PrintAsObjc: expand module @imports to header #imports if modules are not supported

rdar://58284119

Author: nkcsgexi

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -319,6 +319,21 @@ static void writeImports(raw_ostream &out,
 
   // Track printed names to handle overlay modules.
   llvm::SmallPtrSet<Identifier, 8> seenImports;
+  llvm::SmallString<256> allPaths;
+  llvm::SmallSetVector<StringRef, 8> headerImports;
+  auto insertHeaderPath = [&](clang::Module::Header header,
+                              const clang::Module *module) {
+    auto startIdx = allPaths.size();
+    if (module->IsFramework) {
+      // For framworks, the header import should start from the framework name.
+      allPaths.append(module->getTopLevelModuleName());
+      llvm::sys::path::append(allPaths, header.NameAsWritten);
+    } else {
+      // Otherwise, import the header directly.
+      allPaths.append(header.NameAsWritten);
+    }
+    headerImports.insert(allPaths.str().substr(startIdx));
+  };
   bool includeUnderlying = false;
   for (auto import : sortedImports) {
     if (auto *swiftModule = import.dyn_cast<ModuleDecl *>()) {
@@ -327,17 +342,43 @@ static void writeImports(raw_ostream &out,
         includeUnderlying = true;
         continue;
       }
-      if (seenImports.insert(Name).second)
+      if (seenImports.insert(Name).second) {
         out << "@import " << Name.str() << ";\n";
+        if (auto *clangM = swiftModule->findUnderlyingClangModule()) {
+          if (auto umbrella = clangM->getUmbrellaHeader()) {
+            // If an umbrella header is available, use that.
+            insertHeaderPath(umbrella, clangM);
+          } else {
+            // Collect all headers included in the module.
+            for (auto headers: clangM->Headers) {
+              for (auto header: headers) {
+                insertHeaderPath(header, clangM);
+              }
+            }
+          }
+        }
+      }
     } else {
       const auto *clangModule = import.get<const clang::Module *>();
       assert(clangModule->isSubModule() &&
              "top-level modules should use a normal swift::ModuleDecl");
       out << "@import ";
       ModuleDecl::ReverseFullNameIterator(clangModule).printForward(out);
       out << ";\n";
+      // Collect all headers included in the submodule
+      for (auto headers: clangModule->Headers) {
+         for (auto header: headers) {
+           insertHeaderPath(header, clangModule);
+         }
+       }
     }
   }
+  out << "#else\n";
+
+  // We cannot use module import, so use header includes instead.
+  for (auto header: headerImports) {
+    out << "#import <" << header << ">\n";
+  }
 
   out << "#endif\n\n";
 

test/Inputs/clang-importer-sdk/swift-modules/Foundation.swift

@@ -238,7 +238,7 @@ public func _convertNSErrorToError(_ error: NSError?) -> Error {
 }
 
 public func _convertErrorToNSError(_ x: Error) -> NSError {
-  return x as NSError
+  return unsafeDowncast(_bridgeErrorToNSError(x), to: NSError.self)
 }
 
 extension _SwiftNewtypeWrapper where Self.RawValue == Error {

test/PrintAsObjC/classes.swift

@@ -17,7 +17,7 @@
 // RUN: %FileCheck %s < %t/classes.h
 // RUN: %FileCheck --check-prefix=NEGATIVE %s < %t/classes.h
 // RUN: %check-in-clang -I %S/Inputs/custom-modules/ %t/classes.h
-// RUN: not %check-in-clang -I %S/Inputs/custom-modules/ -fno-modules -Qunused-arguments %t/classes.h
+// RUN: %check-in-clang -I %S/Inputs/custom-modules/ -fno-modules -Qunused-arguments %t/classes.h
 // RUN: %check-in-clang -I %S/Inputs/custom-modules/ -fno-modules -Qunused-arguments %t/classes.h -include CoreFoundation.h -include objc_generics.h -include SingleGenericClass.h -include CompatibilityAlias.h
 
 // CHECK-NOT: AppKit;

test/PrintAsObjC/empty.swift

@@ -38,6 +38,7 @@
 // CHECK-NEXT: #if __has_warning
 // CHECK-NEXT: #pragma clang diagnostic
 // CHECK-NEXT: #endif
+// CHECK-NEXT: #else
 // CHECK-NEXT: #endif
 
 

test/PrintAsObjC/imports.swift

@@ -20,6 +20,16 @@
 // CHECK-NEXT: @import ObjectiveC;
 // CHECK-NEXT: @import ctypes.bits;
 
+// CHECK-NEXT: #else
+// CHECK-NEXT: #import <Base.ExplicitSub.h>
+// CHECK-NEXT: #import <Base.ExplicitSub.ExSub.h>
+// CHECK-NEXT: #import <Base.ImplicitSub.ExSub.h>
+// CHECK-NEXT: #import <Foundation.h>
+// CHECK-NEXT: #import <MostlyPrivate1/MostlyPrivate1.h>
+// CHECK-NEXT: #import <MostlyPrivate1_Private/MostlyPrivate1_Private.h>
+// CHECK-NEXT: #import <MostlyPrivate2_Private/MostlyPrivate2_Private.h>
+// CHECK-NEXT: #import <ctypes/bits.h>
+
 // NEGATIVE-NOT: ctypes;
 // NEGATIVE-NOT: ImSub;
 // NEGATIVE-NOT: ImplicitSub;

test/PrintAsObjC/mixed-framework-fwd.swift

@@ -22,6 +22,8 @@
 // CHECK-NEXT: #pragma clang diagnostic
 // CHECK-NEXT: #endif
 // CHECK-NEXT: @import Foundation;
+// CHECK-NEXT: #else
+// CHECK-NEXT: #import <Foundation.h>
 // CHECK-NEXT: #endif
 
 // NO-IMPORT-NOT: #import

test/PrintAsObjC/mixed-framework.swift

@@ -17,6 +17,8 @@
 // CHECK-NEXT: #pragma clang diagnostic ignored "-Watimport-in-framework-header"
 // CHECK-NEXT: #endif
 // CHECK-NEXT: @import Foundation;
+// CHECK-NEXT: #else
+// CHECK-NEXT: #import <Foundation.h>
 // CHECK-NEXT: #endif
 
 // FRAMEWORK-LABEL: #import <Mixed/Mixed.h>