Fix another edge case in compile planning; this time if -c opt is used and -wmo is passed on the command line.

Cherry-pick: 66a6a6b

Author: luispadron

swift/internal/compiling.bzl

@@ -802,6 +802,9 @@ def _should_plan_parallel_compilation(
         ) or are_all_features_enabled(
             feature_configuration = feature_configuration,
             feature_names = [SWIFT_FEATURE_OPT, SWIFT_FEATURE_OPT_USES_WMO],
+        ) or is_feature_enabled(
+            feature_configuration = feature_configuration,
+            feature_name = SWIFT_FEATURE__WMO_IN_SWIFTCOPTS,
         )
     ):
         return True

test/parallel_compilation_tests.bzl

@@ -35,6 +35,15 @@ opt_via_swiftcopt_actions_create_test = make_actions_created_test_rule(
     },
 )
 
+opt_with_wmo_via_swiftcopt_actions_create_test = make_actions_created_test_rule(
+    config_settings = {
+        "//command_line_option:compilation_mode": "opt",
+        str(Label("//swift:copt")): [
+            "-whole-module-optimization",
+        ],
+    },
+)
+
 def parallel_compilation_test_suite(name, tags = []):
     """Test suite for parallel compilation.
 
@@ -120,6 +129,15 @@ def parallel_compilation_test_suite(name, tags = []):
         target_under_test = "//test/fixtures/parallel_compilation:onone_with_wmo",
     )
 
+    # Optimized (via `-c opt`) with-WMO cannot be compiled in parallel if CMO is
+    # enabled (the default).
+    opt_with_wmo_via_swiftcopt_actions_create_test(
+        name = "{}_with_opt_via_compilation_mode_opt_with_wmo".format(name),
+        mnemonics = ["-SwiftCompileModule", "-SwiftCompileCodegen", "SwiftCompile"],
+        tags = all_tags,
+        target_under_test = "//test/fixtures/parallel_compilation:no_opt_no_wmo",
+    )
+
     # The analysis tests verify that we register the actions we expect. Use a
     # `build_test` to make sure the actions execute successfully.
     build_test(