Frontend: Add -enable-parametrized-protocol-types flag

Author: slavapestov

include/swift/Basic/LangOptions.h

@@ -317,6 +317,10 @@ namespace swift {
     /// keyword.
     bool EnableExplicitExistentialTypes = true;
 
+    /// Enable support for protocol types parametrized by primary
+    /// associated type.
+    bool EnableParametrizedProtocolTypes = false;
+
     /// Enable experimental flow-sensitive concurrent captures.
     bool EnableExperimentalFlowSensitiveConcurrentCaptures = false;
 

include/swift/Option/FrontendOptions.td

@@ -506,6 +506,10 @@ def enable_explicit_existential_types :
   Flag<["-"], "enable-explicit-existential-types">,
   HelpText<"Enable experimental support for explicit existential types">;
 
+def enable_parametrized_protocol_types :
+  Flag<["-"], "enable-parametrized-protocol-types">,
+  HelpText<"Enable experimental support for primary associated types and parametrized protocols">;
+
 def enable_deserialization_recovery :
   Flag<["-"], "enable-deserialization-recovery">,
   HelpText<"Attempt to recover from missing xrefs (etc) in swiftmodules">;

lib/Frontend/CompilerInvocation.cpp

@@ -448,6 +448,9 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.EnableExplicitExistentialTypes |=
       Args.hasArg(OPT_enable_explicit_existential_types);
 
+  Opts.EnableParametrizedProtocolTypes |=
+      Args.hasArg(OPT_enable_parametrized_protocol_types);
+
   Opts.EnableExperimentalDistributed |=
     Args.hasArg(OPT_enable_experimental_distributed);