[Frontend] Move generic sig verification to end of pipeline

Author: hamishknight

lib/FrontendTool/FrontendTool.cpp

@@ -1247,6 +1247,9 @@ static void performEndOfPipelineActions(CompilerInstance &Instance) {
   // Verify the AST for all the modules we've loaded.
   ctx.verifyAllLoadedModules();
 
+  // Verify generic signatures if we've been asked to.
+  verifyGenericSignaturesIfNeeded(Invocation, ctx);
+
   // Emit dependencies and index data.
   emitReferenceDependenciesForAllPrimaryInputsIfNeeded(Instance);
   emitIndexData(Instance);
@@ -1345,8 +1348,6 @@ static bool performCompile(CompilerInstance &Instance,
       debugFailWithCrash();
   }
 
-  verifyGenericSignaturesIfNeeded(Invocation, Context);
-
   (void)migrator::updateCodeAndEmitRemapIfNeeded(&Instance);
 
   if (Action == FrontendOptions::ActionType::REPL) {