Merge pull request #6306 from hughbe/silgen-msvc-fixes

Fix MSVC errors compiling GenericSignature.h

Author: compnerd

include/swift/AST/GenericSignature.h

@@ -128,11 +128,10 @@ class alignas(1 << TypeAlignInBits) GenericSignature final
   void getSubstitutionMap(ArrayRef<Substitution> args,
                           SubstitutionMap &subMap) const;
 
-  using LookupConformanceFn =
-      llvm::function_ref<auto(CanType dependentType,
-                              Type conformingReplacementType,
-                              ProtocolType *conformedProtocol)
-                         -> Optional<ProtocolConformanceRef>>;
+  using GenericFunction = auto(CanType canType, Type conformingReplacementType,
+    ProtocolType *conformedProtocol)
+    ->Optional<ProtocolConformanceRef>;
+  using LookupConformanceFn = llvm::function_ref<GenericFunction>;
 
   /// Build an array of substitutions from an interface type substitution map,
   /// using the given function to look up conformances.

include/swift/AST/Type.h

@@ -71,11 +71,11 @@ struct QueryTypeSubstitutionMap {
 };
 
 /// Function used to resolve conformances.
-using LookupConformanceFn
-  = llvm::function_ref<auto(CanType dependentType,
-                            Type conformingReplacementType,
-                            ProtocolType *conformedProtocol)
-                       -> Optional<ProtocolConformanceRef>>;
+using GenericFunction = auto(CanType dependentType,
+  Type conformingReplacementType,
+  ProtocolType *conformedProtocol)
+  ->Optional<ProtocolConformanceRef>;
+using LookupConformanceFn = llvm::function_ref<GenericFunction>;
 
 /// Functor class suitable for use as a \c LookupConformanceFn to look up a
 /// conformance through a module.