fix: allow implementation files in modules

cpp/private/target_rules.bzl

@@ -2,13 +2,13 @@
 Contains rules implementations for building C++ targets
 """
 
+load("@bazel_tools//tools/build_defs/cc:action_names.bzl", "ACTION_NAMES")
 load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
 load("//cpp:providers.bzl", "CppModuleInfo")
 load("//cpp/private:common.bzl", "collect_external_headers", "collect_external_includes", "collect_module_objects", "collect_modules", "get_compile_command_args", "resolve_linker_arguments")
 load("//cpp/private:extra_actions.bzl", "EXTRA_ACTIONS")
 load("//cpp/private/actions:compile.bzl", "cpp_compile")
 load("//cpp/private/actions:strip.bzl", "cpp_strip_binary", "cpp_strip_objects")
-load("@bazel_tools//tools/build_defs/cc:action_names.bzl", "ACTION_NAMES")
 
 def _has_agressive_strip(features, _toolchain):
     # FIXME(alexbatashev): does not work with default toolchain
@@ -165,7 +165,13 @@ def module_impl(ctx):
         progress_message = "Precompiling %{output}",
     )
 
-    obj_files = cpp_compile(ctx.files.srcs + [pcm], headers, includes, modules, features, toolchain, module_srcs = ctx.files.interface)
+    cur_module = {
+        "name": ctx.attr.module_name,
+        "file": pcm,
+        "source": ctx.files.interface[0],
+    }
+
+    obj_files = cpp_compile(ctx.files.srcs + [pcm], headers, includes, modules + [cur_module], features, toolchain, module_srcs = ctx.files.interface)
     obj_files = depset(cpp_strip_objects(obj_files, features, toolchain), transitive = collect_module_objects(ctx.attr.deps + ctx.attr.partitions))
 
     return CppModuleInfo(

integration_tests/rules/BUILD.bazel

@@ -9,6 +9,7 @@ load(
 
 cpp_module(
     name = "test",
+    srcs = ["module/impl.cpp"],
     interface = "module/interface.cppm",
     module_name = "test",
 )

integration_tests/rules/module/impl.cpp

@@ -0,0 +1,7 @@
+module;
+
+#include <iostream>
+
+module test;
+
+void hello_impl() { std::cout << "hello impl\n"; }

integration_tests/rules/module/interface.cppm

@@ -4,6 +4,6 @@ module;
 
 export module test;
 
-export void hello() {
-    std::cout << "Hello from module\n";
-}
+export void hello() { std::cout << "Hello from module\n"; }
+
+export void hello_impl();

integration_tests/rules/module/module_user.cpp

@@ -2,5 +2,6 @@ import test;
 
 int main() {
     hello();
+    hello_impl();
     return 0;
 }