Merge remote-tracking branch 'origin/master' into master-next

include/swift/AST/DiagnosticsFrontend.def

@@ -106,6 +106,8 @@ ERROR(error_mode_cannot_emit_dependencies,none,
   "this mode does not support emitting dependency files", ())
 ERROR(error_mode_cannot_emit_header,none,
   "this mode does not support emitting Objective-C headers", ())
+ERROR(error_mode_cannot_emit_loaded_module_trace,none,
+  "this mode does not support emitting the loaded module trace", ())
 ERROR(error_mode_cannot_emit_module,none,
   "this mode does not support emitting modules", ())
 ERROR(error_mode_cannot_emit_module_doc,none,

include/swift/AST/ProtocolConformance.h

@@ -473,8 +473,11 @@ public:
   /// Determine whether the witness for the given type requirement
   /// is the default definition.
   bool usesDefaultDefinition(AssociatedTypeDecl *requirement) const {
-    return getTypeWitnessAndDecl(requirement, nullptr)
-        .second->isImplicit();
+    TypeDecl *witnessDecl = getTypeWitnessAndDecl(requirement, nullptr).second;
+    if (witnessDecl)
+      return witnessDecl->isImplicit();
+    // Conservatively assume it does not.
+    return false;
   }
 
   void setLazyLoader(LazyMemberLoader *resolver, uint64_t contextData);

include/swift/Basic/JSONSerialization.h

@@ -445,6 +445,16 @@ private:
   void indent();
 };
 
+template <typename T> struct ArrayTraits<std::vector<T>> {
+  static size_t size(Output &out, std::vector<T> &seq) { return seq.size(); }
+
+  static T &element(Output &out, std::vector<T> &seq, size_t index) {
+    if (index >= seq.size())
+      seq.resize(index + 1);
+    return seq[index];
+  }
+};
+
 template<>
 struct ScalarTraits<bool> {
   static void output(const bool &, llvm::raw_ostream &);

include/swift/Driver/Compilation.h

@@ -146,6 +146,10 @@ private:
   /// detail than ShowIncrementalBuildDecisions.
   bool ShowJobLifecycle = false;
 
+  /// When true, some frontend job has requested permission to pass
+  /// -emit-loaded-module-trace, so no other job needs to do it.
+  bool PassedEmitLoadedModuleTraceToFrontendJob = false;
+
   static const Job *unwrap(const std::unique_ptr<const Job> &p) {
     return p.get();
   }
@@ -232,6 +236,22 @@ public:
   /// -2 indicates that one of the Compilation's Jobs crashed during execution
   int performJobs();
 
+  /// Returns whether the callee is permitted to pass -emit-loaded-module-trace
+  /// to a frontend job.
+  ///
+  /// This only returns true once, because only one job should pass that
+  /// argument.
+  bool requestPermissionForFrontendToEmitLoadedModuleTrace() {
+    if (PassedEmitLoadedModuleTraceToFrontendJob)
+      // Someone else has already done it!
+      return false;
+    else {
+      // We're the first and only (to execute this path).
+      PassedEmitLoadedModuleTraceToFrontendJob = true;
+      return true;
+    }
+  }
+
 private:
   /// \brief Perform all jobs.
   ///

include/swift/Driver/Types.def

@@ -59,6 +59,7 @@ TYPE("swift-dependencies", SwiftDeps,       "swiftdeps",       "")
 TYPE("remap",           Remapping,          "remap",           "")
 TYPE("imported-modules", ImportedModules,   "importedmodules", "")
 TYPE("tbd",             TBD,                "tbd",             "")
+TYPE("module-trace",    ModuleTrace,        "trace.json",      "")
 
 // Misc types
 TYPE("pcm",             ClangModuleFile,    "pcm",             "")

include/swift/Frontend/FrontendOptions.h

@@ -116,6 +116,9 @@ public:
   /// The path to which we should output fixits as source edits.
   std::string FixitsOutputPath;
 
+  /// The path to which we should output a loaded module trace file.
+  std::string LoadedModuleTracePath;
+
   /// Arguments which should be passed in immediate mode.
   std::vector<std::string> ImmediateArgv;
 

include/swift/Option/Options.td

@@ -199,6 +199,16 @@ def emit_dependencies : Flag<["-"], "emit-dependencies">,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>,
   HelpText<"Emit basic Make-compatible dependencies files">;
 
+def emit_loaded_module_trace : Flag<["-"], "emit-loaded-module-trace">,
+  Flags<[FrontendOption, NoInteractiveOption]>,
+  HelpText<"Emit a JSON file containing information about what modules were loaded">;
+def emit_loaded_module_trace_path : Separate<["-"], "emit-loaded-module-trace-path">,
+  Flags<[FrontendOption, NoInteractiveOption]>,
+  HelpText<"Emit the loaded module trace JSON to <path>">,
+  MetaVarName<"<path>">;
+def emit_loaded_module_trace_path_EQ : Joined<["-"], "emit-loaded-module-trace-path=">,
+  Flags<[FrontendOption, NoInteractiveOption]>, Alias<emit_loaded_module_trace_path>;
+
 def serialize_diagnostics : Flag<["-"], "serialize-diagnostics">,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>,
   HelpText<"Serialize diagnostics in a binary format">;

include/swift/Serialization/ModuleFormat.h

@@ -54,7 +54,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// in source control, you should also update the comment to briefly
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
-const uint16_t VERSION_MINOR = 335; // Last change: no type in objc method table
+const uint16_t VERSION_MINOR = 336; // Last change: typealias canonical type
 
 using DeclID = PointerEmbeddedInt<unsigned, 31>;
 using DeclIDField = BCFixed<31>;
@@ -571,7 +571,8 @@ namespace decls_block {
 
   using NameAliasTypeLayout = BCRecordLayout<
     NAME_ALIAS_TYPE,
-    DeclIDField // typealias decl
+    DeclIDField, // typealias decl
+    TypeIDField  // canonical type (a fallback)
   >;
 
   using GenericTypeParamTypeLayout = BCRecordLayout<