Merge pull request #35715 from mikeash/protocol-conformance-shared-cache

[Runtime] Support precomputed protocol conformances in the shared cache.

Author: mikeash

stdlib/public/runtime/EnvironmentVariables.def

@@ -47,4 +47,12 @@ VARIABLE(SWIFT_DEBUG_ENABLE_MALLOC_SCRIBBLE, bool, false,
 VARIABLE(SWIFT_DEBUG_ENABLE_COW_CHECKS, bool, false,
          "Enable internal checks for copy-on-write operations.")
 
+#if defined(__APPLE__) && defined(__MACH__)
+
+VARIABLE(SWIFT_DEBUG_VALIDATE_SHARED_CACHE_PROTOCOL_CONFORMANCES, bool, false,
+         "Validate shared cache protocol conformance results against the "
+         "lists of conformances in the shared cache images.")
+
+#endif
+
 #undef VARIABLE