Add -testable-import-module frontend flag

This is just like -import-module, but it does an @testable import. Simple, right?

Fixes rdar://66544654.

Author: beccadax

include/swift/Frontend/FrontendOptions.h

@@ -34,7 +34,8 @@ class FrontendOptions {
   friend class ArgsToFrontendOptionsConverter;
 
   /// A list of arbitrary modules to import and make implicitly visible.
-  std::vector<std::string> ImplicitImportModuleNames;
+  std::vector<std::pair<std::string, bool /*testable*/>>
+      ImplicitImportModuleNames;
 
 public:
   FrontendInputsAndOutputs InputsAndOutputs;
@@ -351,7 +352,8 @@ class FrontendOptions {
 
   /// Retrieves the list of arbitrary modules to import and make implicitly
   /// visible.
-  ArrayRef<std::string> getImplicitImportModuleNames() const {
+  ArrayRef<std::pair<std::string, bool /*testable*/>>
+  getImplicitImportModuleNames() const {
     return ImplicitImportModuleNames;
   }
 

include/swift/Option/FrontendOptions.td

@@ -512,6 +512,9 @@ def enable_throw_without_try : Flag<["-"], "enable-throw-without-try">,
 def import_module : Separate<["-"], "import-module">,
   HelpText<"Implicitly import the specified module">;
 
+def testable_import_module : Separate<["-"], "testable-import-module">,
+  HelpText<"Implicitly import the specified module with @testable">;
+
 def print_stats : Flag<["-"], "print-stats">,
   HelpText<"Print various statistics">;
 

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -215,7 +215,8 @@ bool ArgsToFrontendOptionsConverter::convert(
   Opts.DisableBuildingInterface = Args.hasArg(OPT_disable_building_interface);
 
   computeImportObjCHeaderOptions();
-  computeImplicitImportModuleNames();
+  computeImplicitImportModuleNames(OPT_import_module, /*isTestable=*/false);
+  computeImplicitImportModuleNames(OPT_testable_import_module, /*isTestable=*/true);
   computeLLVMArgs();
 
   return false;
@@ -586,16 +587,17 @@ void ArgsToFrontendOptionsConverter::computeImportObjCHeaderOptions() {
     Opts.SerializeBridgingHeader |= !Opts.InputsAndOutputs.hasPrimaryInputs();
   }
 }
-void ArgsToFrontendOptionsConverter::computeImplicitImportModuleNames() {
+void ArgsToFrontendOptionsConverter::
+computeImplicitImportModuleNames(OptSpecifier id, bool isTestable) {
   using namespace options;
-  for (const Arg *A : Args.filtered(OPT_import_module)) {
+  for (const Arg *A : Args.filtered(id)) {
     auto *moduleStr = A->getValue();
     if (!Lexer::isIdentifier(moduleStr)) {
       Diags.diagnose(SourceLoc(), diag::error_bad_module_name, moduleStr,
                      /*suggestModuleNameFlag*/ false);
       continue;
     }
-    Opts.ImplicitImportModuleNames.push_back(moduleStr);
+    Opts.ImplicitImportModuleNames.emplace_back(moduleStr, isTestable);
   }
 }
 void ArgsToFrontendOptionsConverter::computeLLVMArgs() {

lib/Frontend/ArgsToFrontendOptionsConverter.h

@@ -40,7 +40,8 @@ class ArgsToFrontendOptionsConverter {
   bool computeMainAndSupplementaryOutputFilenames();
   void computeDumpScopeMapLocations();
   void computeHelpOptions();
-  void computeImplicitImportModuleNames();
+  void computeImplicitImportModuleNames(llvm::opt::OptSpecifier id,
+                                        bool isTestable);
   void computeImportObjCHeaderOptions();
   void computeLLVMArgs();
   void computePlaygroundOptions();

lib/Frontend/Frontend.cpp

@@ -740,15 +740,18 @@ ImplicitImportInfo CompilerInstance::getImplicitImportInfo() const {
   ImplicitImportInfo imports;
   imports.StdlibKind = Invocation.getImplicitStdlibKind();
 
-  auto pushImport = [&](StringRef moduleStr) {
+  auto pushImport = [&](StringRef moduleStr,
+                        ImportOptions options = ImportOptions()) {
     ImportPath::Builder importPath(Context->getIdentifier(moduleStr));
     UnloadedImportedModule import(importPath.copyTo(*Context),
                                   /*isScoped=*/false);
-    imports.AdditionalUnloadedImports.emplace_back(import, ImportOptions());
+    imports.AdditionalUnloadedImports.emplace_back(import, options);
   };
 
-  for (auto &moduleStr : frontendOpts.getImplicitImportModuleNames()) {
-    pushImport(moduleStr);
+  for (auto &moduleStrAndTestable : frontendOpts.getImplicitImportModuleNames()) {
+    pushImport(moduleStrAndTestable.first,
+               moduleStrAndTestable.second ? ImportFlags::Testable
+                                           : ImportOptions());
   }
 
   if (Invocation.shouldImportSwiftONoneSupport()) {

test/ImportResolution/import-command-line.swift

@@ -7,5 +7,8 @@
 // RUN: not %target-swift-frontend -typecheck %s -enable-source-import -I %S/Inputs -sdk "" -import-module NON_EXISTENT 2>&1 | %FileCheck -check-prefix=NON-EXISTENT %s
 // NON-EXISTENT: error: no such module 'NON_EXISTENT'
 
+// RUN: not %target-swift-frontend -typecheck %s -enable-source-import -I %S/Inputs -sdk "" -testable-import-module abcde 2>&1 | %FileCheck -check-prefix=NON-TESTABLE %s
+// NON-TESTABLE: error: module 'abcde' was not compiled for testing
+
 var a: A? // expected-error {{cannot find type 'A' in scope}}
 var qA: abcde.A? // expected-error {{cannot find type 'abcde' in scope}}

tools/SourceKit/lib/SwiftLang/CodeCompletionOrganizer.cpp

@@ -347,9 +347,9 @@ ImportDepth::ImportDepth(ASTContext &context,
   // Imports from -import-name such as Playground auxiliary sources are treated
   // specially by applying import depth 0.
   llvm::StringSet<> auxImports;
-  for (StringRef moduleName :
+  for (const auto &pair :
        invocation.getFrontendOptions().getImplicitImportModuleNames())
-    auxImports.insert(moduleName);
+    auxImports.insert(pair.first);
 
   // Private imports from this module.
   // FIXME: only the private imports from the current source file.