`rust_bindgen` rejects `CcInfo` dependencies with only a dynamic library

[backtr4ce]

Description

rust_bindgen fails during analysis when its cc_lib supplies a LibraryToLink containing a dynamic_library but no static library.

The current implementation handles static_library and pic_static_library, but does not handle dynamic_library. As a result, it reports that no static libraries were found.

Reproduction steps

MODULE.bazel:

module(name = "repro")

bazel_dep(name = "rules_cc", version = "0.2.22")
bazel_dep(name = "rules_rust", version = "0.73.0")
bazel_dep(name = "rules_rust_bindgen", version = "0.73.0")

register_toolchains("//:bindgen_toolchain")

BUILD.bazel:

load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_import", "cc_library", "cc_shared_library")
load("@rules_rust_bindgen//:defs.bzl", "rust_bindgen", "rust_bindgen_toolchain")

cc_binary(
    name = "fake_bindgen",
    srcs = ["fake_bindgen.c"],
)

rust_bindgen_toolchain(
    name = "bindgen_toolchain_impl",
    bindgen = ":fake_bindgen",
    default_rustfmt = False,
)

toolchain(
    name = "bindgen_toolchain",
    toolchain = ":bindgen_toolchain_impl",
    toolchain_type = "@rules_rust_bindgen//:toolchain_type",
)

cc_library(
    name = "foo_objects",
    srcs = ["foo.c"],
    hdrs = ["foo.h"],
)

cc_shared_library(
    name = "foo_shared",
    deps = [":foo_objects"],
)

cc_import(
    name = "foo",
    hdrs = ["foo.h"],
    shared_library = ":foo_shared",
)

rust_bindgen(
    name = "bindings",
    cc_lib = ":foo",
    header = "foo.h",
)

foo.h:

int foo(void);

fake_bindgen.c:

int main(void) {
    return 0;
}

foo.c:

#include "foo.h"

int foo(void) {
    return 42;
}

Run:

bazel build --nobuild //:bindings

The build fails during analysis with:

Error in fail: No static libraries found in @@//:foo

Impact

This blocks rust_bindgen for C/C++ dependencies that are available only as dynamic libraries. Using a static version of the dependency is a workaround when one is available.

Bazel and rules_rust version

• Bazel: 9.2.0
• rules_rust: 0.73.0
• rules_rust_bindgen: 0.73.0

[backtr4ce]

This fixes it for me:

--- a/private/bindgen.bzl
+++ b/private/bindgen.bzl
@@ -156,6 +156,10 @@
                 rustc_flags.append("-lstatic={}".format(get_lib_name_default(lib.pic_static_library)))
                 linker_search_paths.append(lib.pic_static_library.dirname)
                 compile_data.append(lib.pic_static_library)
+            elif lib.dynamic_library:
+                rustc_flags.append("-ldylib={}".format(get_lib_name_default(lib.dynamic_library)))
+                linker_search_paths.append(lib.dynamic_library.dirname)
+                compile_data.append(lib.dynamic_library)
 
     if not compile_data:
         fail("No static libraries found in {}".format(