[Glibc] Use VFS to inject modulemap into Glibc include path

include/swift/AST/DiagnosticsClangImporter.def

@@ -117,6 +117,9 @@ WARNING(nonmutating_without_mutable_fields,none,
 
 ERROR(module_map_not_found, none, "module map file '%0' not found", (StringRef))
 
+WARNING(glibc_not_found, none,
+        "glibc not found for '%0'; C stdlib may be unavailable",
+        (StringRef))
 WARNING(libstdcxx_not_found, none,
         "libstdc++ not found for '%0'; C++ stdlib may be unavailable",
         (StringRef))

lib/ClangImporter/ClangImporter.cpp

@@ -648,13 +648,6 @@ importer::getNormalInvocationArguments(
         break;
       }
     }
-
-    SmallString<128> buffer;
-    if (auto path = getGlibcModuleMapPath(searchPathOpts, triple, buffer)) {
-      invocationArgStrs.push_back((Twine("-fmodule-map-file=") + *path).str());
-    } else {
-      // FIXME: Emit a warning of some kind.
-    }
   }
 
   if (searchPathOpts.getSDKPath().empty()) {

lib/ClangImporter/ClangIncludePaths.cpp

@@ -16,84 +16,143 @@
 #include "swift/AST/DiagnosticsClangImporter.h"
 #include "swift/Basic/Platform.h"
 #include "clang/Driver/Driver.h"
+#include "clang/Driver/ToolChain.h"
 #include "clang/Frontend/CompilerInstance.h"
 
 using namespace swift;
 
-static Optional<StringRef> getModuleMapFilePath(StringRef name,
-                                                SearchPathOptions &Opts,
-                                                llvm::Triple triple,
-                                                SmallVectorImpl<char> &buffer) {
+using Path = SmallString<128>;
+
+static Optional<Path> getActualModuleMapPath(StringRef name,
+                                             SearchPathOptions &Opts,
+                                             const llvm::Triple &triple) {
   StringRef platform = swift::getPlatformNameForTriple(triple);
   StringRef arch = swift::getMajorArchitectureName(triple);
 
+  Path result;
+
   StringRef SDKPath = Opts.getSDKPath();
   if (!SDKPath.empty()) {
-    buffer.clear();
-    buffer.append(SDKPath.begin(), SDKPath.end());
-    llvm::sys::path::append(buffer, "usr", "lib", "swift");
-    llvm::sys::path::append(buffer, platform, arch, name);
+    result.append(SDKPath.begin(), SDKPath.end());
+    llvm::sys::path::append(result, "usr", "lib", "swift");
+    llvm::sys::path::append(result, platform, arch, name);
 
     // Only specify the module map if that file actually exists.  It may not;
     // for example in the case that `swiftc -target x86_64-unknown-linux-gnu
     // -emit-ir` is invoked using a Swift compiler not built for Linux targets.
-    if (llvm::sys::fs::exists(buffer))
-      return StringRef(buffer.data(), buffer.size());
+    if (llvm::sys::fs::exists(result))
+      return result;
   }
 
   if (!Opts.RuntimeResourcePath.empty()) {
-    buffer.clear();
-    buffer.append(Opts.RuntimeResourcePath.begin(),
+    result.clear();
+    result.append(Opts.RuntimeResourcePath.begin(),
                   Opts.RuntimeResourcePath.end());
-    llvm::sys::path::append(buffer, platform, arch, name);
+    llvm::sys::path::append(result, platform, arch, name);
 
     // Only specify the module map if that file actually exists.  It may not;
     // for example in the case that `swiftc -target x86_64-unknown-linux-gnu
     // -emit-ir` is invoked using a Swift compiler not built for Linux targets.
-    if (llvm::sys::fs::exists(buffer))
-      return StringRef(buffer.data(), buffer.size());
+    if (llvm::sys::fs::exists(result))
+      return result;
   }
 
   return None;
 }
 
-Optional<StringRef>
-swift::getGlibcModuleMapPath(SearchPathOptions &Opts, llvm::Triple triple,
-                             SmallVectorImpl<char> &buffer) {
-  return getModuleMapFilePath("glibc.modulemap", Opts, triple, buffer);
+/// Given an include path directory, returns a path to inject the module map to.
+/// If a module map already exists, returns `None`.
+static llvm::Optional<Path> getInjectedModuleMapPath(const Path &dir) {
+  Path legacyPath(dir);
+  llvm::sys::path::append(legacyPath, "module.map");
+  if (llvm::sys::fs::exists(legacyPath))
+    return None;
+
+  Path path(dir);
+  llvm::sys::path::append(path, "module.modulemap");
+  if (llvm::sys::fs::exists(path))
+    return None;
+
+  return path;
 }
 
-static Optional<StringRef>
-getLibStdCxxModuleMapPath(SearchPathOptions &opts, llvm::Triple triple,
-                          SmallVectorImpl<char> &buffer) {
-  return getModuleMapFilePath("libstdcxx.modulemap", opts, triple, buffer);
+/// Finds the glibc.modulemap file relative to the provided resource dir.
+///
+/// Note that the module map used for Glibc depends on the target we're
+/// compiling for, and is not included in the resource directory with the other
+/// implicit module maps. It's at {freebsd|linux}/{arch}/glibc.modulemap.
+static Optional<Path>
+getGlibcModuleMapPath(SearchPathOptions &Opts, const llvm::Triple &triple) {
+  return getActualModuleMapPath("glibc.modulemap", Opts, triple);
 }
 
-SmallVector<std::pair<std::string, std::string>, 16>
-swift::getClangInvocationFileMapping(ASTContext &ctx) {
-  using Path = SmallString<128>;
+static Optional<Path>
+getLibStdCxxModuleMapPath(SearchPathOptions &opts, const llvm::Triple &triple) {
+  return getActualModuleMapPath("libstdcxx.modulemap", opts, triple);
+}
 
-  const llvm::Triple &triple = ctx.LangOpts.Target;
-  // We currently only need this when building for Linux.
-  if (!triple.isOSLinux())
-    return {};
-  // Android uses libc++.
-  if (triple.isAndroid())
-    return {};
+static llvm::opt::InputArgList
+parseClangDriverArgs(const clang::driver::Driver &clangDriver,
+                     const ArrayRef<const char *> args) {
+  unsigned unused1, unused2;
+  return clangDriver.getOpts().ParseArgs(args, unused1, unused2);
+}
 
-  // Extract the libstdc++ installation path from Clang driver.
+static clang::driver::Driver createClangDriver(const ASTContext &ctx) {
   auto clangDiags = clang::CompilerInstance::createDiagnostics(
       new clang::DiagnosticOptions());
   clang::driver::Driver clangDriver(ctx.ClangImporterOpts.clangPath,
-                                    triple.str(), *clangDiags);
+                                    ctx.LangOpts.Target.str(), *clangDiags);
+  return clangDriver;
+}
+
+/// Given a list of include paths and a list of file names, finds the first
+/// include path that contains files with all the names. This is useful for
+/// finding the include path for a specific library among a list of include
+/// paths.
+///
+/// \return a path without dots (`../`, './').
+static llvm::Optional<Path>
+findFirstIncludeDir(const llvm::opt::InputArgList &args,
+                    const ArrayRef<const char *> expectedFileNames) {
+  // C++ stdlib paths are added as `-internal-isystem`.
+  std::vector<std::string> includeDirs =
+      args.getAllArgValues(clang::driver::options::OPT_internal_isystem);
+  // C stdlib paths are added as `-internal-externc-isystem`.
+  llvm::append_range(includeDirs,
+                     args.getAllArgValues(
+                         clang::driver::options::OPT_internal_externc_isystem));
+
+  for (const auto &includeDir : includeDirs) {
+    Path dir(includeDir);
+    bool allExpectedExist = true;
+    for (auto expectedFileName : expectedFileNames) {
+      Path expectedFile(dir);
+      llvm::sys::path::append(expectedFile, expectedFileName);
+      if (!llvm::sys::fs::exists(expectedFile)) {
+        allExpectedExist = false;
+        break;
+      }
+    }
+
+    if (allExpectedExist) {
+      // VFS does not allow mapping paths that contain `../` or `./`.
+      llvm::sys::path::remove_dots(dir, /*remove_dot_dot=*/true);
+      return dir;
+    }
+  }
+  return None;
+}
+
+static llvm::opt::InputArgList
+createClangArgs(const ASTContext &ctx, clang::driver::Driver &clangDriver) {
   // Flags passed to Swift with `-Xcc` might affect include paths.
-  unsigned unused1, unused2;
   std::vector<const char *> clangArgs;
   for (const auto &each : ctx.ClangImporterOpts.ExtraArgs) {
     clangArgs.push_back(each.c_str());
   }
   llvm::opt::InputArgList clangDriverArgs =
-      clangDriver.getOpts().ParseArgs(clangArgs, unused1, unused2);
+      parseClangDriverArgs(clangDriver, clangArgs);
   // If an SDK path was explicitly passed to Swift, make sure to pass it to
   // Clang driver as well. It affects the resulting include paths.
   auto sdkPath = ctx.SearchPathOpts.getSDKPath();
@@ -103,23 +162,106 @@ swift::getClangInvocationFileMapping(ASTContext &ctx) {
         clangDriver.getOpts().getOption(clang::driver::options::OPT__sysroot),
         sdkPath, argIndex));
   }
-  auto cxxStdlibDirs =
-      clangDriver.getLibStdCxxIncludePaths(clangDriverArgs, triple);
-  if (cxxStdlibDirs.empty()) {
-    ctx.Diags.diagnose(SourceLoc(), diag::libstdcxx_not_found, triple.str());
+  return clangDriverArgs;
+}
+
+static SmallVector<std::pair<std::string, std::string>, 2>
+getGlibcFileMapping(ASTContext &ctx) {
+  const llvm::Triple &triple = ctx.LangOpts.Target;
+  // We currently only need this when building for Linux.
+  if (!triple.isOSLinux())
+    return {};
+
+  // Extract the Glibc path from Clang driver.
+  auto clangDriver = createClangDriver(ctx);
+  auto clangDriverArgs = createClangArgs(ctx, clangDriver);
+
+  llvm::opt::ArgStringList includeArgStrings;
+  const auto &clangToolchain =
+      clangDriver.getToolChain(clangDriverArgs, triple);
+  clangToolchain.AddClangSystemIncludeArgs(clangDriverArgs, includeArgStrings);
+  auto parsedIncludeArgs = parseClangDriverArgs(clangDriver, includeArgStrings);
+
+  // Find the include path that contains Glibc headers. We use three arbitrarily
+  // chosen headers to determine if the include path actually contains Glibc.
+  // Ideally we would check that all of the headers referenced from the
+  // modulemap are present.
+  Path glibcDir;
+  if (auto dir = findFirstIncludeDir(parsedIncludeArgs,
+                                     {"inttypes.h", "unistd.h", "stdint.h"})) {
+    glibcDir = dir.getValue();
+  } else {
+    ctx.Diags.diagnose(SourceLoc(), diag::glibc_not_found, triple.str());
     return {};
   }
-  Path cxxStdlibDir(cxxStdlibDirs.front());
-  // VFS does not allow mapping paths that contain `../` or `./`.
-  llvm::sys::path::remove_dots(cxxStdlibDir, /*remove_dot_dot=*/true);
 
-  // Currently only a modulemap for libstdc++ is injected.
-  if (!ctx.LangOpts.EnableCXXInterop)
+  Path actualModuleMapPath;
+  if (auto path = getGlibcModuleMapPath(ctx.SearchPathOpts, triple))
+    actualModuleMapPath = path.getValue();
+  else
+    // FIXME: Emit a warning of some kind.
+    return {};
+
+  // Only inject the module map if it actually exists. It may not, for example
+  // if `swiftc -target x86_64-unknown-linux-gnu -emit-ir` is invoked using
+  // a Swift compiler not built for Linux targets.
+  if (!llvm::sys::fs::exists(actualModuleMapPath))
+    // FIXME: emit a warning of some kind.
+    return {};
+
+  // TODO: remove the SwiftGlibc.h header and reference all Glibc headers
+  // directly from the modulemap.
+  Path actualHeaderPath = actualModuleMapPath;
+  llvm::sys::path::remove_filename(actualHeaderPath);
+  llvm::sys::path::append(actualHeaderPath, "SwiftGlibc.h");
+
+  Path injectedModuleMapPath(glibcDir);
+  llvm::sys::path::append(injectedModuleMapPath, "module.modulemap");
+
+  Path injectedHeaderPath(glibcDir);
+  llvm::sys::path::append(injectedHeaderPath, "SwiftGlibc.h");
+
+  return {
+      {std::string(injectedModuleMapPath), std::string(actualModuleMapPath)},
+      {std::string(injectedHeaderPath), std::string(actualHeaderPath)},
+  };
+}
+
+static SmallVector<std::pair<std::string, std::string>, 2>
+getLibStdCxxFileMapping(ASTContext &ctx) {
+  assert(ctx.LangOpts.EnableCXXInterop &&
+         "libstdc++ is only injected if C++ interop is enabled");
+
+  const llvm::Triple &triple = ctx.LangOpts.Target;
+  // We currently only need this when building for Linux.
+  if (!triple.isOSLinux())
+    return {};
+  // Android uses libc++.
+  if (triple.isAndroid())
+    return {};
+
+  // Extract the libstdc++ installation path from Clang driver.
+  auto clangDriver = createClangDriver(ctx);
+  auto clangDriverArgs = createClangArgs(ctx, clangDriver);
+
+  llvm::opt::ArgStringList stdlibArgStrings;
+  const auto &clangToolchain =
+      clangDriver.getToolChain(clangDriverArgs, triple);
+  clangToolchain.AddClangCXXStdlibIncludeArgs(clangDriverArgs,
+                                              stdlibArgStrings);
+  auto parsedStdlibArgs = parseClangDriverArgs(clangDriver, stdlibArgStrings);
+
+  Path cxxStdlibDir;
+  if (auto dir = findFirstIncludeDir(parsedStdlibArgs,
+                                     {"cstdlib", "string", "vector"})) {
+    cxxStdlibDir = dir.getValue();
+  } else {
+    ctx.Diags.diagnose(SourceLoc(), diag::libstdcxx_not_found, triple.str());
     return {};
+  }
 
   Path actualModuleMapPath;
-  Path buffer;
-  if (auto path = getLibStdCxxModuleMapPath(ctx.SearchPathOpts, triple, buffer))
+  if (auto path = getLibStdCxxModuleMapPath(ctx.SearchPathOpts, triple))
     actualModuleMapPath = path.getValue();
   else
     return {};
@@ -140,14 +282,10 @@ swift::getClangInvocationFileMapping(ASTContext &ctx) {
   // Inject a modulemap into VFS for the libstdc++ directory.
   // Only inject the module map if the module does not already exist at
   // {sysroot}/usr/include/module.{map,modulemap}.
-  Path injectedModuleMapLegacyPath(cxxStdlibDir);
-  llvm::sys::path::append(injectedModuleMapLegacyPath, "module.map");
-  if (llvm::sys::fs::exists(injectedModuleMapLegacyPath))
-    return {};
-
-  Path injectedModuleMapPath(cxxStdlibDir);
-  llvm::sys::path::append(injectedModuleMapPath, "module.modulemap");
-  if (llvm::sys::fs::exists(injectedModuleMapPath))
+  Path injectedModuleMapPath;
+  if (auto path = getInjectedModuleMapPath(cxxStdlibDir))
+    injectedModuleMapPath = path.getValue();
+  else
     return {};
 
   Path injectedHeaderPath(cxxStdlibDir);
@@ -158,3 +296,15 @@ swift::getClangInvocationFileMapping(ASTContext &ctx) {
       {std::string(injectedHeaderPath), std::string(actualHeaderPath)},
   };
 }
+
+SmallVector<std::pair<std::string, std::string>, 2>
+swift::getClangInvocationFileMapping(ASTContext &ctx) {
+  SmallVector<std::pair<std::string, std::string>, 2> result;
+
+  result.append(getGlibcFileMapping(ctx));
+
+  if (ctx.LangOpts.EnableCXXInterop) {
+    result.append(getLibStdCxxFileMapping(ctx));
+  }
+  return result;
+}

lib/ClangImporter/ClangIncludePaths.h

@@ -14,23 +14,13 @@
 #define SWIFT_CLANG_INCLUDE_PATHS_H
 
 #include "swift/AST/ASTContext.h"
-#include "swift/AST/SearchPathOptions.h"
 
 namespace swift {
 
-/// Finds the glibc.modulemap file relative to the provided resource dir.
-///
-/// Note that the module map used for Glibc depends on the target we're
-/// compiling for, and is not included in the resource directory with the other
-/// implicit module maps. It's at {freebsd|linux}/{arch}/glibc.modulemap.
-Optional<StringRef> getGlibcModuleMapPath(SearchPathOptions &Opts,
-                                          llvm::Triple triple,
-                                          SmallVectorImpl<char> &buffer);
-
 /// On Linux, some platform libraries (glibc, libstdc++) are not modularized.
 /// We inject modulemaps for those libraries into their include directories
 /// to allow using them from Swift.
-SmallVector<std::pair<std::string, std::string>, 16>
+SmallVector<std::pair<std::string, std::string>, 2>
 getClangInvocationFileMapping(ASTContext &ctx);
 
 } // namespace swift