[interop] clear importer decl when emitting symbolic interface

This ensures that our interface do not reference already instantiated and imported specializations.

Author: hyp

include/swift/AST/PrintOptions.h

@@ -562,10 +562,6 @@ struct PrintOptions {
   /// If false, we print them as ordinary associated types.
   bool PrintPrimaryAssociatedTypes = true;
 
-  /// If true, import and print C++ declarations with symbolic import feature
-  /// enabled.
-  bool PrintSymbolicCXXDecls = false;
-
   /// If this is not \c nullptr then function bodies (including accessors
   /// and constructors) will be printed by this function.
   std::function<void(const ValueDecl *, ASTPrinter &)> FunctionBody;

include/swift/ClangImporter/ClangImporter.h

@@ -556,8 +556,8 @@ class ClangImporter final : public ClangModuleLoader {
   /// of the provided baseType.
   void diagnoseMemberValue(const DeclName &name, const Type &baseType) override;
 
-  /// Enable/disable the symbolic import experimental feature.
-  void enableSymbolicImportFeature(bool isEnabled = true);
+  /// Enable the symbolic import experimental feature for the given callback.
+  void withSymbolicFeatureEnabled(llvm::function_ref<void(void)> callback);
 };
 
 ImportDecl *createImportDecl(ASTContext &Ctx, DeclContext *DC, ClangNode ClangN,

lib/ClangImporter/ClangImporter.cpp

@@ -6565,9 +6565,17 @@ CustomRefCountingOperationResult CustomRefCountingOperation::evaluate(
   return {CustomRefCountingOperationResult::tooManyFound, nullptr, name};
 }
 
-void ClangImporter::enableSymbolicImportFeature(bool isEnabled) {
-  Impl.importSymbolicCXXDecls = isEnabled;
-  Impl.nameImporter->enableSymbolicImportFeature(isEnabled);
+void ClangImporter::withSymbolicFeatureEnabled(
+    llvm::function_ref<void(void)> callback) {
+  llvm::SaveAndRestore<bool> oldImportSymbolicCXXDecls(
+      Impl.importSymbolicCXXDecls, true);
+  Impl.nameImporter->enableSymbolicImportFeature(true);
+  auto importedDeclsCopy = Impl.ImportedDecls;
+  Impl.ImportedDecls.clear();
+  callback();
+  Impl.ImportedDecls = std::move(importedDeclsCopy);
+  Impl.nameImporter->enableSymbolicImportFeature(
+      oldImportSymbolicCXXDecls.get());
 }
 
 bool importer::requiresCPlusPlus(const clang::Module *module) {

lib/IDE/ModuleInterfacePrinting.cpp

@@ -544,18 +544,6 @@ void swift::ide::printModuleInterface(
   auto &SwiftContext = TopLevelMod->getASTContext();
   auto &Importer =
       static_cast<ClangImporter &>(*SwiftContext.getClangModuleLoader());
-  if (Options.PrintSymbolicCXXDecls)
-    Importer.enableSymbolicImportFeature(true);
-  struct SymbolicImportRAII {
-    bool PrintSymbolicCXXDecls;
-    ClangImporter &Importer;
-    SymbolicImportRAII(bool PrintSymbolicCXXDecls, ClangImporter &Importer)
-        : PrintSymbolicCXXDecls(PrintSymbolicCXXDecls), Importer(Importer) {}
-    ~SymbolicImportRAII() {
-      if (PrintSymbolicCXXDecls)
-        Importer.enableSymbolicImportFeature(false);
-    }
-  } deferDisableSymbolicImport(Options.PrintSymbolicCXXDecls, Importer);
 
   auto AdjustedOptions = Options;
   adjustPrintOptions(AdjustedOptions);
@@ -1159,9 +1147,14 @@ void swift::ide::printSymbolicSwiftClangModuleInterface(
   opts |= ModuleTraversal::VisitSubmodules;
   auto popts =
       PrintOptions::printModuleInterface(/*printFullConvention=*/false);
-  popts.PrintSymbolicCXXDecls = true;
   popts.PrintDocumentationComments = false;
   popts.PrintRegularClangComments = false;
-  printModuleInterface(M, {}, opts, Printer, popts,
-                       /*SynthesizeExtensions=*/false);
+
+  auto &SwiftContext = M->getTopLevelModule()->getASTContext();
+  auto &Importer =
+      static_cast<ClangImporter &>(*SwiftContext.getClangModuleLoader());
+  Importer.withSymbolicFeatureEnabled([&]() {
+    printModuleInterface(M, {}, opts, Printer, popts,
+                         /*SynthesizeExtensions=*/false);
+  });
 }

test/Interop/Cxx/symbolic-imports/indexing-emit-symbolic-module-interface-used-decls.swift

@@ -0,0 +1,41 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend %t/test.swift -I %t -c -index-system-modules -index-store-path %t/store -enable-experimental-cxx-interop 2>&1
+// RUN: cat %t/store/interfaces/CxxModule* | %FileCheck --check-prefix=CHECK %s
+
+//--- Inputs/module.modulemap
+module CxxModule {
+    header "header.h"
+    requires cplusplus
+}
+
+//--- Inputs/header.h
+
+namespace ns {
+    template<class T>
+    struct TemplateRecord {
+        void methodFunc(int x) const;
+    };
+}
+
+using TemplateRecordInt = ns::TemplateRecord<int>;
+
+//--- test.swift
+
+import CxxModule
+
+public func useConcreteTemplate() {
+    let x = TemplateRecordInt()
+    x.methodFunc(2)
+}
+
+// CHECK: // Swift interface for module 'CxxModule'
+// CHECK:     public enum ns {
+// CHECK-EMPTY:
+// CHECK-NEXT: public struct TemplateRecord {
+// CHECK-EMPTY:
+// CHECK-NEXT:    public func methodFunc()
+// CHECK-NEXT:}
+// CHECK-NEXT:}
+// CHECK-NEXT: public typealias TemplateRecordInt = ns.TemplateRecord