[ASTGen] Implement bridging for using declaration

Author: xedin

include/swift/AST/ASTBridging.h

@@ -1744,6 +1744,19 @@ BridgedImportDecl BridgedImportDecl_createParsed(
     BridgedSourceLoc cImportKeywordLoc, BridgedImportKind cImportKind,
     BridgedSourceLoc cImportKindLoc, BridgedArrayRef cImportPathElements);
 
+enum ENUM_EXTENSIBILITY_ATTR(open) BridgedUsingSpecifier {
+  BridgedUsingSpecifierMainActor,
+  BridgedUsingSpecifierNonisolated,
+};
+
+SWIFT_NAME("BridgedUsingDecl.createParsed(_:declContext:usingKeywordLoc:"
+           "specifierLoc:specifier:)")
+BridgedUsingDecl BridgedUsingDecl_createParsed(BridgedASTContext cContext,
+                                               BridgedDeclContext cDeclContext,
+                                               BridgedSourceLoc usingKeywordLoc,
+                                               BridgedSourceLoc specifierLoc,
+                                               BridgedUsingSpecifier specifier);
+
 SWIFT_NAME("BridgedSubscriptDecl.createParsed(_:declContext:staticLoc:"
            "staticSpelling:subscriptKeywordLoc:genericParamList:parameterList:"
            "arrowLoc:returnType:genericWhereClause:)")

lib/AST/Bridging/DeclBridging.cpp

@@ -637,6 +637,17 @@ BridgedImportDecl BridgedImportDecl_createParsed(
       std::move(builder).get());
 }
 
+BridgedUsingDecl BridgedUsingDecl_createParsed(BridgedASTContext cContext,
+                                               BridgedDeclContext cDeclContext,
+                                               BridgedSourceLoc usingKeywordLoc,
+                                               BridgedSourceLoc specifierLoc,
+                                               BridgedUsingSpecifier specifier) {
+  ASTContext &ctx = cContext.unbridged();
+  return UsingDecl::create(
+      ctx, usingKeywordLoc.unbridged(), specifierLoc.unbridged(),
+      static_cast<UsingSpecifier>(specifier), cDeclContext.unbridged());
+}
+
 BridgedSubscriptDecl BridgedSubscriptDecl_createParsed(
     BridgedASTContext cContext, BridgedDeclContext cDeclContext,
     BridgedSourceLoc cStaticLoc, BridgedStaticSpelling cStaticSpelling,

lib/ASTGen/Sources/ASTGen/Decls.swift

@@ -69,6 +69,8 @@ extension ASTGenVisitor {
       return self.generate(typeAliasDecl: node)?.asDecl
     case .variableDecl(let node):
       return self.generate(variableDecl: node)
+    case .usingDecl(let node):
+      return self.generate(usingDecl: node)?.asDecl
     }
   }
 
@@ -1083,6 +1085,35 @@ extension ASTGenVisitor {
   }
 }
 
+extension ASTGenVisitor {
+  func generate(usingDecl node: UsingDeclSyntax) -> BridgedUsingDecl? {
+    var specifier: BridgedUsingSpecifier? = nil
+
+    switch node.specifier {
+    case .attribute(let attr):
+      if attr.attributeName == TypeSyntax("MainActor") {
+        specifier = .mainActor
+      }
+    case .modifier(let modifier):
+      if case .keyword(.nonisolated) = modifier.tokenKind {
+        specifier = .nonisolated
+      }
+    }
+
+    guard let specifier else {
+      return nil
+    }
+
+    return BridgedUsingDecl.createParsed(
+      self.ctx,
+      declContext: self.declContext,
+      usingKeywordLoc: self.generateSourceLoc(node.usingKeyword),
+      specifierLoc: self.generateSourceLoc(node.specifier),
+      specifier: specifier
+    )
+  }
+}
+
 extension ASTGenVisitor {
   func generate(memberBlockItem node: MemberBlockItemSyntax) -> BridgedDecl? {
     if let node = node.decl.as(MacroExpansionDeclSyntax.self) {