[ModuleInterface] Pass -Rmodule-interface-rebuild to sub-invocation

include/swift/Frontend/ParseableInterfaceModuleLoader.h

@@ -167,7 +167,8 @@ class ParseableInterfaceModuleLoader : public SerializedModuleLoaderBase {
   static bool buildSwiftModuleFromSwiftInterface(
     ASTContext &Ctx, StringRef CacheDir, StringRef PrebuiltCacheDir,
     StringRef ModuleName, StringRef InPath, StringRef OutPath,
-    bool SerializeDependencyHashes, bool TrackSystemDependencies);
+    bool SerializeDependencyHashes, bool TrackSystemDependencies,
+    bool RemarkOnRebuildFromInterface);
 };
 
 /// Extract the specified-or-defaulted -module-cache-path that winds up in

lib/Frontend/ParseableInterfaceModuleLoader.cpp

@@ -289,6 +289,7 @@ class swift::ParseableInterfaceBuilder {
   const StringRef prebuiltCachePath;
   const bool serializeDependencyHashes;
   const bool trackSystemDependencies;
+  const bool remarkOnRebuildFromInterface;
   const SourceLoc diagnosticLoc;
   DependencyTracker *const dependencyTracker;
   CompilerInvocation subInvocation;
@@ -350,7 +351,12 @@ class swift::ParseableInterfaceBuilder {
     // Tell the subinvocation to serialize dependency hashes if asked to do so.
     auto &frontendOpts = subInvocation.getFrontendOptions();
     frontendOpts.SerializeModuleInterfaceDependencyHashes =
-      serializeDependencyHashes;
+        serializeDependencyHashes;
+
+    // Tell the subinvocation to remark on rebuilds from an interface if asked
+    // to do so.
+    frontendOpts.RemarkOnRebuildFromModuleInterface =
+        remarkOnRebuildFromInterface;
   }
 
   bool extractSwiftInterfaceVersionAndArgs(
@@ -473,13 +479,15 @@ class swift::ParseableInterfaceBuilder {
                             StringRef prebuiltCachePath,
                             bool serializeDependencyHashes = false,
                             bool trackSystemDependencies = false,
+                            bool remarkOnRebuildFromInterface = false,
                             SourceLoc diagnosticLoc = SourceLoc(),
                             DependencyTracker *tracker = nullptr)
   : ctx(ctx), fs(*ctx.SourceMgr.getFileSystem()), diags(ctx.Diags),
   interfacePath(interfacePath), moduleName(moduleName),
   moduleCachePath(moduleCachePath), prebuiltCachePath(prebuiltCachePath),
   serializeDependencyHashes(serializeDependencyHashes),
   trackSystemDependencies(trackSystemDependencies),
+  remarkOnRebuildFromInterface(remarkOnRebuildFromInterface),
   diagnosticLoc(diagnosticLoc), dependencyTracker(tracker) {
     configureSubInvocation();
   }
@@ -1230,7 +1238,7 @@ class ParseableInterfaceModuleLoaderImpl {
     ParseableInterfaceBuilder builder(
       ctx, interfacePath, moduleName, cacheDir, prebuiltCacheDir,
       /*serializeDependencyHashes*/false, trackSystemDependencies,
-      diagnosticLoc, dependencyTracker);
+      remarkOnRebuildFromInterface, diagnosticLoc, dependencyTracker);
     auto &subInvocation = builder.getSubInvocation();
 
     // Compute the output path if we're loading or emitting a cached module.
@@ -1367,11 +1375,13 @@ std::error_code ParseableInterfaceModuleLoader::findModuleFilesInDirectory(
 bool ParseableInterfaceModuleLoader::buildSwiftModuleFromSwiftInterface(
   ASTContext &Ctx, StringRef CacheDir, StringRef PrebuiltCacheDir,
   StringRef ModuleName, StringRef InPath, StringRef OutPath,
-  bool SerializeDependencyHashes, bool TrackSystemDependencies) {
+  bool SerializeDependencyHashes, bool TrackSystemDependencies,
+  bool RemarkOnRebuildFromInterface) {
   ParseableInterfaceBuilder builder(Ctx, InPath, ModuleName,
                                     CacheDir, PrebuiltCacheDir,
                                     SerializeDependencyHashes,
-                                    TrackSystemDependencies);
+                                    TrackSystemDependencies,
+                                    RemarkOnRebuildFromInterface);
   // FIXME: We really only want to serialize 'important' dependencies here, if
   //        we want to ship the built swiftmodules to another machine.
   return builder.buildSwiftModule(OutPath, /*shouldSerializeDeps*/true,

lib/FrontendTool/FrontendTool.cpp

@@ -602,7 +602,7 @@ static bool buildModuleFromParseableInterface(CompilerInvocation &Invocation,
       PrebuiltCachePath, Invocation.getModuleName(), InputPath,
       Invocation.getOutputFilename(),
       FEOpts.SerializeModuleInterfaceDependencyHashes,
-      FEOpts.TrackSystemDeps);
+      FEOpts.TrackSystemDeps, FEOpts.RemarkOnRebuildFromModuleInterface);
 }
 
 static bool compileLLVMIR(CompilerInvocation &Invocation,

test/ParseableInterface/ModuleCache/RebuildRemarks/rebuild-transitive-import.swift

@@ -0,0 +1,24 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/Build)
+// RUN: %empty-directory(%t/ModuleCache)
+
+// 1. Create a module called InnerModule, and put its interface into the build dir.
+// RUN: echo 'public func inInnerModule() {}' | %target-swift-frontend - -typecheck -emit-module-interface-path %t/Build/InnerModule.swiftinterface -enable-library-evolution -swift-version 5 -module-name InnerModule
+
+// 2. Build the .swiftinterface to a .swiftmodule, which will have a dependency on the interface
+// RUN: %target-swift-frontend -compile-module-from-interface -o %t/Build/InnerModule.swiftmodule %t/Build/InnerModule.swiftinterface
+
+// 3. Touch the interface so the module becomes out of date.
+// RUN: touch %t/Build/InnerModule.swiftinterface
+
+// 4. Create a module called OuterModule that imports InnerModule, and put its interface into the build dir.
+// RUN: echo 'import InnerModule' | %target-swift-frontend - -emit-module -o %t/Build/OuterModule.swiftmodule -module-name OuterModule -I %t/Build
+
+// 5. Build this file, and expect that InnerModule is out of date
+// RUN: %target-swift-frontend -typecheck %s -I %t/Build -Rmodule-interface-rebuild -module-cache-path %t/ModuleCache 2>&1 | %FileCheck %s
+
+import OuterModule
+
+// CHECK: rebuilding module 'InnerModule' from interface '{{.*}}/Build/InnerModule.swiftinterface'
+// CHECK: compiled module is out of date: '{{.*}}/Build/InnerModule.swiftmodule'
+// CHECK: dependency is out of date: '{{.*}}/Build/InnerModule.swiftinterface'