Update rules for ObjcProvider deprecations (#850)

In Bazel 7+ `ObjcProvider` no longer supports/provides the required
linking attributes.

The migrations is detailed here:
bazelbuild/bazel#16939. In summary, as part of
the migration, the `ObjcProvider` fields which previously provided
linking related information are now now longer providing that info. In
addition to this, a new flag:
`--incompatible_objc_linking_info_migration` was added to further delete
these link attrs from the `ObjcProvider` making it an error if the attr
is used or set.

The goal of this PR is to address support for `ObjcProvider` migration
and to instead use the correct linking information from `CcInfo`. This
will support both Bazel 6/7+. It does not try to support
`--incompatible_objc_linking_info_migration` as that requires more
changes and should be a separate PR

Depends on: 

- #848 
- #847

Author: luispadron

rules/force_load_direct_deps.bzl

@@ -1,36 +1,116 @@
+load("@bazel_skylib//lib:paths.bzl", "paths")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
 load("//rules:providers.bzl", "AvoidDepsInfo")
 load("//rules:transition_support.bzl", "transition_support")
 
-def _impl(ctx):
-    if not ctx.attr.should_force_load:
-        return apple_common.new_objc_provider()
+def _objc_provider_static_libraries(dep):
+    """Returns the ObjcProvider static libraries (.a) that should be force loaded.
+    """
+    if not apple_common.Objc in dep:
+        return []
+
+    return dep[apple_common.Objc].library.to_list()
+
+def _cc_info_static_libraries(dep):
+    """Returns the CcInfo static libraries (.a) that should be force loaded.
+
+    NOTE: CcInfo, unlike ObjcProvider, does not encode where the static library came from.
+    In the existing `_objc_provider_static_libraries` we only collect `.library` from ObjcProvider.
+    ObjcProvider `.library` list static library dependencies of the current target,
+    it does not include imported static libraries (such as those from `.framework` files).
+    CcInfo only provides `.static_library` and does not make this distinction.
+    To match this behavior, we only collect `.static_library` from CcInfo that are not from `.framework`s.
+    """
+    if not CcInfo in dep:
+        return []
+
+    static_cc_libraries = []
+    for linker_input in dep[CcInfo].linking_context.linker_inputs.to_list():
+        for library_to_link in linker_input.libraries:
+            if not library_to_link.static_library:
+                continue
+            containing_path = paths.dirname(library_to_link.static_library.path)
+            if containing_path.endswith(".framework"):
+                continue
+            static_cc_libraries.append(library_to_link.static_library)
 
-    force_load = []
+    return static_cc_libraries
 
+# TODO: We should deprecate this rule for Bazel 7+ as `--incompatible_objc_alwayslink_by_default` effectively
+#       does the same thing.
+def _force_load_direct_deps_impl(ctx):
+    """This rule will traverse the direct deps of the target and force load the static libraries of the objc deps.
+    """
+
+    if not ctx.attr.should_force_load:
+        return [
+            apple_common.new_objc_provider(),
+            CcInfo(),
+        ]
+
+    force_load_libraries = []
+    force_load_cc_libraries = []
     avoid_deps = []
+    avoid_libraries = {}
+    avoid_cc_libraries = {}
+    cc_toolchain = find_cpp_toolchain(ctx)
+    cc_features = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        language = "objc",
+    )
+
+    # Set the deps that should be avoided and not linked.
     for dep in ctx.attr.deps:
         if AvoidDepsInfo in dep:
             avoid_deps.extend(dep[AvoidDepsInfo].libraries)
 
-    avoid_libraries = {}
+    # Collect the libraries that should be avoided.
     for dep in avoid_deps:
-        if apple_common.Objc in dep:
-            for lib in dep[apple_common.Objc].library.to_list():
-                avoid_libraries[lib] = True
+        for lib in _objc_provider_static_libraries(dep):
+            avoid_libraries[lib] = True
+        for lib in _cc_info_static_libraries(dep):
+            avoid_cc_libraries[lib] = True
 
-    force_load = []
+    # Collect the libraries that should be force loaded.
     for dep in ctx.attr.deps:
-        if apple_common.Objc in dep:
-            for lib in dep[apple_common.Objc].library.to_list():
-                if not lib in avoid_libraries:
-                    force_load.append(lib)
-    return apple_common.new_objc_provider(
-        force_load_library = depset(force_load),
-        link_inputs = depset(force_load),
-    )
+        for lib in _objc_provider_static_libraries(dep):
+            if not lib in avoid_libraries:
+                force_load_libraries.append(lib)
+        for lib in _cc_info_static_libraries(dep):
+            if not lib in avoid_cc_libraries:
+                force_load_cc_libraries.append(lib)
+
+    return [
+        apple_common.new_objc_provider(
+            force_load_library = depset(force_load_libraries),
+            link_inputs = depset(force_load_libraries),
+        ),
+        CcInfo(
+            linking_context = cc_common.create_linking_context(
+                linker_inputs = depset([
+                    cc_common.create_linker_input(
+                        owner = ctx.label,
+                        libraries = depset([
+                            cc_common.create_library_to_link(
+                                actions = ctx.actions,
+                                cc_toolchain = cc_toolchain,
+                                feature_configuration = cc_features,
+                                static_library = library,
+                                alwayslink = True,
+                            )
+                            for library in force_load_cc_libraries
+                        ]),
+                    ),
+                ]),
+            ),
+        ),
+    ]
 
 force_load_direct_deps = rule(
-    implementation = _impl,
+    implementation = _force_load_direct_deps_impl,
+    toolchains = use_cpp_toolchain(),
+    fragments = ["apple", "cpp", "objc"],
     attrs = {
         "deps": attr.label_list(
             cfg = transition_support.apple_platform_split_transition,
@@ -58,6 +138,14 @@ force_load_direct_deps = rule(
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
             doc = "Needed to allow this rule to have an incoming edge configuration transition.",
         ),
+        "_cc_toolchain": attr.label(
+            providers = [cc_common.CcToolchainInfo],
+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+            doc = """\
+The C++ toolchain from which linking flags and other tools needed by the Swift
+toolchain (such as `clang`) will be retrieved.
+""",
+        ),
     },
     doc = """
 A rule to link with `-force_load` for direct`deps`

rules/framework.bzl

@@ -6,6 +6,7 @@ load("//rules:library.bzl", "PrivateHeadersInfo", "apple_library")
 load("//rules:plists.bzl", "process_infoplists")
 load("//rules:providers.bzl", "AvoidDepsInfo", "FrameworkInfo")
 load("//rules:transition_support.bzl", "transition_support")
+load("//rules:utils.bzl", "is_bazel_7")
 load("//rules/internal:objc_provider_utils.bzl", "objc_provider_utils")
 load("@bazel_skylib//lib:partial.bzl", "partial")
 load("@bazel_skylib//lib:paths.bzl", "paths")
@@ -534,6 +535,18 @@ def _get_symlinked_framework_clean_action(ctx, framework_files, compilation_cont
     else:
         ctx.actions.write(framework_manifest, "# Empty framework\n")
 
+def _get_cc_info_linker_inputs(*, deps):
+    linker_inputs = []
+
+    for dep in deps:
+        if not CcInfo in dep:
+            continue
+
+        for linker_input in dep[CcInfo].linking_context.linker_inputs.to_list():
+            linker_inputs.append(linker_input)
+
+    return depset(linker_inputs)
+
 def _create_swiftmodule(attrs):
     kwargs = {}
 
@@ -986,7 +999,9 @@ def _apple_framework_packaging_impl(ctx):
 
     split_slice_key = "{}_{}{}".format(platform, split_slice_varint, arch)
     deps = _attrs_for_split_slice(ctx.split_attr.deps, split_slice_key)
+    dep_cc_infos = [dep[CcInfo] for dep in deps if CcInfo in dep]
     transitive_deps = _attrs_for_split_slice(ctx.split_attr.transitive_deps, split_slice_key)
+    transitive_dep_cc_infos = [dep[CcInfo] for dep in transitive_deps if CcInfo in dep]
     vfs = _attrs_for_split_slice(ctx.split_attr.vfs, split_slice_key)
 
     current_apple_platform = transition_support.current_apple_platform(apple_fragment = ctx.fragments.apple, xcode_config = ctx.attr._xcode_config)
@@ -1004,15 +1019,15 @@ def _apple_framework_packaging_impl(ctx):
     ))
     objc_provider_utils.add_to_dict_if_present(compilation_context_fields, "defines", depset(
         direct = [],
-        transitive = [getattr(dep[CcInfo].compilation_context, "defines") for dep in deps if CcInfo in dep],
+        transitive = [getattr(cc_info.compilation_context, "defines") for cc_info in dep_cc_infos],
     ))
     objc_provider_utils.add_to_dict_if_present(compilation_context_fields, "includes", depset(
         direct = [],
-        transitive = [getattr(dep[CcInfo].compilation_context, "includes") for dep in deps if CcInfo in dep],
+        transitive = [getattr(cc_info.compilation_context, "includes") for cc_info in dep_cc_infos],
     ))
     objc_provider_utils.add_to_dict_if_present(compilation_context_fields, "framework_includes", depset(
         direct = [],
-        transitive = [getattr(dep[CcInfo].compilation_context, "framework_includes") for dep in deps if CcInfo in dep],
+        transitive = [getattr(cc_info.compilation_context, "framework_includes") for cc_info in dep_cc_infos],
     ))
 
     # Compute cc_info and swift_info
@@ -1031,17 +1046,23 @@ def _apple_framework_packaging_impl(ctx):
         # If not virtualizing the framework - then it runs a "clean"
         _get_symlinked_framework_clean_action(ctx, framework_files, compilation_context_fields)
 
+    # Construct the `CcInfo` provider, the linking context here used instead of ObjcProvider in Bazel 7+.
     cc_info_provider = CcInfo(
         compilation_context = cc_common.create_compilation_context(
             **compilation_context_fields
         ),
+        linking_context = cc_common.create_linking_context(
+            linker_inputs = _get_cc_info_linker_inputs(deps = deps) if is_bazel_7 else depset([]),
+        ),
     )
 
     if virtualize_frameworks:
         cc_info = cc_common.merge_cc_infos(direct_cc_infos = [cc_info_provider])
     else:
-        dep_cc_infos = [dep[CcInfo] for dep in transitive_deps if CcInfo in dep]
-        cc_info = cc_common.merge_cc_infos(direct_cc_infos = [cc_info_provider], cc_infos = dep_cc_infos)
+        cc_info = cc_common.merge_cc_infos(
+            direct_cc_infos = [cc_info_provider],
+            cc_infos = transitive_dep_cc_infos,
+        )
 
     # Propagate the avoid deps information upwards
     avoid_deps = []
@@ -1072,6 +1093,7 @@ def _apple_framework_packaging_impl(ctx):
         providers = [dep[apple_common.Objc] for dep in deps if apple_common.Objc in dep],
         transitive = [dep[apple_common.Objc] for dep in transitive_deps if apple_common.Objc in dep],
     )
+
     return [
         avoid_deps_info,
         framework_info,

rules/import_middleman.bzl

@@ -1,5 +1,4 @@
 load("@build_bazel_rules_apple//apple/internal:providers.bzl", "AppleFrameworkImportInfo", "new_appleframeworkimportinfo")
-load("//rules:features.bzl", "feature_names")
 load("//rules/internal:objc_provider_utils.bzl", "objc_provider_utils")
 load("@build_bazel_rules_apple//apple/internal:bundling_support.bzl", "bundling_support")
 
@@ -174,7 +173,6 @@ def _file_collector_rule_impl(ctx):
         # This should be correctly configured upstream: see setup in rules_ios
         fail("using import_middleman ({}) on wrong transition ({},{},is_device={})".format(ctx.attr.name, platform, arch, ctx.fragments.apple.single_arch_platform.is_device))
 
-    virtualize_frameworks = feature_names.virtualize_frameworks in ctx.features
     merge_keys = [
         "sdk_dylib",
         "sdk_framework",
@@ -184,17 +182,13 @@ def _file_collector_rule_impl(ctx):
         "link_inputs",
         "linkopt",
         "library",
-    ] + ([] if is_sim_arm64 else [
-        # Merge in the objc provider fields
-        "imported_library",
-        "dynamic_framework_file",
-        "static_framework_file",
-    ])
+    ]
 
     objc_provider_fields = objc_provider_utils.merge_objc_providers_dict(
         providers = [dep[apple_common.Objc] for dep in ctx.attr.deps],
         merge_keys = merge_keys,
     )
+
     exisiting_imported_libraries = objc_provider_fields.get("imported_library", depset([]))
     replaced_imported_libraries = _replace_inputs(ctx, exisiting_imported_libraries, input_imported_libraries, _update_lib).inputs
     objc_provider_fields["imported_library"] = depset(_deduplicate_test_deps(test_linker_deps[1], replaced_imported_libraries))
@@ -260,15 +254,15 @@ def _file_collector_rule_impl(ctx):
         **objc_provider_fields
     )
 
-    additional_providers = []
+    # Create the CcInfo provider, linking information from this is used in Bazel 7+.
     dep_cc_infos = [dep[CcInfo] for dep in ctx.attr.deps if CcInfo in dep]
-    cc_info = cc_common.merge_cc_infos(direct_cc_infos = [], cc_infos = dep_cc_infos)
-    additional_providers.append(cc_info)
+    cc_info = cc_common.merge_cc_infos(cc_infos = dep_cc_infos)
 
     return [
         DefaultInfo(files = depset(dynamic_framework_dirs + replaced_frameworks)),
         objc,
-    ] + _make_imports(dynamic_framework_dirs) + additional_providers
+        cc_info,
+    ] + _make_imports(dynamic_framework_dirs)
 
 import_middleman = rule(
     implementation = _file_collector_rule_impl,