[build-script] Add an option to build the Foundation tests in another mode

Use it in the linux CI presets to set them to Debug mode and speed up the linux
CI, plus add a new preset which keeps building them in Release mode.

Author: finagolfin

utils/build-presets.ini

@@ -913,6 +913,7 @@ indexstore-db
 sourcekit-lsp
 swiftdocc
 lit-args=-v --time-tests
+foundation-tests-build-type=Debug
 
 # rdar://problem/31454823
 lldb-test-swift-only
@@ -935,6 +936,11 @@ mixin-preset=
 
 skip-test-swiftdocc
 
+[preset: buildbot_linux,release_foundation_tests]
+mixin-preset=buildbot_linux
+
+foundation-tests-build-type=Release
+
 [preset: buildbot_linux_crosscompile_wasm]
 mixin-preset=buildbot_linux
 
@@ -1095,6 +1101,7 @@ reconfigure
 test-optimized
 skip-test-swiftdocc
 lldb-test-swift-only
+foundation-tests-build-type=Debug
 
 # gcc version on amazon linux 2 is too old to configure and build tablegen.
 # Use the clang that we install in the path for macros
@@ -1203,6 +1210,7 @@ swiftsyntax
 swiftformat
 indexstore-db
 sourcekit-lsp
+foundation-tests-build-type=Debug
 
 install-llvm
 install-static-linux-config

utils/build_swift/build_swift/driver_arguments.py

@@ -94,6 +94,9 @@ def _apply_default_arguments(args):
     if args.foundation_build_variant is None:
         args.foundation_build_variant = args.build_variant
 
+    if args.foundation_tests_build_variant is None:
+        args.foundation_tests_build_variant = args.build_variant
+
     if args.libdispatch_build_variant is None:
         args.libdispatch_build_variant = args.build_variant
 
@@ -955,6 +958,12 @@ def create_argument_parser():
            const='Debug',
            help='build the Debug variant of Foundation')
 
+    option('--foundation-tests-build-type', store('foundation_tests_build_variant'),
+           choices=['Debug', 'Release'],
+           default=None,
+           help='build the Foundation tests in a certain variant '
+                '(Debug builds much faster)')
+
     option('--debug-libdispatch', store('libdispatch_build_variant'),
            const='Debug',
            help='build the Debug variant of libdispatch')

utils/build_swift/tests/build_swift/test_driver_arguments.py

@@ -542,6 +542,7 @@ def test_implied_defaults_build_variant(self):
 
         self.assertEqual(namespace.cmark_build_variant, 'Debug')
         self.assertEqual(namespace.foundation_build_variant, 'Debug')
+        self.assertEqual(namespace.foundation_tests_build_variant, 'Debug')
         self.assertEqual(namespace.libdispatch_build_variant, 'Debug')
         self.assertEqual(namespace.lldb_build_variant, 'Debug')
         self.assertEqual(namespace.llvm_build_variant, 'Debug')

utils/build_swift/tests/expected_options.py

@@ -201,6 +201,7 @@
     'swift_debuginfo_non_lto_args': None,
     'force_optimized_typechecker': False,
     'foundation_build_variant': 'Debug',
+    'foundation_tests_build_variant': 'Debug',
     'host_cc': None,
     'host_cxx': None,
     'host_libtool': None,
@@ -783,6 +784,8 @@ class BuildScriptImplOption(_BaseOption):
                   choices=['false', 'not-merged', 'merged']),
     ChoicesOption('--android-arch',
                   choices=['armv7', 'aarch64', 'x86_64']),
+    ChoicesOption('--foundation-tests-build-type',
+                  dest='foundation_tests_build_variant', choices=['Debug', 'Release']),
 
     StrOption('--android-api-level'),
     StrOption('--build-args'),

utils/swift_build_support/swift_build_support/products/foundationtests.py

@@ -53,7 +53,10 @@ def should_test(self, host_target):
         return self.args.test_foundation
 
     def configuration(self):
-        return 'release' if self.is_release() else 'debug'
+        if self.args.foundation_tests_build_variant in ['Release', 'RelWithDebInfo']:
+            return 'release'
+        else:
+            return 'debug'
 
     def test(self, host_target):
         swift_exec = os.path.join(

utils/swift_build_support/swift_build_support/products/swiftfoundationtests.py

@@ -53,7 +53,10 @@ def should_test(self, host_target):
         return self.args.test_foundation
 
     def configuration(self):
-        return 'release' if self.is_release() else 'debug'
+        if self.args.foundation_tests_build_variant in ['Release', 'RelWithDebInfo']:
+            return 'release'
+        else:
+            return 'debug'
 
     def test(self, host_target):
         swift_exec = os.path.join(