Move link-related info out of SwiftInfo and into CcInfo.

As of this change, all Swift targets propagate a `CcInfo` provider that references the libraries that dependents should link in order to use that library. The `SwiftInfo` provided by the library now only contains Swift-specific information, such as the `.swiftmodule` files that dependents need.

RELNOTES: The `direct_libraries`, `direct_linkopts`, `transitive_additional_inputs`, `transitive_libraries`, and `transitive_linkopts` fields of `SwiftInfo` have been removed. This information is now propagated using linking contexts in `CcInfo` providers.

RELNOTES: `swift_grpc_library` and `swift_proto_library` now return the generated source files as default outputs for easier inspection.
PiperOrigin-RevId: 246581943

Author: allevato

swift/internal/api.bzl

@@ -74,54 +74,58 @@ _SANITIZER_FEATURE_FLAG_MAP = {
 }
 
 def _create_swift_info(
-        additional_inputs = [],
         defines = [],
-        libraries = [],
-        linkopts = [],
         module_name = None,
         swiftdocs = [],
         swiftmodules = [],
+        swift_infos = [],
         swift_version = None):
     """Creates a new `SwiftInfo` provider with the given values.
 
     This function is recommended instead of directly creating a `SwiftInfo` provider because it
     encodes reasonable defaults for fields that some rules may not be interested in and ensures
     that the direct and transitive fields are set consistently.
 
+    This function can also be used to do a simple merge of `SwiftInfo` providers, by leaving all
+    of the arguments except for `swift_infos` as their empty defaults. In that case, the returned
+    provider will not represent a true Swift module; it is merely a "collector" for other
+    dependencies.
+
     Args:
-        additional_inputs: A list of additional input files passed into a library or binary target
-            via the `swiftc_inputs` attribute.
         defines: A list of defines that will be provided as `copts` of the target being built.
-        libraries: A list of `.a` files that are the direct outputs of the target being built.
-        linkopts: A list of linker flags that will be passed to the linker when the target being
-            built is linked into a binary.
-        module_name: A string containing the name of the Swift module, or `None` if the provider
-            does not represent a compiled module (this happens, for example, with `proto_library`
-            targets that act as "collectors" of other modules but have no sources of their own).
+        module_name: A string containing the name of the Swift module. If this is `None`, the
+            provider does not represent a compiled module but rather a collection of modules (this
+            happens, for example, with `proto_library` targets that have no sources of their own
+            but depend on others that do).
         swiftdocs: A list of `.swiftdoc` files that are the direct outputs of the target being
-            built.
+            built. If omitted, an empty list is used.
         swiftmodules: A list of `.swiftmodule` files that are the direct outputs of the target
-            being built.
+            being built. If omitted, an empty list is used.
+        swift_infos: A list of `SwiftInfo` providers from dependencies, whose transitive fields
+            should be merged into the new one. If omitted, no transitive data is collected.
         swift_version: A string containing the value of the `-swift-version` flag used when
-            compiling this target, or `None` if it was not set or is not relevant.
+            compiling this target, or `None` (the default) if it was not set or is not relevant.
 
     Returns:
         A new `SwiftInfo` provider with the given values.
     """
+    transitive_defines = []
+    transitive_swiftdocs = []
+    transitive_swiftmodules = []
+    for swift_info in swift_infos:
+        transitive_defines.append(swift_info.transitive_defines)
+        transitive_swiftdocs.append(swift_info.transitive_swiftdocs)
+        transitive_swiftmodules.append(swift_info.transitive_swiftmodules)
+
     return SwiftInfo(
         direct_defines = defines,
-        direct_libraries = libraries,
-        direct_linkopts = linkopts,
         direct_swiftdocs = swiftdocs,
         direct_swiftmodules = swiftmodules,
         module_name = module_name,
         swift_version = swift_version,
-        transitive_additional_inputs = depset(direct = additional_inputs),
-        transitive_defines = depset(direct = defines),
-        transitive_libraries = depset(direct = libraries, order = "topological"),
-        transitive_linkopts = depset(direct = linkopts),
-        transitive_swiftdocs = depset(direct = swiftdocs),
-        transitive_swiftmodules = depset(direct = swiftmodules),
+        transitive_defines = depset(defines, transitive = transitive_defines),
+        transitive_swiftdocs = depset(swiftdocs, transitive = transitive_swiftdocs),
+        transitive_swiftmodules = depset(swiftmodules, transitive = transitive_swiftmodules),
     )
 
 def _compilation_attrs(additional_deps_aspects = []):
@@ -831,46 +835,6 @@ conformance.
         },
     )
 
-def _merge_swift_infos(swift_infos):
-    """Merges a list of `SwiftInfo` providers into one.
-
-    Args:
-        swift_infos: A sequence of `SwiftInfo`providers to merge.
-
-    Returns:
-        A new `SwiftInfo` provider.
-    """
-    transitive_additional_inputs = []
-    transitive_defines = []
-    transitive_libraries = []
-    transitive_linkopts = []
-    transitive_swiftdocs = []
-    transitive_swiftmodules = []
-
-    for swift_info in swift_infos:
-        transitive_additional_inputs.append(swift_info.transitive_additional_inputs)
-        transitive_defines.append(swift_info.transitive_defines)
-        transitive_libraries.append(swift_info.transitive_libraries)
-        transitive_linkopts.append(swift_info.transitive_linkopts)
-        transitive_swiftdocs.append(swift_info.transitive_swiftdocs)
-        transitive_swiftmodules.append(swift_info.transitive_swiftmodules)
-
-    return SwiftInfo(
-        direct_defines = [],
-        direct_libraries = [],
-        direct_linkopts = [],
-        direct_swiftdocs = [],
-        direct_swiftmodules = [],
-        module_name = None,
-        swift_version = None,
-        transitive_additional_inputs = depset(transitive = transitive_additional_inputs),
-        transitive_defines = depset(transitive = transitive_defines),
-        transitive_libraries = depset(transitive = transitive_libraries),
-        transitive_linkopts = depset(transitive = transitive_linkopts),
-        transitive_swiftdocs = depset(transitive = transitive_swiftdocs),
-        transitive_swiftmodules = depset(transitive = transitive_swiftmodules),
-    )
-
 def _swift_runtime_linkopts(is_static, toolchain, is_test = False):
     """Returns the flags that should be passed to `clang` when linking a binary.
 
@@ -1064,7 +1028,6 @@ swift_common = struct(
     derive_module_name = _derive_module_name,
     is_enabled = _is_enabled,
     library_rule_attrs = _library_rule_attrs,
-    merge_swift_infos = _merge_swift_infos,
     run_toolchain_action = run_toolchain_action,
     run_toolchain_shell_action = run_toolchain_shell_action,
     run_toolchain_swift_action = run_toolchain_swift_action,

swift/internal/attrs.bzl

@@ -15,7 +15,6 @@
 """Common attributes used by multiple Swift build rules."""
 
 load(":providers.bzl", "SwiftClangModuleInfo", "SwiftInfo")
-load(":swift_cc_libs_aspect.bzl", "swift_cc_libs_aspect")
 
 def swift_common_rule_attrs(additional_deps_aspects = []):
     return {
@@ -30,7 +29,7 @@ binary or library, or other programs needed by it.
 """,
         ),
         "deps": attr.label_list(
-            aspects = [swift_cc_libs_aspect] + additional_deps_aspects,
+            aspects = additional_deps_aspects,
             doc = """
 A list of targets that are dependencies of the target being built, which will be
 linked into that target. Allowed kinds of dependencies are:

swift/internal/compiling.bzl

@@ -22,13 +22,14 @@ load(
 )
 load(":actions.bzl", "run_toolchain_swift_action")
 load(":derived_files.bzl", "derived_files")
+load(":providers.bzl", "SwiftClangModuleInfo", "SwiftInfo")
 load(
-    ":providers.bzl",
-    "SwiftCcLibsInfo",
-    "SwiftClangModuleInfo",
-    "SwiftInfo",
+    ":utils.bzl",
+    "collect_cc_libraries",
+    "collect_transitive",
+    "get_providers",
+    "objc_provider_framework_name",
 )
-load(":utils.bzl", "collect_transitive", "objc_provider_framework_name")
 
 # Swift compiler options that cause the code to be compiled using whole-module optimization.
 _WMO_COPTS = ("-force-single-frontend-invocation", "-whole-module-optimization", "-wmo")
@@ -276,25 +277,25 @@ def new_objc_provider(
     Returns:
         An `apple_common.Objc` provider that should be returned by the calling rule.
     """
-    objc_providers = [dep[apple_common.Objc] for dep in deps if apple_common.Objc in dep]
+    objc_providers = get_providers(deps, apple_common.Objc)
     objc_provider_args = {
-        "library": depset(direct = static_archives),
         "link_inputs": depset(direct = swiftmodules + link_inputs),
         "providers": objc_providers,
         "uses_swift": True,
     }
 
-    # Collect static libraries that came from cc_library targets, and include them in the
-    # Objective-C provider. This ensures that they get linked into apple_binaries, which otherwise
-    # wouldn't be able to see them.
+    # The link action registered by `apple_binary` only looks at `Objc` providers, not `CcInfo`,
+    # for libraries to link. Until that rule is migrated over, we need to collect libraries from
+    # `CcInfo` (which will include Swift and C++) and put them into the new `Objc` provider.
     transitive_cc_libs = []
-    for dep in deps:
-        if SwiftCcLibsInfo in dep:
-            cc_libraries = dep[SwiftCcLibsInfo].libraries
-            if cc_libraries:
-                transitive_cc_libs.append(cc_libraries)
-    if transitive_cc_libs:
-        objc_provider_args["imported_library"] = depset(transitive = transitive_cc_libs)
+    for cc_info in get_providers(deps, CcInfo):
+        static_libs = collect_cc_libraries(cc_info = cc_info, include_static = True)
+        transitive_cc_libs.append(depset(static_libs, order = "topological"))
+    objc_provider_args["library"] = depset(
+        static_archives,
+        transitive = transitive_cc_libs,
+        order = "topological",
+    )
 
     if include_path:
         objc_provider_args["include"] = depset(direct = [include_path])
@@ -343,7 +344,7 @@ def objc_compile_requirements(args, deps):
     static_framework_names = []
     all_frameworks = []
 
-    objc_providers = [dep[apple_common.Objc] for dep in deps if apple_common.Objc in dep]
+    objc_providers = get_providers(deps, apple_common.Objc)
 
     post_framework_cleanup = framework_migration.is_post_framework_migration()