[SymbolGraphGen] Import ObjC forward declarations by default. (#71947)

rdar://123279176

Author: sofiaromorales

lib/DriverTool/swift_symbolgraph_extract_main.cpp

@@ -142,6 +142,7 @@ int swift_symbolgraph_extract_main(ArrayRef<const char *> Args,
   }
   Invocation.setClangModuleCachePath(ModuleCachePath);
   Invocation.getClangImporterOptions().ModuleCachePath = ModuleCachePath;
+  Invocation.getClangImporterOptions().ImportForwardDeclarations = true;
   Invocation.setDefaultPrebuiltCacheIfNecessary();
 
   if (auto *A = ParsedArgs.getLastArg(OPT_swift_version)) {

test/SymbolGraph/ClangImporter/ImportForwardDeclarationsTest.swift

@@ -0,0 +1,9 @@
+// RUN: %empty-directory(%t)
+// RUN: cp -r %S/Inputs/ForwardDeclarations/ForwardDeclarations.framework %t
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -emit-module-path %t/ForwardDeclarations.framework/Modules/ForwardDeclarations.swiftmodule/%target-swiftmodule-name -import-underlying-module -F %t -module-name ForwardDeclarations -disable-objc-attr-requires-foundation-module %s
+// RUN: %target-swift-symbolgraph-extract -sdk %clang-importer-sdk -module-name ForwardDeclarations -F %t -output-dir %t -pretty-print -v
+// RUN: %FileCheck %s --input-file %t/ForwardDeclarations.symbols.json
+
+// REQUIRES: objc_interop
+
+// CHECK: "preciseIdentifier": "c:objc(cs)ForwardDeclaration"

test/SymbolGraph/ClangImporter/Inputs/ForwardDeclarations/ForwardDeclarations.framework/Headers/ForwardDeclaredInterfaceFoo.h

@@ -0,0 +1,9 @@
+@import Foundation;
+
+@class ForwardDeclaration;
+
+@interface Foo : NSObject
+
+@property ForwardDeclaration *foo;
+
+@end

test/SymbolGraph/ClangImporter/Inputs/ForwardDeclarations/ForwardDeclarations.framework/Modules/ForwardDeclarations.swiftmodule/.keep

@@ -0,0 +1,3 @@
+framework module ForwardDeclarations {
+    header "ForwardDeclaredInterfaceFoo.h"
+}