Merge pull request #24424 from harlanhaskins/an-absolutely-remarkable-thing

[ModuleInterface] Emit remarks when rebuilding from an interface

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))
 
@@ -278,6 +284,20 @@ 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+     "%select{compiled|cached|forwarding|prebuilt}0 module is out of date: '%1'",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+     "dependency is out of date: '%0'",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))
@@ -289,6 +309,7 @@ ERROR(unknown_forced_module_loading_mode,none,
 # if defined(DIAG)
 #  undef DIAG
 # endif
+# undef REMARK
 # undef NOTE
 # undef WARNING
 # undef ERROR

include/swift/Frontend/FrontendOptions.h

@@ -272,6 +272,10 @@ public:
   /// times) when compiling a module interface?
   bool SerializeModuleInterfaceDependencyHashes = false;
 
+  /// Should we warn if an imported module needed to be rebuilt from a
+  /// module interface file?
+  bool RemarkOnRebuildFromModuleInterface = false;
+
   /// The different modes for validating TBD against the LLVM IR.
   enum class TBDValidationMode {
     Default,        ///< Do the default validation for the current platform.

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

include/swift/Option/FrontendOptions.td

@@ -388,6 +388,9 @@ def warn_long_expression_type_checking : Separate<["-"], "warn-long-expression-t
 def warn_long_expression_type_checking_EQ : Joined<["-"], "warn-long-expression-type-checking=">,
   Alias<warn_long_expression_type_checking>;
 
+def Rmodule_interface_rebuild : Flag<["-"], "Rmodule-interface-rebuild">,
+  HelpText<"Emits a remark if an imported module needs to be re-compiled from its module interface">;
+
 def solver_expression_time_threshold_EQ : Joined<["-"], "solver-expression-time-threshold=">;
 
 def solver_disable_shrink :