Add support for emitting private swiftinterface (#1176)

luispadron · web-flow · commit 477df3a4576e · 2024-03-13T12:49:14.000-04:00
This PR adds a new feature: `swift.emit_private_swiftinterface` which
enables emitting `.private.swiftinterface` files for Swift modules.
These interface files are required when using `@_spi` and library
evolution.

## Example

```
bazel build //examples/apple/private_swiftinterface    
```

```
Target //examples/apple/private_swiftinterface:private_swiftinterface up-to-date:
  bazel-bin/examples/apple/private_swiftinterface/PrivateSwiftInterfaceLib.swiftdoc
  bazel-bin/examples/apple/private_swiftinterface/PrivateSwiftInterfaceLib.swiftinterface
  bazel-bin/examples/apple/private_swiftinterface/PrivateSwiftInterfaceLib.private.swiftinterface
  bazel-bin/examples/apple/private_swiftinterface/PrivateSwiftInterfaceLib.swiftmodule
  bazel-bin/examples/apple/private_swiftinterface/PrivateSwiftInterfaceLib.swiftsourceinfo
  bazel-bin/examples/apple/private_swiftinterface/libprivate_swiftinterface.a
```
diff --git a/doc/api.md b/doc/api.md
@@ -474,7 +474,8 @@ A provider whose type/layout is an implementation detail and should not
 
 <pre>
 swift_common.create_swift_module(<a href="#swift_common.create_swift_module-swiftdoc">swiftdoc</a>, <a href="#swift_common.create_swift_module-swiftmodule">swiftmodule</a>, <a href="#swift_common.create_swift_module-ast_files">ast_files</a>, <a href="#swift_common.create_swift_module-defines">defines</a>, <a href="#swift_common.create_swift_module-indexstore">indexstore</a>, <a href="#swift_common.create_swift_module-plugins">plugins</a>,
-                                 <a href="#swift_common.create_swift_module-swiftsourceinfo">swiftsourceinfo</a>, <a href="#swift_common.create_swift_module-swiftinterface">swiftinterface</a>, <a href="#swift_common.create_swift_module-symbol_graph">symbol_graph</a>)
+                                 <a href="#swift_common.create_swift_module-swiftsourceinfo">swiftsourceinfo</a>, <a href="#swift_common.create_swift_module-swiftinterface">swiftinterface</a>, <a href="#swift_common.create_swift_module-private_swiftinterface">private_swiftinterface</a>,
+                                 <a href="#swift_common.create_swift_module-symbol_graph">symbol_graph</a>)
 </pre>
 
 Creates a value representing a Swift module use as a Swift dependency.
@@ -492,6 +493,7 @@ Creates a value representing a Swift module use as a Swift dependency.
 | <a id="swift_common.create_swift_module-plugins"></a>plugins |  A list of `SwiftCompilerPluginInfo` providers representing compiler plugins that are required by this module and should be loaded by the compiler when this module is directly depended on.   |  `[]` |
 | <a id="swift_common.create_swift_module-swiftsourceinfo"></a>swiftsourceinfo |  The `.swiftsourceinfo` file emitted by the compiler for this module. May be `None` if no source info file was emitted.   |  `None` |
 | <a id="swift_common.create_swift_module-swiftinterface"></a>swiftinterface |  The `.swiftinterface` file emitted by the compiler for this module. May be `None` if no module interface file was emitted.   |  `None` |
+| <a id="swift_common.create_swift_module-private_swiftinterface"></a>private_swiftinterface |  The `.private.swiftinterface` file emitted by the compiler for this module. May be `None` if no private module interface file was emitted.   |  `None` |
 | <a id="swift_common.create_swift_module-symbol_graph"></a>symbol_graph |  A `File` representing the directory that contains the symbol graph data generated by the compiler if the `"swift.emit_symbol_graph"` feature is enabled, otherwise this will be `None`.   |  `None` |
 
 **RETURNS**
diff --git a/proto/swift_proto_library.bzl b/proto/swift_proto_library.bzl
@@ -185,6 +185,7 @@ def _swift_proto_library_impl(ctx):
             files = depset(compact([
                 module_context.swift.swiftdoc,
                 module_context.swift.swiftinterface,
+                module_context.swift.private_swiftinterface,
                 module_context.swift.swiftmodule,
                 module_context.swift.swiftsourceinfo,
                 linking_output.library_to_link.static_library,
@@ -266,7 +267,7 @@ from which the Swift protos will be generated.
                 ],
                 default = [],
                 doc = """\
-List of additional dependencies required by the generated Swift code at compile time, 
+List of additional dependencies required by the generated Swift code at compile time,
 whose SwiftProtoInfo will be ignored.
 """,
             ),
@@ -298,7 +299,7 @@ swift_proto_library(
 )
 ```
 
-If your protos depend on protos from other targets, add dependencies between the 
+If your protos depend on protos from other targets, add dependencies between the
 swift_proto_library targets which mirror the dependencies between the proto targets.
 
 ```python
diff --git a/swift/BUILD b/swift/BUILD
@@ -109,6 +109,12 @@ bool_setting(
     build_setting_default = False,
 )
 
+# Configuration setting for enabling the generation of private swiftinterface files (e.g. those for `@_spi`).
+bool_setting(
+    name = "emit_private_swiftinterface",
+    build_setting_default = False,
+)
+
 # NOTE: Enabling this flag will transition --proto_compiler to
 # //tools/protoc_wrapper:protoc for swift_grpc_library and swift_proto_library,
 # unless you set --proto_compiler manually.
diff --git a/swift/deprecated_proto/swift_protoc_gen_aspect.bzl b/swift/deprecated_proto/swift_protoc_gen_aspect.bzl
@@ -40,6 +40,7 @@ load(
 )
 load(
     "//swift/internal:feature_names.bzl",
+    "SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE",
     "SWIFT_FEATURE_EMIT_SWIFTINTERFACE",
     "SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION",
     "SWIFT_FEATURE_ENABLE_TESTING",
@@ -406,6 +407,10 @@ def _swift_protoc_gen_aspect_impl(target, aspect_ctx):
             extra_features.append(SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION)
             extra_features.append(SWIFT_FEATURE_EMIT_SWIFTINTERFACE)
 
+        if aspect_ctx.attr._config_emit_private_swiftinterface[BuildSettingInfo].value:
+            extra_features.append(SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION)
+            extra_features.append(SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE)
+
         # Compile the generated Swift sources and produce a static library and a
         # .swiftmodule as outputs. In addition to the other proto deps, we also
         # pass support libraries like the SwiftProtobuf runtime as deps to the
diff --git a/swift/internal/attrs.bzl b/swift/internal/attrs.bzl
@@ -169,8 +169,8 @@ support location expansion.
             "always_include_developer_search_paths": attr.bool(
                 default = False,
                 doc = """\
-If `True`, the developer framework search paths will be added to the compilation 
-command. This enables a Swift module to access `XCTest` without having to mark 
+If `True`, the developer framework search paths will be added to the compilation
+command. This enables a Swift module to access `XCTest` without having to mark
 the target as `testonly = True`.
 """,
                 mandatory = False,
@@ -186,6 +186,9 @@ def swift_config_attrs():
         configuration settings.
     """
     return {
+        "_config_emit_private_swiftinterface": attr.label(
+            default = "@build_bazel_rules_swift//swift:emit_private_swiftinterface",
+        ),
         "_config_emit_swiftinterface": attr.label(
             default = "@build_bazel_rules_swift//swift:emit_swiftinterface",
         ),
diff --git a/swift/internal/compiling.bzl b/swift/internal/compiling.bzl
@@ -47,6 +47,7 @@ load(
     "SWIFT_FEATURE_DISABLE_SYSTEM_INDEX",
     "SWIFT_FEATURE_EMIT_BC",
     "SWIFT_FEATURE_EMIT_C_MODULE",
+    "SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE",
     "SWIFT_FEATURE_EMIT_SWIFTINTERFACE",
     "SWIFT_FEATURE_EMIT_SYMBOL_GRAPH",
     "SWIFT_FEATURE_ENABLE_BATCH_MODE",
@@ -363,6 +364,17 @@ def compile_action_configs(
                 SWIFT_FEATURE_EMIT_SWIFTINTERFACE,
             ],
         ),
+        swift_toolchain_config.action_config(
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
+            configurators = [_emit_private_module_interface_path_configurator],
+            features = [
+                SWIFT_FEATURE_SUPPORTS_LIBRARY_EVOLUTION,
+                SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE,
+            ],
+        ),
 
         # Configure the path to the emitted *-Swift.h file.
         swift_toolchain_config.action_config(
@@ -1351,6 +1363,10 @@ def _emit_module_interface_path_configurator(prerequisites, args):
     """Adds the `.swiftinterface` output path to the command line."""
     args.add("-emit-module-interface-path", prerequisites.swiftinterface_file)
 
+def _emit_private_module_interface_path_configurator(prerequisites, args):
+    """Adds the `.private.swiftinterface` output path to the command line."""
+    args.add("-emit-private-module-interface-path", prerequisites.private_swiftinterface_file)
+
 def _emit_objc_header_path_configurator(prerequisites, args):
     """Adds the generated header output path to the command line."""
     if prerequisites.generated_header_file:
@@ -2375,6 +2391,7 @@ def compile(
     if split_derived_file_generation:
         all_compile_outputs = compact([
             compile_outputs.swiftinterface_file,
+            compile_outputs.private_swiftinterface_file,
             compile_outputs.indexstore_directory,
             compile_outputs.macro_expansion_directory,
         ]) + compile_outputs.object_files
@@ -2398,6 +2415,7 @@ def compile(
             compile_outputs.swiftmodule_file,
             compile_outputs.swiftdoc_file,
             compile_outputs.swiftinterface_file,
+            compile_outputs.private_swiftinterface_file,
             compile_outputs.swiftsourceinfo_file,
             compile_outputs.generated_header_file,
             compile_outputs.indexstore_directory,
@@ -2628,6 +2646,7 @@ to use swift_common.compile(include_dev_srch_paths = ...) instead.\
             defines = defines,
             indexstore = compile_outputs.indexstore_directory,
             plugins = depset(plugins),
+            private_swiftinterface = compile_outputs.private_swiftinterface_file,
             swiftdoc = compile_outputs.swiftdoc_file,
             swiftinterface = compile_outputs.swiftinterface_file,
             swiftmodule = compile_outputs.swiftmodule_file,
@@ -2964,6 +2983,20 @@ def _declare_compile_outputs(
     else:
         swiftinterface_file = None
 
+    if are_all_features_enabled(
+        feature_configuration = feature_configuration,
+        feature_names = [
+            SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION,
+            SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE,
+        ],
+    ):
+        private_swiftinterface_file = derived_files.private_swiftinterface(
+            actions = actions,
+            module_name = module_name,
+        )
+    else:
+        private_swiftinterface_file = None
+
     # If requested, generate the Swift header for this library so that it can be
     # included by Objective-C code that depends on it.
     if generated_header_name:
@@ -3110,6 +3143,7 @@ def _declare_compile_outputs(
         generated_module_map_file = generated_module_map,
         indexstore_directory = indexstore_directory,
         macro_expansion_directory = macro_expansion_directory,
+        private_swiftinterface_file = private_swiftinterface_file,
         symbol_graph_directory = symbol_graph_directory,
         object_files = object_files,
         output_file_map = output_file_map,
diff --git a/swift/internal/derived_files.bzl b/swift/internal/derived_files.bzl
@@ -266,6 +266,18 @@ def _swiftinterface(actions, module_name):
     """
     return actions.declare_file("{}.swiftinterface".format(module_name))
 
+def _private_swiftinterface(actions, module_name):
+    """Declares a file for the private Swift interface created by a compilation rule.
+
+    Args:
+        actions: The context's actions object.
+        module_name: The name of the module being built.
+
+    Returns:
+        The declared `File`.
+    """
+    return actions.declare_file("{}.private.swiftinterface".format(module_name))
+
 def _swiftmodule(actions, module_name):
     """Declares a file for the Swift module created by a compilation rule.
 
@@ -344,6 +356,7 @@ derived_files = struct(
     module_map = _module_map,
     modulewrap_object = _modulewrap_object,
     precompiled_module = _precompiled_module,
+    private_swiftinterface = _private_swiftinterface,
     reexport_modules_src = _reexport_modules_src,
     static_archive = _static_archive,
     swiftc_output_file_map = _swiftc_output_file_map,
diff --git a/swift/internal/feature_names.bzl b/swift/internal/feature_names.bzl
@@ -253,6 +253,10 @@ SWIFT_FEATURE_EMIT_BC = "swift.emit_bc"
 # invocation.
 SWIFT_FEATURE_EMIT_SWIFTINTERFACE = "swift.emit_swiftinterface"
 
+# If enabled, requests the private swiftinterface file to be built on the
+# swiftc invocation.
+SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE = "swift.emit_private_swiftinterface"
+
 # If enabled, the toolchain supports private deps (implementation-only imports).
 # This allows Bazel to avoid propagating swiftmodules of such dependencies
 # higher in the dependency graph than they need to be.
diff --git a/swift/internal/providers.bzl b/swift/internal/providers.bzl
@@ -141,7 +141,7 @@ Returns:
 """,
         "compiler_deps": """\
 List of targets providing SwiftInfo and CcInfo.
-These are added as dependencies to the swift compile action of the swift_proto_library. 
+These are added as dependencies to the swift compile action of the swift_proto_library.
 Typically these are proto runtime libraries.
 
 Well Known Types should be added as dependencies of the swift_proto_library
@@ -166,12 +166,12 @@ files to Swift modules. This allows messages that reference messages in other
 libraries to import those modules in generated code.
 """,
         "direct_pbswift_files": """\
-`list` of `File`s. The Swift source files (e.g. `.pb.swift`) generated from the 
+`list` of `File`s. The Swift source files (e.g. `.pb.swift`) generated from the
 `ProtoInfo` providers of the direct proto dependencies of the `swift_proto_library` target.
 """,
         "pbswift_files": """\
-`depset` of `File`s. The Swift source files (e.g. `.pb.swift`) generated from the 
-`ProtoInfo` providers of the direct and transitive transitive proto dependencies 
+`depset` of `File`s. The Swift source files (e.g. `.pb.swift`) generated from the
+`ProtoInfo` providers of the direct and transitive transitive proto dependencies
 of the `swift_proto_library` target.
 """,
     },
@@ -447,6 +447,7 @@ def create_swift_module(
         plugins = [],
         swiftsourceinfo = None,
         swiftinterface = None,
+        private_swiftinterface = None,
         symbol_graph = None):
     """Creates a value representing a Swift module use as a Swift dependency.
 
@@ -464,6 +465,9 @@ def create_swift_module(
         plugins: A list of `SwiftCompilerPluginInfo` providers representing
             compiler plugins that are required by this module and should be
             loaded by the compiler when this module is directly depended on.
+        private_swiftinterface: The `.private.swiftinterface` file emitted by
+            the compiler for this module. May be `None` if no private module
+            interface file was emitted.
         swiftsourceinfo: The `.swiftsourceinfo` file emitted by the compiler for
             this module. May be `None` if no source info file was emitted.
         swiftinterface: The `.swiftinterface` file emitted by the compiler for
@@ -482,6 +486,7 @@ def create_swift_module(
         ast_files = tuple(ast_files),
         defines = tuple(defines),
         plugins = plugins,
+        private_swiftinterface = private_swiftinterface,
         indexstore = indexstore,
         swiftdoc = swiftdoc,
         swiftinterface = swiftinterface,
diff --git a/swift/internal/swift_library.bzl b/swift/internal/swift_library.bzl
@@ -30,6 +30,7 @@ load(
 )
 load(
     ":feature_names.bzl",
+    "SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE",
     "SWIFT_FEATURE_EMIT_SWIFTINTERFACE",
     "SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION",
     "SWIFT_FEATURE_SUPPORTS_PRIVATE_DEPS",
@@ -124,6 +125,10 @@ def _swift_library_impl(ctx):
         extra_features.append(SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION)
         extra_features.append(SWIFT_FEATURE_EMIT_SWIFTINTERFACE)
 
+    if ctx.attr._config_emit_private_swiftinterface[BuildSettingInfo].value:
+        extra_features.append(SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION)
+        extra_features.append(SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE)
+
     module_name = ctx.attr.module_name
     if not module_name:
         module_name = swift_common.derive_module_name(ctx.label)
@@ -228,6 +233,7 @@ def _swift_library_impl(ctx):
         module_context.clang.precompiled_module,
         module_context.swift.swiftdoc,
         module_context.swift.swiftinterface,
+        module_context.swift.private_swiftinterface,
         module_context.swift.swiftmodule,
         module_context.swift.swiftsourceinfo,
         linking_output.library_to_link.static_library,
diff --git a/swift/internal/swift_module_alias.bzl b/swift/internal/swift_module_alias.bzl
@@ -91,6 +91,7 @@ def _swift_module_alias_impl(ctx):
             files = depset(compact([
                 module_context.swift.swiftdoc,
                 module_context.swift.swiftinterface,
+                module_context.swift.private_swiftinterface,
                 module_context.swift.swiftmodule,
                 linking_output.library_to_link.pic_static_library,
                 linking_output.library_to_link.static_library,
diff --git a/test/BUILD b/test/BUILD
@@ -14,6 +14,7 @@ load(":module_interface_tests.bzl", "module_interface_test_suite")
 load(":output_file_map_tests.bzl", "output_file_map_test_suite")
 load(":pch_output_dir_tests.bzl", "pch_output_dir_test_suite")
 load(":private_deps_tests.bzl", "private_deps_test_suite")
+load(":private_swiftinterface_tests.bzl", "private_swiftinterface_test_suite")
 load(":split_derived_files_tests.bzl", "split_derived_files_test_suite")
 load(":swift_through_non_swift_tests.bzl", "swift_through_non_swift_test_suite")
 load(":utils_tests.bzl", "utils_test_suite")
@@ -51,6 +52,8 @@ split_derived_files_test_suite(name = "split_derived_files")
 
 pch_output_dir_test_suite(name = "pch_output_dir_settings")
 
+private_swiftinterface_test_suite(name = "private_swiftinterface")
+
 explicit_modules_test_suite(name = "explicit_modules")
 
 xctest_runner_test_suite(name = "xctest_runner")
diff --git a/test/fixtures/private_swiftinterface/BUILD b/test/fixtures/private_swiftinterface/BUILD
diff --git a/test/fixtures/private_swiftinterface/Lib.swift b/test/fixtures/private_swiftinterface/Lib.swift
diff --git a/test/fixtures/private_swiftinterface/main.swift b/test/fixtures/private_swiftinterface/main.swift
diff --git a/test/private_swiftinterface_tests.bzl b/test/private_swiftinterface_tests.bzl
diff --git a/test/rules/swift_library_artifact_collector.bzl b/test/rules/swift_library_artifact_collector.bzl
