[ParseableInterface] Honor "exported module names"

(as described in the previous commit)

When printing an interface that has to be stable, we need to use the
module name that identifies where declarations should be searched for,
just like we do with serialization.

rdar://problem/49114811

Author: jrose-apple

include/swift/AST/PrintOptions.h

@@ -185,6 +185,12 @@ struct PrintOptions {
   /// type might be ambiguous.
   bool FullyQualifiedTypesIfAmbiguous = false;
 
+  /// If true, printed module names will use the "exported" name, which may be
+  /// different from the regular name.
+  ///
+  /// \see FileUnit::getExportedModuleName
+  bool UseExportedModuleNames = false;
+
   /// Print Swift.Array and Swift.Optional with sugared syntax
   /// ([] and ?), even if there are no sugar type nodes.
   bool SynthesizeSugarOnTypes = false;

lib/AST/ASTPrinter.cpp

@@ -99,6 +99,7 @@ PrintOptions PrintOptions::printParseableInterfaceFile() {
   result.TypeDefinitions = true;
   result.PrintIfConfig = false;
   result.FullyQualifiedTypes = true;
+  result.UseExportedModuleNames = true;
   result.AllowNullTypes = false;
   result.SkipImports = true;
   result.OmitNameOfInaccessibleProperties = true;
@@ -3342,8 +3343,14 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
 
   template <typename T>
   void printModuleContext(T *Ty) {
-    ModuleDecl *Mod = Ty->getDecl()->getModuleContext();
-    Printer.printModuleRef(Mod, Mod->getName());
+    FileUnit *File = cast<FileUnit>(Ty->getDecl()->getModuleScopeContext());
+    ModuleDecl *Mod = File->getParentModule();
+
+    Identifier Name = Mod->getName();
+    if (Options.UseExportedModuleNames)
+      Name = Mod->getASTContext().getIdentifier(File->getExportedModuleName());
+
+    Printer.printModuleRef(Mod, Name);
     Printer << ".";
   }
 

test/ParseableInterface/Inputs/exported-module-name-after/CoreKit.h

@@ -0,0 +1 @@
+#import <ExportAsCoreKit.h>

test/ParseableInterface/Inputs/exported-module-name-after/ExportAsCoreKit.h

@@ -0,0 +1,3 @@
+struct CKThing {
+  long value;
+};

test/ParseableInterface/Inputs/exported-module-name-after/module.modulemap

@@ -0,0 +1,5 @@
+module CoreKit {
+  header "CoreKit.h"
+  header "ExportAsCoreKit.h"
+  export *
+}

test/ParseableInterface/Inputs/exported-module-name-before/CoreKit.h

@@ -0,0 +1 @@
+#import <ExportAsCoreKit.h>

test/ParseableInterface/Inputs/exported-module-name-before/ExportAsCoreKit.h

@@ -0,0 +1,3 @@
+struct CKThing {
+  long value;
+};

test/ParseableInterface/Inputs/exported-module-name-before/module.modulemap

@@ -0,0 +1,10 @@
+module CoreKit {
+  header "CoreKit.h"
+  export *
+}
+
+module ExportAsCoreKit_BAD {
+  header "ExportAsCoreKit.h"
+  export_as CoreKit
+  export *
+}

test/ParseableInterface/exported-module-name.swift

@@ -0,0 +1,19 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -typecheck -emit-parseable-module-interface-path %t/CoreKitClient.swiftinterface -module-name CoreKitClient -I %S/Inputs/exported-module-name-before %s
+// RUN: %FileCheck -implicit-check-not BAD %s < %t/CoreKitClient.swiftinterface
+
+// Test that we can rebuild it even when the "export as" module goes away.
+// RUN: %target-swift-frontend -build-module-from-parseable-interface -o %t/CoreKitClient.swiftmodule -I %S/Inputs/exported-module-name-after %t/CoreKitClient.swiftinterface
+
+// CHECK: import CoreKit
+import CoreKit
+
+// CHECK-LABEL: public struct CKThingWrapper : RawRepresentable {
+public struct CKThingWrapper: RawRepresentable {
+  public var rawValue: CKThing
+  public init(rawValue: CKThing) {
+    self.rawValue = rawValue
+  }
+  // Note that this is CoreKit.CKThing, not ExportAsCoreKit.CKThing
+  // CHECK: public typealias RawValue = CoreKit.CKThing
+} // CHECK: {{^}$}}