[Dependency Scanning] Break out Swift overlay dependencies into separate output category

Instead of being a part of 'directDependencies' on a module dependency info, make them a separate array of dependency IDs for Swift Source and Textual modules.

This will allow clients to still distinguish direct module dependencies imported from a given module, versus dependencies added because direct/transitive Clang module dependencies have Swift overlays.

This change does *not* remove overlay dependencies from 'directDependencies' yet, just adds them as a separate field on the module details info. A followup change will remove overlay and bridging header dependencies from 'directDependencies' once the clients have had a chance to adopt to this change.

Author: artemcm

include/swift-c/DependencyScan/DependencyScan.h

@@ -150,6 +150,10 @@ swiftscan_swift_textual_detail_get_context_hash(
 SWIFTSCAN_PUBLIC bool swiftscan_swift_textual_detail_get_is_framework(
     swiftscan_module_details_t details);
 
+SWIFTSCAN_PUBLIC swiftscan_string_set_t *
+swiftscan_swift_textual_detail_get_swift_overlay_dependencies(
+    swiftscan_module_details_t details);
+
 //=== Swift Binary Module Details query APIs ------------------------------===//
 
 SWIFTSCAN_PUBLIC swiftscan_string_ref_t

include/swift/AST/ModuleDependencies.h

@@ -137,6 +137,10 @@ struct CommonSwiftTextualModuleDependencyDetails {
 
   /// (Clang) modules on which the bridging header depends.
   std::vector<std::string> bridgingModuleDependencies;
+
+  /// Dependencies comprised of Swift overlay modules of direct and
+  /// transitive Clang dependencies.
+  std::vector<ModuleDependencyID> swiftOverlayDependencies;
 };
 
 /// Describes the dependencies of a Swift module described by an Swift interface file.
@@ -450,12 +454,26 @@ class ModuleDependencyInfo {
   }
 
   /// Resolve a dependency's set of `imports` with qualified Module IDs
-  void resolveDependencies(const std::vector<ModuleDependencyID> &dependencyIDs) {
+  void resolveDependencies(const ArrayRef<ModuleDependencyID> dependencyIDs) {
     assert(!storage->resolved && "Resolving an already-resolved dependency");
     storage->resolved = true;
     storage->resolvedModuleDependencies.assign(dependencyIDs.begin(), dependencyIDs.end());
   }
 
+  /// Set this module's set of Swift Overlay dependencies
+  void setOverlayDependencies(const ArrayRef<ModuleDependencyID> dependencyIDs) {
+    assert(isSwiftSourceModule() || isSwiftInterfaceModule());
+    CommonSwiftTextualModuleDependencyDetails *textualModuleDetails;
+    if (auto sourceDetailsStorage = dyn_cast<SwiftSourceModuleDependenciesStorage>(storage.get())) {
+      textualModuleDetails = &sourceDetailsStorage->textualModuleDetails;
+    } else if (auto interfaceDetailsStorage = dyn_cast<SwiftInterfaceModuleDependenciesStorage>(storage.get())) {
+      textualModuleDetails = &interfaceDetailsStorage->textualModuleDetails;
+    } else {
+      llvm_unreachable("Unknown kind of dependency module info.");
+    }
+    textualModuleDetails->swiftOverlayDependencies.assign(dependencyIDs.begin(), dependencyIDs.end());
+  }
+
   void updateCommandLine(const std::vector<std::string> &newCommandLine) {
     assert(isSwiftInterfaceModule() && "Can only update command line on Swift interface dependency");
     cast<SwiftInterfaceModuleDependenciesStorage>(storage.get())->updateCommandLine(newCommandLine);
@@ -762,7 +780,12 @@ class ModuleDependenciesCache {
   /// Resolve a dependency module's set of imports
   /// to a kind-qualified set of module IDs.
   void resolveDependencyImports(ModuleDependencyID moduleID,
-                                const std::vector<ModuleDependencyID> &dependencyIDs);
+                                const ArrayRef<ModuleDependencyID> dependencyIDs);
+
+  /// Resolve a dependency module's set of Swift module dependencies
+  /// that are Swift overlays of Clang module dependencies.
+  void setSwiftOverlayDependencues(ModuleDependencyID moduleID,
+                                   const ArrayRef<ModuleDependencyID> dependencyIDs);
 
   StringRef getMainModuleName() const {
     return mainScanModuleName;

include/swift/DependencyScan/DependencyScanImpl.h

@@ -79,6 +79,10 @@ typedef struct {
   /// (Clang) modules on which the bridging header depends.
   swiftscan_string_set_t *bridging_module_dependencies;
 
+  /// (Swift) module dependencies by means of being overlays of
+  /// Clang module dependencies
+  swiftscan_string_set_t *swift_overlay_module_dependencies;
+
   /// Options to the compile command required to build this module interface
   swiftscan_string_set_t *command_line;
 

include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h

@@ -41,7 +41,7 @@ using llvm::BCVBR;
 const unsigned char MODULE_DEPENDENCY_CACHE_FORMAT_SIGNATURE[] = {'I', 'M', 'D','C'};
 const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MAJOR = 4;
 /// Increment this on every change.
-const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MINOR = 0;
+const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MINOR = 1;
 
 /// Various identifiers in this format will rely on having their strings mapped
 /// using this ID.
@@ -139,7 +139,8 @@ using SwiftInterfaceModuleDetailsLayout =
                    FileIDField,                         // bridgingHeaderFile
                    FileIDArrayIDField,                  // sourceFiles
                    FileIDArrayIDField,                  // bridgingSourceFiles
-                   FileIDArrayIDField                   // bridgingModuleDependencies
+                   FileIDArrayIDField,                  // bridgingModuleDependencies
+                   DependencyIDArrayIDField             // swiftOverlayDependencies
                    >;
 
 using SwiftSourceModuleDetailsLayout =
@@ -148,7 +149,8 @@ using SwiftSourceModuleDetailsLayout =
                    FileIDField,                      // bridgingHeaderFile
                    FileIDArrayIDField,               // sourceFiles
                    FileIDArrayIDField,               // bridgingSourceFiles
-                   FileIDArrayIDField                // bridgingModuleDependencies
+                   FileIDArrayIDField,               // bridgingModuleDependencies
+                   DependencyIDArrayIDField          // swiftOverlayDependencies
                    >;
 
 using SwiftBinaryModuleDetailsLayout =

include/swift/Option/Options.td

@@ -1286,6 +1286,10 @@ def disable_clang_target : Flag<["-"], "disable-clang-target">,
   Flags<[NewDriverOnlyOption]>,
   HelpText<"Disable a separately specified target triple for Clang instance to use">;
 
+def explain_module_dependency : Separate<["-"], "explain-module-dependency">,
+  Flags<[NewDriverOnlyOption]>,
+  HelpText<"Emit remark/notes describing why compilaiton may depend on a module with a given name.">;
+
 def min_inlining_target_version : Separate<["-"], "target-min-inlining-version">,
   Flags<[FrontendOption, ModuleInterfaceOptionIgnorable]>,
   HelpText<"Require inlinable code with no '@available' attribute to back-deploy "

lib/AST/ModuleDependencies.cpp

@@ -447,11 +447,21 @@ void ModuleDependenciesCache::updateDependency(
 }
 
 void ModuleDependenciesCache::resolveDependencyImports(ModuleDependencyID moduleID,
-                                                       const std::vector<ModuleDependencyID> &dependencyIDs) {
+                                                       const ArrayRef<ModuleDependencyID> dependencyIDs) {
   auto optionalDependencyInfo = findDependency(moduleID.first, moduleID.second);
   assert(optionalDependencyInfo.has_value() && "Resolving unknown dependency");
   // Copy the existing info to a mutable one we can then replace it with, after resolving its dependencies.
   auto dependencyInfo = *(optionalDependencyInfo.value());
   dependencyInfo.resolveDependencies(dependencyIDs);
   updateDependency(moduleID, dependencyInfo);
 }
+
+void ModuleDependenciesCache::setSwiftOverlayDependencues(ModuleDependencyID moduleID,
+                                                          const ArrayRef<ModuleDependencyID> dependencyIDs) {
+  auto optionalDependencyInfo = findDependency(moduleID.first, moduleID.second);
+  assert(optionalDependencyInfo.has_value() && "Resolving unknown dependency");
+  // Copy the existing info to a mutable one we can then replace it with, after setting its overlay dependencies.
+  auto dependencyInfo = *(optionalDependencyInfo.value());
+  dependencyInfo.setOverlayDependencies(dependencyIDs);
+  updateDependency(moduleID, dependencyInfo);
+}