Track Clang function types in the AST

include/swift/AST/ASTContext.h

@@ -22,6 +22,7 @@
 #include "swift/AST/Identifier.h"
 #include "swift/AST/SearchPathOptions.h"
 #include "swift/AST/Type.h"
+#include "swift/AST/Types.h"
 #include "swift/AST/TypeAlignments.h"
 #include "swift/Basic/LangOptions.h"
 #include "swift/Basic/Malloc.h"
@@ -557,6 +558,19 @@ class ASTContext final {
   Type getBridgedToObjC(const DeclContext *dc, Type type,
                         Type *bridgedValueType = nullptr) const;
 
+  /// Get the Clang type corresponding to a Swift function type.
+  ///
+  /// \param params The function parameters.
+  /// \param resultTy The Swift result type.
+  /// \param incompleteExtInfo Used to convey escaping and throwing
+  ///                          information, in case it is needed.
+  /// \param trueRep The actual calling convention, which must be C-compatible.
+  ///                The calling convention in \p incompleteExtInfo is ignored.
+  const clang::Type *
+  getClangFunctionType(ArrayRef<AnyFunctionType::Param> params, Type resultTy,
+                       const FunctionType::ExtInfo incompleteExtInfo,
+                       FunctionTypeRepresentation trueRep);
+
   /// Determine whether the given Swift type is representable in a
   /// given foreign language.
   ForeignRepresentationInfo

include/swift/AST/ClangModuleLoader.h

@@ -20,6 +20,7 @@ class ASTContext;
 class CompilerInstance;
 class Preprocessor;
 class Sema;
+class TargetInfo;
 } // namespace clang
 
 namespace swift {
@@ -46,6 +47,7 @@ class ClangModuleLoader : public ModuleLoader {
   using ModuleLoader::ModuleLoader;
 
 public:
+  virtual clang::TargetInfo &getTargetInfo() const = 0;
   virtual clang::ASTContext &getClangASTContext() const = 0;
   virtual clang::Preprocessor &getClangPreprocessor() const = 0;
   virtual clang::Sema &getClangSema() const = 0;

include/swift/AST/ClangSwiftTypeCorrespondence.h

@@ -0,0 +1,36 @@
+//=- ClangSwiftTypeCorrespondence.h - Relations between Clang & Swift types -=//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2019 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes some common relations between Clang types and Swift
+// types that are need by the ClangTypeConverter and parts of ClangImporter.
+//
+// Since ClangTypeConverter is an implementation detail, ClangImporter should
+// not depend on ClangTypeConverter.h.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_AST_CLANG_SWIFT_TYPE_CORRESPONDENCE_H
+#define SWIFT_AST_CLANG_SWIFT_TYPE_CORRESPONDENCE_H
+
+namespace clang {
+class Type;
+}
+
+namespace swift {
+/// Checks whether a Clang type can be imported as a Swift Optional type.
+///
+/// For example, a `const uint8_t *` could be imported as
+/// `Optional<UnsafePointer<UInt8>>`.
+bool canImportAsOptional(const clang::Type *type);
+}
+
+#endif /* SWIFT_AST_CLANG_SWIFT_TYPE_CORRESPONDENCE_H */