Add an option to not build the private part of the Standard Library (swiftlang#40548)

This can be useful to reduce build times in certain configurations (e.g.
when we don't run tests).

Addresses rdar://86474460

Author: edymtt

stdlib/CMakeLists.txt

@@ -164,6 +164,10 @@ option(SWIFT_ENABLE_REFLECTION
   "Build stdlib with support for runtime reflection and mirrors."
   TRUE)
 
+option(SWIFT_STDLIB_BUILD_PRIVATE
+  "Build private part of the Standard Library."
+  TRUE)
+
 if(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME)
   set(SWIFT_CONCURRENCY_GLOBAL_EXECUTOR_default "singlethreaded")
 else()
@@ -329,5 +333,7 @@ swift_create_stdlib_targets("swift-test-stdlib" "" FALSE)
 # the clang resource directory symlink stops installing correctly.
 add_subdirectory(toolchain)
 add_subdirectory(public)
-add_subdirectory(private)
+if(SWIFT_STDLIB_BUILD_PRIVATE)
+  add_subdirectory(private)
+endif()
 add_subdirectory(tools)

utils/build-presets.ini

@@ -2582,10 +2582,12 @@ swift-freestanding-is-darwin=1
 swift-freestanding-triple-name=macosx11.0
 swift-freestanding-module-name=macos
 swift-freestanding-archs=x86_64
+build-swift-private-stdlib=0
 
 [preset: stdlib_S_standalone_darwin_x86_64,build,test]
 mixin-preset=stdlib_S_standalone_darwin_x86_64,build
 
+build-swift-private-stdlib=1
 test
 validation-test
 

utils/build_swift/build_swift/driver_arguments.py

@@ -1035,6 +1035,12 @@ def create_argument_parser():
     option('--build-external-benchmarks', toggle_true,
            help='skip building Swift Benchmark Suite')
 
+    option('--build-swift-private-stdlib', toggle_true,
+           default=True,
+           help='build the private part of the Standard Library. '
+                'This can be useful to reduce build times when e.g. '
+                'tests do not need to run')
+
     # -------------------------------------------------------------------------
     in_group('Skip testing specified targets')
 

utils/build_swift/tests/expected_options.py

@@ -84,6 +84,7 @@
     'build_swift_dynamic_sdk_overlay': True,
     'build_swift_dynamic_stdlib': True,
     'build_swift_inspect': False,
+    'build_swift_private_stdlib': True,
     'build_swift_static_sdk_overlay': False,
     'build_swift_static_stdlib': False,
     'build_swift_stdlib_unittest_extra': False,
@@ -539,6 +540,7 @@ class BuildScriptImplOption(_BaseOption):
     EnableOption('--build-swift-static-stdlib'),
     EnableOption('--build-swift-stdlib-unittest-extra'),
     EnableOption('--build-swift-stdlib-static-print'),
+    EnableOption('--build-swift-private-stdlib'),
     EnableOption('--distcc'),
     EnableOption('--sccache'),
     EnableOption('--enable-asan'),

utils/swift_build_support/swift_build_support/products/swift.py

@@ -65,6 +65,8 @@ def __init__(self, args, toolchain, source_dir, build_dir):
         # Add freestanding related flags.
         self.cmake_options.extend(self._freestanding_is_darwin)
 
+        self.cmake_options.extend(self._build_swift_private_stdlib)
+
     @classmethod
     def is_build_script_impl_product(cls):
         """is_build_script_impl_product -> bool
@@ -179,6 +181,11 @@ def _freestanding_is_darwin(self):
         return [('SWIFT_FREESTANDING_IS_DARWIN:BOOL',
                  self.args.swift_freestanding_is_darwin)]
 
+    @property
+    def _build_swift_private_stdlib(self):
+        return [('SWIFT_STDLIB_BUILD_PRIVATE:BOOL',
+                 self.args.build_swift_private_stdlib)]
+
     @classmethod
     def get_dependencies(cls):
         return [cmark.CMark,

utils/swift_build_support/tests/products/test_swift.py

@@ -63,7 +63,8 @@ def setUp(self):
             enable_experimental_distributed=False,
             build_swift_stdlib_static_print=False,
             enable_experimental_string_processing=False,
-            swift_freestanding_is_darwin=False)
+            swift_freestanding_is_darwin=False,
+            build_swift_private_stdlib=True)
 
         # Setup shell
         shell.dry_run = True
@@ -100,6 +101,7 @@ def test_by_default_no_cmake_options(self):
             '-DSWIFT_STDLIB_STATIC_PRINT=FALSE',
             '-DSWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING:BOOL=FALSE',
             '-DSWIFT_FREESTANDING_IS_DARWIN:BOOL=FALSE',
+            '-DSWIFT_STDLIB_BUILD_PRIVATE:BOOL=TRUE',
         ]
         self.assertEqual(set(swift.cmake_options), set(expected))
 
@@ -121,6 +123,7 @@ def test_swift_runtime_tsan(self):
             '-DSWIFT_STDLIB_STATIC_PRINT=FALSE',
             '-DSWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING:BOOL=FALSE',
             '-DSWIFT_FREESTANDING_IS_DARWIN:BOOL=FALSE',
+            '-DSWIFT_STDLIB_BUILD_PRIVATE:BOOL=TRUE',
         ]
         self.assertEqual(set(swift.cmake_options), set(flags_set))
 
@@ -385,3 +388,16 @@ def test_freestanding_is_darwin_flags(self):
              'TRUE'],
             [x for x in swift.cmake_options
                 if 'SWIFT_FREESTANDING_IS_DARWIN' in x])
+
+    def test_build_swift_private_stdlib_flags(self):
+        self.args.build_swift_private_stdlib = False
+        swift = Swift(
+            args=self.args,
+            toolchain=self.toolchain,
+            source_dir='/path/to/src',
+            build_dir='/path/to/build')
+        self.assertEqual(
+            ['-DSWIFT_STDLIB_BUILD_PRIVATE:BOOL='
+             'FALSE'],
+            [x for x in swift.cmake_options
+                if 'SWIFT_STDLIB_BUILD_PRIVATE' in x])