[Dependency Scanning] Detect candidate files for .private interface files also

Author: artemcm

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1185,12 +1185,22 @@ std::error_code ModuleInterfaceLoader::findModuleFilesInDirectory(
 }
 
 std::vector<std::string>
-ModuleInterfaceCheckerImpl::getCompiledModuleCandidatesForInterface(
-    StringRef moduleName, StringRef interfacePath) {
+ModuleInterfaceCheckerImpl::getCompiledModuleCandidatesForInterface(StringRef moduleName, StringRef interfacePath) {
   // Derive .swiftmodule path from the .swiftinterface path.
+  auto interfaceExt = file_types::getExtension(file_types::TY_SwiftModuleInterfaceFile);
   auto newExt = file_types::getExtension(file_types::TY_SwiftModuleFile);
-  llvm::SmallString<32> modulePath = interfacePath;
-  llvm::sys::path::replace_extension(modulePath, newExt);
+  llvm::SmallString<32> modulePath;
+
+  // When looking up the module for a private interface, strip the '.private.' section of the base name
+  if (interfacePath.endswith(".private." + interfaceExt.str())) {
+    auto newBaseName = llvm::sys::path::stem(llvm::sys::path::stem(interfacePath));
+    modulePath = llvm::sys::path::parent_path(interfacePath);
+    llvm::sys::path::append(modulePath, newBaseName + "." + newExt.str());
+  } else {
+    modulePath = interfacePath;
+    llvm::sys::path::replace_extension(modulePath, newExt);
+  }
+
   ModuleInterfaceLoaderImpl Impl(Ctx, modulePath, interfacePath, moduleName,
                                  CacheDir, PrebuiltCacheDir, BackupInterfaceDir,
                                  SourceLoc(), Opts,

test/ScanDependencies/private_interface_candidate_module.swift

@@ -0,0 +1,27 @@
+// REQUIRES: objc_interop
+// RUN: %empty-directory(%t)
+// RUN: mkdir -p %t/clang-module-cache
+// RUN: mkdir -p %t/Frameworks
+// RUN: mkdir -p %t/Frameworks/E.framework/
+// RUN: mkdir -p %t/Frameworks/E.framework/Modules
+// RUN: mkdir -p %t/Frameworks/E.framework/Modules/E.swiftmodule
+
+// Copy over the interface
+// RUN: cp %S/Inputs/Swift/E.swiftinterface %t/Frameworks/E.framework/Modules/E.swiftmodule/%module-target-triple.private.swiftinterface
+// RUN: cp %S/Inputs/Swift/E.swiftinterface %t/Frameworks/E.framework/Modules/E.swiftmodule/%module-target-triple.swiftinterface
+
+// Build a dependency into a binary module
+// RUN: echo "public func foo() {}" >> %t/foo.swift
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/Frameworks/E.framework/Modules/E.swiftmodule/%module-target-triple.swiftmodule -module-cache-path %t.module-cache %t/foo.swift -module-name E
+
+// Run the scan
+// RUN: %target-swift-frontend -scan-dependencies %s -o %t/deps.json -F %t/Frameworks/ -sdk %t
+// RUN: %FileCheck %s < %t/deps.json
+
+import E
+
+// Ensure the private interface is the canonical one
+// CHECK: "moduleInterfacePath": {{.*}}{{/|\\}}E.framework{{/|\\}}Modules{{/|\\}}E.swiftmodule{{/|\\}}{{.*}}.private.swiftinterface
+// Ensure the adjacent binary module is a candidate
+// CHECK: "compiledModuleCandidates": [
+// CHECK-NEXT: {{.*}}{{/|\\}}E.framework{{/|\\}}Modules{{/|\\}}E.swiftmodule{{/|\\}}{{.*}}.swiftmodule