[ModuleInterface] Emit remarks when rebuilding from an interface

Keep track of information that led the module interface loader to reject loading a compiled module, if it needed to fall back to compiling an interface.

rdar://47792754

Author: Harlan Haskins

include/swift/AST/DiagnosticsFrontend.def

@@ -18,8 +18,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if !(defined(DIAG) || (defined(ERROR) && defined(WARNING) && defined(NOTE)))
-#  error Must define either DIAG or the set {ERROR,WARNING,NOTE}
+#if !(defined(DIAG) || (defined(ERROR) && defined(WARNING) && defined(NOTE) && \
+                        defined(REMARK)))
+#  error Must define either DIAG or the set {ERROR,WARNING,NOTE,REMARK}
 #endif
 
 #ifndef ERROR
@@ -37,6 +38,11 @@
   DIAG(NOTE,ID,Options,Text,Signature)
 #endif
 
+#ifndef REMARK
+#  define REMARK(ID,Options,Text,Signature)   \
+DIAG(REMARK,ID,Options,Text,Signature)
+#endif
+
 WARNING(warning_no_such_sdk,none,
         "no such SDK: '%0'", (StringRef))
 
@@ -271,6 +277,20 @@ ERROR(error_extracting_flags_from_module_interface,none,
 ERROR(missing_dependency_of_module_interface,none,
       "missing dependency '%0' of module interface '%1': %2",
       (StringRef, StringRef, StringRef))
+REMARK(rebuilding_module_from_interface,none,
+       "rebuilding module '%0' from interface '%1'", (StringRef, StringRef))
+NOTE(out_of_date_module_here,none,
+     "%select{compiled|cached|forwarding|prebuilt}0 module is out of date: '%1'",
+     (unsigned, StringRef))
+NOTE(module_interface_dependency_out_of_date,none,
+     "dependency is out of date: '%0'",
+     (StringRef))
+NOTE(compiled_module_invalid,none,
+     "unable to load compiled module '%0'",
+     (StringRef))
+NOTE(compiled_module_invalid_reason,none,
+     "unable to load compiled module '%0': %1",
+     (StringRef, StringRef))
 ERROR(error_extracting_dependencies_from_cached_module,none,
       "error extracting dependencies from cached module '%0'",
       (StringRef))
@@ -282,6 +302,7 @@ ERROR(unknown_forced_module_loading_mode,none,
 # if defined(DIAG)
 #  undef DIAG
 # endif
+# undef REMARK
 # undef NOTE
 # undef WARNING
 # undef ERROR

include/swift/Frontend/ParseableInterfaceModuleLoader.h

@@ -122,16 +122,18 @@ namespace swift {
 /// directory, and loading the serialized .swiftmodules from there.
 class ParseableInterfaceModuleLoader : public SerializedModuleLoaderBase {
   friend class unittest::ParseableInterfaceModuleLoaderTest;
-  explicit ParseableInterfaceModuleLoader(ASTContext &ctx, StringRef cacheDir,
-                                          StringRef prebuiltCacheDir,
-                                          DependencyTracker *tracker,
-                                          ModuleLoadingMode loadMode)
+  explicit ParseableInterfaceModuleLoader(
+      ASTContext &ctx, StringRef cacheDir, StringRef prebuiltCacheDir,
+      DependencyTracker *tracker, ModuleLoadingMode loadMode,
+      bool RemarkOnRebuildFromInterface)
   : SerializedModuleLoaderBase(ctx, tracker, loadMode),
-  CacheDir(cacheDir), PrebuiltCacheDir(prebuiltCacheDir)
+  CacheDir(cacheDir), PrebuiltCacheDir(prebuiltCacheDir),
+  RemarkOnRebuildFromInterface(RemarkOnRebuildFromInterface)
   {}
 
   std::string CacheDir;
   std::string PrebuiltCacheDir;
+  bool RemarkOnRebuildFromInterface;
 
   std::error_code findModuleFilesInDirectory(
     AccessPathElem ModuleID, StringRef DirPath, StringRef ModuleFilename,
@@ -144,10 +146,12 @@ class ParseableInterfaceModuleLoader : public SerializedModuleLoaderBase {
 public:
   static std::unique_ptr<ParseableInterfaceModuleLoader>
   create(ASTContext &ctx, StringRef cacheDir, StringRef prebuiltCacheDir,
-         DependencyTracker *tracker, ModuleLoadingMode loadMode) {
+         DependencyTracker *tracker, ModuleLoadingMode loadMode,
+         bool RemarkOnRebuildFromInterface = false) {
     return std::unique_ptr<ParseableInterfaceModuleLoader>(
       new ParseableInterfaceModuleLoader(ctx, cacheDir, prebuiltCacheDir,
-                                         tracker, loadMode));
+                                         tracker, loadMode,
+                                         RemarkOnRebuildFromInterface));
   }
 
   /// Unconditionally build \p InPath (a swiftinterface file) to \p OutPath (as

lib/Frontend/Frontend.cpp

@@ -339,13 +339,11 @@ bool CompilerInstance::setUpModuleLoaders() {
   if (MLM != ModuleLoadingMode::OnlySerialized) {
     auto const &Clang = clangImporter->getClangInstance();
     std::string ModuleCachePath = getModuleCachePathFromClang(Clang);
-    StringRef PrebuiltModuleCachePath =
-        Invocation.getFrontendOptions().PrebuiltModuleCachePath;
-    auto PIML = ParseableInterfaceModuleLoader::create(*Context,
-                                                       ModuleCachePath,
-                                                       PrebuiltModuleCachePath,
-                                                       getDependencyTracker(),
-                                                       MLM);
+    auto &FEOpts = Invocation.getFrontendOptions();
+    StringRef PrebuiltModuleCachePath = FEOpts.PrebuiltModuleCachePath;
+    auto PIML = ParseableInterfaceModuleLoader::create(
+        *Context, ModuleCachePath, PrebuiltModuleCachePath,
+        getDependencyTracker(), MLM, FEOpts.RemarkOnRebuildFromModuleInterface);
     Context->addModuleLoader(std::move(PIML));
   }
   Context->addModuleLoader(std::move(SML));