[libc++] Move the long_tests Lit feature to the DSL

Author: ldionne

libcxx/utils/libcxx/test/config.py

@@ -74,7 +74,6 @@ def __init__(self, lit_config, config):
         self.use_target = False
         self.use_system_cxx_lib = self.get_lit_bool('use_system_cxx_lib', False)
         self.use_clang_verify = False
-        self.long_tests = None
 
     def get_lit_conf(self, name, default=None):
         val = self.lit_config.params.get(name, None)
@@ -285,18 +284,6 @@ def configure_features(self):
             self.config.available_features.add('availability=%s' % name)
             self.config.available_features.add('availability=%s%s' % (name, version))
 
-        # Simulator testing can take a really long time for some of these tests
-        # so add a feature check so we can REQUIRES: long_tests in them
-        self.long_tests = self.get_lit_bool('long_tests')
-        if self.long_tests is None:
-            # Default to running long tests.
-            self.long_tests = True
-            self.lit_config.note(
-                "inferred long_tests as: %r" % self.long_tests)
-
-        if self.long_tests:
-            self.config.available_features.add('long_tests')
-
         if self.target_info.is_windows():
             if self.cxx_stdlib_under_test == 'libc++':
                 # LIBCXX-WINDOWS-FIXME is the feature name used to XFAIL the

libcxx/utils/libcxx/test/params.py

@@ -33,4 +33,8 @@
             help="Whether to enable tests for the C++ <filesystem> library.",
             feature=lambda filesystem: None if filesystem else
               Feature(name='c++filesystem-disabled')),
+
+  Parameter(name='long_tests', choices=[True, False], type=bool, default=True,
+            help="Whether to tests that take longer to run. This can be useful when running on a very slow device.",
+            feature=lambda enabled: Feature(name='long_tests') if enabled else None),
 ]