[frontend] Introduce a new frontend option '-dump-api-path', which ou…

…tputs a swift interface file for each compiled source file.

This is primarily intended for use with the stdlib.

include/swift/Frontend/FrontendOptions.h

@@ -122,6 +122,9 @@ class FrontendOptions {
   /// should only be used for debugging and experimental features.
   std::vector<std::string> LLVMArgs;
 
+  /// The path to output swift interface files for the compiled source files.
+  std::string DumpAPIPath;
+
   enum ActionType {
     NoneAction, ///< No specific action
     Parse, ///< Parse and type-check only

include/swift/Option/FrontendOptions.td

@@ -280,6 +280,9 @@ def dump_interface_hash : Flag<["-"], "dump-interface-hash">,
    HelpText<"Parse input file(s) and dump interface token hash(es)">,
    ModeOpt;
 
+def dump_api_path : Separate<["-"], "dump-api-path">,
+  HelpText<"The path to output swift interface files for the compiled source files">;
+
 def enable_resilience : Flag<["-"], "enable-resilience">,
    HelpText<"Treat all types as resilient by default">;
 

lib/AST/Decl.cpp

@@ -394,7 +394,8 @@ bool Decl::isPrivateStdlibDecl(bool whitelistProtocols) const {
   if (!FU)
     return false;
   // Check for Swift module and overlays.
-  if (FU->getKind() != FileUnitKind::SerializedAST)
+  if (!DC->getParentModule()->isStdlibModule() &&
+      FU->getKind() != FileUnitKind::SerializedAST)
     return false;
 
   auto hasInternalParameter = [](ArrayRef<const Pattern *> Pats) -> bool {
@@ -436,6 +437,11 @@ bool Decl::isPrivateStdlibDecl(bool whitelistProtocols) const {
       return false;
   }
 
+  if (auto ImportD = dyn_cast<ImportDecl>(D)) {
+    if (ImportD->getModule()->isSwiftShimsModule())
+      return true;
+  }
+
   auto VD = dyn_cast<ValueDecl>(D);
   if (!VD || !VD->hasName())
     return false;

lib/Frontend/CompilerInvocation.cpp

@@ -111,6 +111,10 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
     }
   }
 
+  if (const Arg *A = Args.getLastArg(OPT_dump_api_path)) {
+    Opts.DumpAPIPath = A->getValue();
+  }
+
   Opts.EmitVerboseSIL |= Args.hasArg(OPT_emit_verbose_sil);
   Opts.EmitSortedSIL |= Args.hasArg(OPT_emit_sorted_sil);
 
@@ -650,6 +654,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
                           DiagnosticEngine &Diags, bool isImmediate) {
   using namespace options;
 
+  Opts.AttachCommentsToDecls |= Args.hasArg(OPT_dump_api_path);
+
   Opts.UseMalloc |= Args.hasArg(OPT_use_malloc);
 
   Opts.EnableExperimentalPatterns |=

tools/driver/frontend_main.cpp

@@ -55,6 +55,7 @@
 #include "llvm/Support/YAMLParser.h"
 
 #include <memory>
+#include <unordered_set>
 
 using namespace swift;
 
@@ -921,6 +922,68 @@ static bool performCompile(CompilerInstance &Instance,
   return false;
 }
 
+/// Returns true if an error occurred.
+static bool dumpAPI(Module *Mod, StringRef OutDir) {
+  using namespace llvm::sys;
+
+  auto getOutPath = [&](SourceFile *SF) -> std::string {
+    SmallString<256> Path = OutDir;
+    StringRef Filename = SF->getFilename();
+    path::append(Path, path::filename(Filename));
+    return Path.str();
+  };
+
+  std::unordered_set<std::string> Filenames;
+
+  auto dumpFile = [&](SourceFile *SF) -> bool {
+    SmallString<512> TempBuf;
+    llvm::raw_svector_ostream TempOS(TempBuf);
+
+    PrintOptions PO = PrintOptions::printInterface();
+    PO.PrintOriginalSourceText = true;
+    PO.Indent = 2;
+    PO.PrintAccessibility = false;
+    PO.SkipUnderscoredStdlibProtocols = true;
+    SF->print(TempOS, PO);
+    if (TempOS.str().trim().empty())
+      return false; // nothing to show.
+
+    std::string OutPath = getOutPath(SF);
+    bool WasInserted = Filenames.insert(OutPath).second;
+    if (!WasInserted) {
+      llvm::errs() << "multiple source files ended up with the same dump API "
+                      "filename to write to: " << OutPath << '\n';
+      return true;
+    }
+
+    std::error_code EC;
+    llvm::raw_fd_ostream OS(OutPath, EC, fs::OpenFlags::F_RW);
+    if (EC) {
+      llvm::errs() << "error opening file '" << OutPath << "': "
+                   << EC.message() << '\n';
+      return true;
+    }
+
+    OS << TempOS.str();
+    return false;
+  };
+
+  std::error_code EC = fs::create_directories(OutDir);
+  if (EC) {
+    llvm::errs() << "error creating directory '" << OutDir << "': "
+                 << EC.message() << '\n';
+    return true;
+  }
+
+  for (auto *FU : Mod->getFiles()) {
+    if (SourceFile *SF = dyn_cast<SourceFile>(FU))
+      if (dumpFile(SF))
+        return true;
+  }
+
+  return false;
+}
+
 int frontend_main(ArrayRef<const char *>Args,
                   const char *Argv0, void *MainAddr) {
   llvm::InitializeAllTargets();
@@ -1045,6 +1108,11 @@ int frontend_main(ArrayRef<const char *>Args,
   bool HadError = performCompile(Instance, Invocation, Args, ReturnValue) ||
                   Instance.getASTContext().hadError();
 
+  if (!HadError && !Invocation.getFrontendOptions().DumpAPIPath.empty()) {
+    HadError = dumpAPI(Instance.getMainModule(),
+                       Invocation.getFrontendOptions().DumpAPIPath);
+  }
+
   if (Invocation.getDiagnosticOptions().VerifyDiagnostics) {
     HadError = verifyDiagnostics(Instance.getSourceMgr(),
                                  Instance.getInputBufferIDs());