Merge pull request #41436 from xedin/allow-specialization-from-default-expr

[TypeChecker] Allow inference from default expressions in certain scenarios (under a flag)

lib/Frontend/CompilerInvocation.cpp

@@ -1051,6 +1051,9 @@ static bool ParseTypeCheckerArgs(TypeCheckerOptions &Opts, ArgList &Args,
   Opts.EnableMultiStatementClosureInference |=
       Args.hasArg(OPT_experimental_multi_statement_closures);
 
+  Opts.EnableTypeInferenceFromDefaultArguments |=
+      Args.hasArg(OPT_experimental_type_inference_from_defaults);
+
   Opts.PrintFullConvention |=
       Args.hasArg(OPT_experimental_print_full_convention);