Add Escapable conformance to some builtin functions

Author: meg-gupta

lib/AST/Builtins.cpp

@@ -2102,12 +2102,17 @@ static ValueDecl *getOnceOperation(ASTContext &Context,
   return getBuiltinFunction(Id, ArgTypes, Context.TheSILTokenType);
 }
 
+
 static ValueDecl *getPolymorphicBinaryOperation(ASTContext &ctx,
                                                 Identifier id) {
   BuiltinFunctionBuilder builder(ctx);
-  builder.addParameter(makeGenericParam());
-  builder.addParameter(makeGenericParam());
-  builder.setResult(makeGenericParam());
+
+  // Builtins of the form: func binOp<T>(_ t: T, _ t: T) -> T
+  auto genericParam = makeGenericParam();
+  builder.addConformanceRequirement(genericParam, KnownProtocolKind::Escapable);
+  builder.addParameter(genericParam);
+  builder.addParameter(genericParam);
+  builder.setResult(genericParam);
   return builder.build(id);
 }
 

lib/AST/ConformanceLookup.cpp

@@ -839,6 +839,10 @@ static bool conformsToInvertible(CanType type, InvertibleProtocolKind ip) {
   if (type->is<SILPackType>())
     return true;
 
+  if (type->is<SILTokenType>()) {
+    return true;
+  }
+
   // The SIL types in the AST do not have real conformances, and should have
   // been handled in SILType instead.
   assert(!(type->is<SILBoxType,