[🦩] Add swiftASTGen library to build a C++ AST from a SwiftSyntax parse tree

include/swift/AST/CASTBridging.h

@@ -0,0 +1,144 @@
+//===--- ASTBridging.h - header for the swift SILBridging module ----------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2022 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_C_AST_ASTBRIDGING_H
+#define SWIFT_C_AST_ASTBRIDGING_H
+
+#include <inttypes.h>
+
+#if __clang__
+// Provide macros to temporarily suppress warning about the use of
+// _Nullable and _Nonnull.
+#define SWIFT_BEGIN_NULLABILITY_ANNOTATIONS                                    \
+  _Pragma("clang diagnostic push")                                             \
+      _Pragma("clang diagnostic ignored \"-Wnullability-extension\"")          \
+          _Pragma("clang assume_nonnull begin")
+
+#define SWIFT_END_NULLABILITY_ANNOTATIONS                                      \
+  _Pragma("clang diagnostic pop") _Pragma("clang assume_nonnull end")
+#else
+#define SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+#define SWIFT_END_NULLABILITY_ANNOTATIONS
+#define _Nullable
+#endif
+
+SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+
+typedef long SwiftInt;
+typedef unsigned long SwiftUInt;
+
+typedef struct {
+  const void *_Nullable data;
+  long numElements;
+} BridgedArrayRef;
+
+typedef struct {
+  void *start;
+  SwiftInt byteLength;
+} BridgedCharSourceRange;
+
+typedef void *BridgedIdentifier;
+
+#ifdef __cplusplus
+extern "C" {
+
+#define _Bool bool
+
+#endif
+
+BridgedIdentifier
+SwiftASTContext_getIdentifier(
+    void *ctx, const uint8_t * _Nullable str, long len);
+
+void *SwiftImportDecl_create(void *, void *, void *, char, void *,
+                             BridgedArrayRef, BridgedArrayRef);
+
+void *SwiftTopLevelCodeDecl_createStmt(void *ctx, void *DC, void *startLoc,
+                                       void *element, void *endLoc);
+void *SwiftTopLevelCodeDecl_createExpr(void *ctx, void *DC, void *startLoc,
+                                       void *element, void *endLoc);
+
+void *SwiftSequenceExpr_create(void *ctx, BridgedArrayRef exprs);
+
+void *SwiftTupleExpr_create(void *ctx, void *lparen, BridgedArrayRef subs,
+                            void *rparen);
+
+void *SwiftFunctionCallExpr_create(void *ctx, void *fn, void *args);
+
+void *SwiftIdentifierExpr_create(void *ctx, BridgedIdentifier base, void *loc);
+
+void *SwiftStringLiteralExpr_create(void *ctx, const uint8_t * _Nullable string,
+                                    long len, void *TokenLoc);
+
+void *SwiftIntegerLiteralExpr_create(void *ctx, const uint8_t * _Nullable string,
+                                    long len, void *TokenLoc);
+
+void *SwiftBooleanLiteralExpr_create(void *ctx, _Bool value, void *TokenLoc);
+
+void *SwiftVarDecl_create(void *ctx, BridgedIdentifier _Nullable name,
+                          void *loc, _Bool isStatic, _Bool isLet, void *dc);
+
+void *IfStmt_create(void *ctx, void *ifLoc, void *cond, void *_Nullable then, void *_Nullable elseLoc,
+                    void *_Nullable elseStmt);
+
+void *BraceStmt_createExpr(void *ctx, void *lbloc, BridgedArrayRef elements, void *rbloc);
+void *BraceStmt_createStmt(void *ctx, void *lbloc, BridgedArrayRef elements, void *rbloc);
+
+void *BridgedSourceLoc_advanced(void *loc, long len);
+
+void *ParamDecl_create(void *ctx, void *loc,
+                       void *_Nullable argLoc, void *_Nullable argName,
+                       void *_Nullable paramLoc, void *_Nullable paramName,
+                       void *declContext);
+
+void *FuncDecl_create(void *ctx, void *staticLoc, _Bool isStatic, void *funcLoc,
+                      BridgedIdentifier name, void *nameLoc,
+                      _Bool isAsync, void *_Nullable asyncLoc,
+                      _Bool throws, void *_Nullable throwsLoc,
+                      void *paramLLoc, BridgedArrayRef params, void *paramRLoc,
+                      void *_Nullable body, void *_Nullable returnType,
+                      void *declContext);
+
+void *SimpleIdentTypeRepr_create(void *ctx, void *loc, BridgedIdentifier id);
+
+void *UnresolvedDotExpr_create(void *ctx, void *base, void *dotLoc, BridgedIdentifier name, void *nameLoc);
+
+void *ClosureExpr_create(void *ctx, void *body, void *dc);
+
+void NominalTypeDecl_setMembers(void *decl, BridgedArrayRef members);
+
+struct DeclContextAndDecl {
+  void *declContext;
+  void *nominalDecl;
+  void *decl;
+};
+
+struct DeclContextAndDecl StructDecl_create(
+    void *ctx, void *loc, BridgedIdentifier name, void *nameLoc, void *dc);
+struct DeclContextAndDecl ClassDecl_create(
+    void *ctx, void *loc, BridgedIdentifier name, void *nameLoc, void *dc);
+
+void TopLevelCodeDecl_dump(void *);
+void Expr_dump(void *);
+void Decl_dump(void *);
+void Stmt_dump(void *);
+
+#ifdef __cplusplus
+}
+#endif
+
+SWIFT_END_NULLABILITY_ANNOTATIONS
+
+#undef SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+#undef SWIFT_END_NULLABILITY_ANNOTATIONS
+
+#endif // SWIFT_C_AST_ASTBRIDGING_H

include/swift/Basic/Features.def

@@ -141,6 +141,10 @@ EXPERIMENTAL_FEATURE(ParserSequenceFolding)
 /// Enables implicit some while also enabling existential `any`
 EXPERIMENTAL_FEATURE(ImplicitSome)
 
+/// Parse using the Swift (swift-syntax) parser and use ASTGen to generate the
+/// corresponding syntax tree.
+EXPERIMENTAL_FEATURE(ParserASTGen)
+
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE
 #undef SUPPRESSIBLE_LANGUAGE_FEATURE

include/swift/module.modulemap

@@ -15,6 +15,10 @@ module ASTBridging {
   export *
 }
 
+module CASTBridging {
+  header "AST/CASTBridging.h"
+}
+
 module SILBridging {
   header "SIL/SILBridging.h"
   header "SIL/SILLocation.h"

lib/AST/ASTPrinter.cpp

@@ -3091,6 +3091,10 @@ static bool usesFeatureAdditiveArithmeticDerivedConformances(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureParserASTGen(Decl *decl) {
+  return false;
+}
+
 static void
 suppressingFeatureNoAsyncAvailability(PrintOptions &options,
                                       llvm::function_ref<void()> action) {