_repository(
 
 http_archive(
     name = "bazel_skylib",
-    sha256 = "eb5c57e4c12e68c0c20bc774bfbc60a568e800d025557bc4ea022c6479acc867",
-    strip_prefix = "bazel-skylib-0.6.0",
-    url = "https://github.com/bazelbuild/bazel-skylib/archive/0.6.0.tar.gz",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.0.2/bazel-skylib-1.0.2.tar.gz",
+        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.0.2/bazel-skylib-1.0.2.tar.gz",
+    ],
+    sha256 = "97e70364e9249702246c0e9444bccdc4b847bed1eb03c5a3ece4f83dfe6abc44",
 )
+load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
+bazel_skylib_workspace()
 
 # TODO: Move this to examples/WORKSPACE when recursive repositories are enabled.
 load("@io_bazel_rules_rust//rust:repositories.bzl", "rust_repositories")
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index 0839ae407a..8c3472e7fb 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -44,6 +44,7 @@ DepInfo = provider(
         "transitive_dylibs": "depset[File]",
         "transitive_staticlibs": "depset[File]",
         "transitive_libs": "List[File]: All transitive dependencies, not filtered by type.",
+        "linkopts": "list[string]",
     },
 )
 
@@ -101,6 +102,7 @@ def collect_deps(deps, toolchain):
     transitive_crates = depset()
     transitive_dylibs = depset(order = "topological")  # dylib link flag ordering matters.
     transitive_staticlibs = depset()
+    linkopts = []
     for dep in deps:
         if CrateInfo in dep:
             # This dependency is a rust_library
@@ -114,10 +116,20 @@ def collect_deps(deps, toolchain):
 
             # TODO: We could let the user choose how to link, instead of always preferring to link static libraries.
             libs = get_libs_for_static_executable(dep)
+            # TODO: This is changing the order of linker inputs, it shouldn't.
+            # In more sophisticated scenarios we need to retain the relative
+            # order of static/shared libraries. Imagine following libs:
+            #   libs = [ liba.a, libb.so, libc.a ]
+            # Ideally this will get converted into the following linker command
+            # line:
+            #   -la -lb -lc
+            # But the current implementation produces:
+            #    -la -lc -b
             dylibs = [l for l in libs.to_list() if l.basename.endswith(toolchain.dylib_ext)]
             staticlibs = [l for l in libs.to_list() if l.basename.endswith(toolchain.staticlib_ext)]
             transitive_dylibs = depset(transitive = [transitive_dylibs, depset(dylibs)])
             transitive_staticlibs = depset(transitive = [transitive_staticlibs, depset(staticlibs)])
+            linkopts.extend(dep[CcInfo].linking_context.user_link_flags)
         else:
             fail("rust targets can only depend on rust_library, rust_*_library or cc_library targets." + str(dep), "deps")
 
@@ -132,6 +144,7 @@ def collect_deps(deps, toolchain):
         transitive_dylibs = transitive_dylibs,
         transitive_staticlibs = transitive_staticlibs,
         transitive_libs = transitive_libs.to_list(),
+        linkopts = linkopts,
     )
 
 def _get_linker_and_args(ctx, rpaths):
@@ -399,6 +412,7 @@ def add_native_link_flags(args, dep_info):
     args.add_all(native_libs, map_each = _get_dirname, uniquify = True, format_each = "-Lnative=%s")
     args.add_all(dep_info.transitive_dylibs, map_each = get_lib_name, format_each = "-ldylib=%s")
     args.add_all(dep_info.transitive_staticlibs, map_each = get_lib_name, format_each = "-lstatic=%s")
+    args.add_all(dep_info.linkopts, uniquify = False)
 
 def _get_dirname(file):
     return file.dirname
diff --git a/test/analysis/BUILD b/test/analysis/BUILD
new file mode 100644
index 0000000000..ba430fadec
--- /dev/null
+++ b/test/analysis/BUILD
@@ -0,0 +1,3 @@
+load(":native_deps_test.bzl", "native_deps_test_suite")
+
+native_deps_test_suite(name = "native_deps_test_suite")
diff --git a/test/analysis/native_deps_test.bzl b/test/analysis/native_deps_test.bzl
new file mode 100644
index 0000000000..458f90ae3b
--- /dev/null
+++ b/test/analysis/native_deps_test.bzl
@@ -0,0 +1,42 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+load("@bazel_skylib//lib:unittest.bzl", "analysistest", "asserts")
+load("//rust:rust.bzl", "rust_binary")
+
+def _linkopts_test_impl(ctx):
+    env = analysistest.begin(ctx)
+
+    subject = analysistest.target_under_test(env)
+    actions = analysistest.target_actions(env)
+
+    asserts.true(env, "-lsystem_lib" in actions[0].argv)
+
+    return analysistest.end(env)
+
+linkopts_test = analysistest.make(_linkopts_test_impl)
+
+def _linkopts_test():
+    cc_library(
+        name = "native",
+        linkopts = ["-lsystem_lib"],
+        tags = ["manual"],
+    )
+    rust_binary(
+        name = "main",
+        deps = [":native"],
+        srcs = ["main.rs"],
+        tags = ["manual"],
+    )
+    linkopts_test(
+        name = "linkopts_test",
+        target_under_test = ":main",
+    )
+
+def native_deps_test_suite(name):
+    _linkopts_test()
+
+    native.test_suite(
+        name = name,
+        tests = [
+            ":linkopts_test",
+        ],
+    )