[Dependency Scanning] Model main module as separate dependency kind: SwiftSource

These kinds of modules differ from `SwiftTextual` modules in that they do not have an interface and have source-files.
It is cleaner to enforce this distinction with types, instead of checking for interface optionality everywhere.

Author: artemcm

include/swift-c/DependencyScan/DependencyScan.h

@@ -49,6 +49,8 @@ typedef struct {
 } swiftscan_string_set_t;
 
 typedef enum {
+  // This dependency info encodes two ModuleDependencyKind types:
+  // SwiftInterface and SwiftSource.
   SWIFTSCAN_DEPENDENCY_INFO_SWIFT_TEXTUAL = 0,
   SWIFTSCAN_DEPENDENCY_INFO_SWIFT_BINARY = 1,
   SWIFTSCAN_DEPENDENCY_INFO_SWIFT_PLACEHOLDER = 2,

include/swift/AST/ModuleDependencies.h

@@ -37,7 +37,8 @@ class Identifier;
 /// Which kind of module dependencies we are looking for.
 enum class ModuleDependenciesKind : int8_t {
   FirstKind,
-  SwiftTextual = FirstKind,
+  SwiftInterface = FirstKind,
+  SwiftSource,
   SwiftBinary,
   // Placeholder dependencies are a kind of dependencies used only by the
   // dependency scanner. They are swift modules that the scanner will not be
@@ -97,14 +98,14 @@ class ModuleDependenciesStorageBase {
   std::vector<std::string> moduleDependencies;
 };
 
-/// Describes the dependencies of a Swift module.
+/// Describes the dependencies of a Swift module described by an Swift interface file.
 ///
 /// This class is mostly an implementation detail for \c ModuleDependencies.
-class SwiftTextualModuleDependenciesStorage :
+class SwiftInterfaceModuleDependenciesStorage :
   public ModuleDependenciesStorageBase {
 public:
-  /// The Swift interface file, if it can be used to generate the module file.
-  const Optional<std::string> swiftInterfaceFile;
+  /// The Swift interface file to be used to generate the module file.
+  const std::string swiftInterfaceFile;
 
   /// Potentially ready-to-use compiled modules for the interface file.
   const std::vector<std::string> compiledModuleCandidates;
@@ -136,14 +137,14 @@ class SwiftTextualModuleDependenciesStorage :
   /// (Clang) modules on which the bridging header depends.
   std::vector<std::string> bridgingModuleDependencies;
 
-  SwiftTextualModuleDependenciesStorage(
-      const Optional<std::string> &swiftInterfaceFile,
+  SwiftInterfaceModuleDependenciesStorage(
+      const std::string swiftInterfaceFile,
       ArrayRef<std::string> compiledModuleCandidates,
       ArrayRef<StringRef> buildCommandLine,
       ArrayRef<StringRef> extraPCMArgs,
       StringRef contextHash,
       bool isFramework
-  ) : ModuleDependenciesStorageBase(ModuleDependenciesKind::SwiftTextual),
+  ) : ModuleDependenciesStorageBase(ModuleDependenciesKind::SwiftInterface),
       swiftInterfaceFile(swiftInterfaceFile),
       compiledModuleCandidates(compiledModuleCandidates.begin(),
                                compiledModuleCandidates.end()),
@@ -152,14 +153,51 @@ class SwiftTextualModuleDependenciesStorage :
       contextHash(contextHash), isFramework(isFramework) { }
 
   ModuleDependenciesStorageBase *clone() const override {
-    return new SwiftTextualModuleDependenciesStorage(*this);
+    return new SwiftInterfaceModuleDependenciesStorage(*this);
   }
 
   static bool classof(const ModuleDependenciesStorageBase *base) {
-    return base->dependencyKind == ModuleDependenciesKind::SwiftTextual;
+    return base->dependencyKind == ModuleDependenciesKind::SwiftInterface;
   }
 };
 
+/// Describes the dependencies of a Swift module
+///
+/// This class is mostly an implementation detail for \c ModuleDependencies.
+class SwiftSourceModuleDependenciesStorage :
+  public ModuleDependenciesStorageBase {
+public:
+  /// To build a PCM to be used by this Swift module, we need to append these
+  /// arguments to the generic PCM build arguments reported from the dependency
+  /// graph.
+  const std::vector<std::string> extraPCMArgs;
+
+  /// Bridging header file, if there is one.
+  Optional<std::string> bridgingHeaderFile;
+
+  /// Swift source files that are part of the Swift module, when known.
+  std::vector<std::string> sourceFiles;
+
+  /// Source files on which the bridging header depends.
+  std::vector<std::string> bridgingSourceFiles;
+
+  /// (Clang) modules on which the bridging header depends.
+  std::vector<std::string> bridgingModuleDependencies;
+
+    SwiftSourceModuleDependenciesStorage(
+      ArrayRef<StringRef> extraPCMArgs
+    ) : ModuleDependenciesStorageBase(ModuleDependenciesKind::SwiftSource),
+        extraPCMArgs(extraPCMArgs.begin(), extraPCMArgs.end()) {}
+
+    ModuleDependenciesStorageBase *clone() const override {
+      return new SwiftSourceModuleDependenciesStorage(*this);
+    }
+
+    static bool classof(const ModuleDependenciesStorageBase *base) {
+      return base->dependencyKind == ModuleDependenciesKind::SwiftSource;
+    }
+  };
+
 /// Describes the dependencies of a pre-built Swift module (with no .swiftinterface).
 ///
 /// This class is mostly an implementation detail for \c ModuleDependencies.
@@ -291,15 +329,15 @@ class ModuleDependencies {
 
   /// Describe the module dependencies for a Swift module that can be
   /// built from a Swift interface file (\c .swiftinterface).
-  static ModuleDependencies forSwiftTextualModule(
-      const Optional<std::string> &swiftInterfaceFile,
+  static ModuleDependencies forSwiftInterfaceModule(
+      std::string swiftInterfaceFile,
       ArrayRef<std::string> compiledCandidates,
       ArrayRef<StringRef> buildCommands,
       ArrayRef<StringRef> extraPCMArgs,
       StringRef contextHash,
       bool isFramework) {
     return ModuleDependencies(
-        std::make_unique<SwiftTextualModuleDependenciesStorage>(
+        std::make_unique<SwiftInterfaceModuleDependenciesStorage>(
           swiftInterfaceFile, compiledCandidates, buildCommands,
           extraPCMArgs, contextHash, isFramework));
   }
@@ -316,11 +354,9 @@ class ModuleDependencies {
   }
 
   /// Describe the main Swift module.
-  static ModuleDependencies forMainSwiftModule(ArrayRef<StringRef> extraPCMArgs) {
+  static ModuleDependencies forSwiftSourceModule(ArrayRef<StringRef> extraPCMArgs) {
     return ModuleDependencies(
-        std::make_unique<SwiftTextualModuleDependenciesStorage>(
-          None, ArrayRef<std::string>(), ArrayRef<StringRef>(),
-          extraPCMArgs, StringRef(), false));
+        std::make_unique<SwiftSourceModuleDependenciesStorage>(extraPCMArgs));
   }
 
   /// Describe the module dependencies for a Clang module that can be
@@ -350,11 +386,14 @@ class ModuleDependencies {
     return storage->moduleDependencies;
   }
 
-  /// Whether the dependencies are for a Swift module: either Textual, Binary, or Placeholder.
+  /// Whether the dependencies are for a Swift module: either Textual, Source, Binary, or Placeholder.
   bool isSwiftModule() const;
 
   /// Whether the dependencies are for a textual Swift module.
-  bool isSwiftTextualModule() const;
+  bool isSwiftInterfaceModule() const;
+
+  /// Whether the dependencies are for a textual Swift module.
+  bool isSwiftSourceModule() const;
 
   /// Whether the dependencies are for a binary Swift module.
   bool isSwiftBinaryModule() const;
@@ -368,8 +407,11 @@ class ModuleDependencies {
   ModuleDependenciesKind getKind() const {
     return storage->dependencyKind;
   }
+  /// Retrieve the dependencies for a Swift textual-interface module.
+  const SwiftInterfaceModuleDependenciesStorage *getAsSwiftInterfaceModule() const;
+
   /// Retrieve the dependencies for a Swift module.
-  const SwiftTextualModuleDependenciesStorage *getAsSwiftTextualModule() const;
+  const SwiftSourceModuleDependenciesStorage *getAsSwiftSourceModule() const;
 
   /// Retrieve the dependencies for a binary Swift module.
   const SwiftBinaryModuleDependencyStorage *getAsSwiftBinaryModule() const;

include/swift/ClangImporter/ClangImporter.h

@@ -409,7 +409,9 @@ class ClangImporter final : public ClangModuleLoader {
   ///
   /// \returns \c true if an error occurred, \c false otherwise
   bool addBridgingHeaderDependencies(
-      StringRef moduleName, ModuleDependenciesCache &cache);
+      StringRef moduleName,
+      ModuleDependenciesKind moduleKind,
+      ModuleDependenciesCache &cache);
 
   clang::TargetInfo &getTargetInfo() const override;
   clang::ASTContext &getClangASTContext() const override;

include/swift/DependencyScan/DependencyScanImpl.h

@@ -37,7 +37,8 @@ struct swiftscan_dependency_info_s {
   /// The format is:
   /// `<module-kind>:<module-name>`
   /// where `module-kind` is one of:
-  /// "swiftTextual"
+  /// "swiftInterface"
+  /// "swiftSource"
   /// "swiftBinary"
   /// "swiftPlaceholder"
   /// "clang""

include/swift/DependencyScan/DependencyScanningTool.h

@@ -66,6 +66,11 @@ class DependencyScanningTool {
   void resetCache();
 
 private:
+  /// Using the specified invocation command, initialize the scanner instance
+  /// for this scan. Returns the `CompilerInstance` that will be used.
+  llvm::ErrorOr<std::unique_ptr<CompilerInstance>>
+  initScannerForAction(ArrayRef<const char *> Command);
+
   /// Using the specified invocation command, instantiate a CompilerInstance
   /// that will be used for this scan.
   llvm::ErrorOr<std::unique_ptr<CompilerInstance>>

include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h

@@ -37,7 +37,7 @@ using llvm::BCVBR;
 /// Every .moddepcache file begins with these 4 bytes, for easy identification.
 const unsigned char MODULE_DEPENDENCY_CACHE_FORMAT_SIGNATURE[] = {'I', 'M', 'D',
                                                                   'C'};
-const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MAJOR = 1;
+const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MAJOR = 2;
 /// Increment this on every change.
 const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MINOR = 0;
 
@@ -72,7 +72,8 @@ namespace graph_block {
 enum {
   METADATA = 1,
   MODULE_NODE,
-  SWIFT_TEXTUAL_MODULE_DETAILS_NODE,
+  SWIFT_INTERFACE_MODULE_DETAILS_NODE,
+  SWIFT_SOURCE_MODULE_DETAILS_NODE,
   SWIFT_PLACEHOLDER_MODULE_DETAILS_NODE,
   SWIFT_BINARY_MODULE_DETAILS_NODE,
   CLANG_MODULE_DETAILS_NODE,
@@ -109,7 +110,8 @@ using IdentifierArrayLayout =
 
 // After the array records, we have a sequence of Module info
 // records, each of which is followed by one of:
-// - SwiftTextualModuleDetails
+// - SwiftInterfaceModuleDetails
+// - SwiftSourceModuleDetails
 // - SwiftBinaryModuleDetails
 // - SwiftPlaceholderModuleDetails
 // - ClangModuleDetails
@@ -119,8 +121,8 @@ using ModuleInfoLayout =
                    DependencyIDArrayIDField // directDependencies
                    >;
 
-using SwiftTextualModuleDetailsLayout =
-    BCRecordLayout<SWIFT_TEXTUAL_MODULE_DETAILS_NODE, // ID
+using SwiftInterfaceModuleDetailsLayout =
+    BCRecordLayout<SWIFT_INTERFACE_MODULE_DETAILS_NODE, // ID
                    FileIDField,                       // swiftInterfaceFile
                    FileIDArrayIDField, // compiledModuleCandidates
                    FlagIDArrayIDField, // buildCommandLine
@@ -130,7 +132,16 @@ using SwiftTextualModuleDetailsLayout =
                    FileIDField,        // bridgingHeaderFile
                    FileIDArrayIDField, // sourceFiles
                    FileIDArrayIDField, // bridgingSourceFiles
-                   IdentifierIDField   // bridgingModuleDependencies
+                   FileIDArrayIDField   // bridgingModuleDependencies
+                   >;
+
+using SwiftSourceModuleDetailsLayout =
+    BCRecordLayout<SWIFT_SOURCE_MODULE_DETAILS_NODE, // ID
+                   FlagIDArrayIDField, // extraPCMArgs
+                   FileIDField,        // bridgingHeaderFile
+                   FileIDArrayIDField, // sourceFiles
+                   FileIDArrayIDField, // bridgingSourceFiles
+                   FileIDArrayIDField  // bridgingModuleDependencies
                    >;
 
 using SwiftBinaryModuleDetailsLayout =

include/swift/DependencyScan/StringUtils.h

@@ -35,6 +35,9 @@ swiftscan_string_set_t *create_set(const std::vector<std::string> &strings);
 /// create_clone routine.
 swiftscan_string_set_t *create_set(int count, const char **strings);
 
+/// Create an empty array of swiftscan_string_ref_t objects
+swiftscan_string_set_t *create_empty_set();
+
 /// Retrieve the character data associated with the given string.
 const char *get_C_string(swiftscan_string_ref_t string);
 }

lib/AST/ASTContext.cpp

@@ -1579,7 +1579,11 @@ Optional<ModuleDependencies> ASTContext::getModuleDependencies(
     if (!isUnderlyingClangModule) {
       if (auto found = cache.findDependencies(
               moduleName,
-              {ModuleDependenciesKind::SwiftTextual, searchPathSet}))
+              {ModuleDependenciesKind::SwiftSource, searchPathSet}))
+        return found;
+      if (auto found = cache.findDependencies(
+              moduleName,
+              {ModuleDependenciesKind::SwiftInterface, searchPathSet}))
         return found;
       if (auto found = cache.findDependencies(
               moduleName, {ModuleDependenciesKind::SwiftBinary, searchPathSet}))