ClangIncludePaths.cpp

//===--- ClangIncludePaths.cpp --------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "ClangIncludePaths.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/DiagnosticEngine.h"
#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;

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()) {
    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(result))
      return result;
  }

  if (!Opts.RuntimeResourcePath.empty()) {
    result.clear();
    result.append(Opts.RuntimeResourcePath.begin(),
                  Opts.RuntimeResourcePath.end());
    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(result))
      return result;
  }

  return None;
}

/// 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;
}

/// 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);
}

static Optional<Path>
getLibStdCxxModuleMapPath(SearchPathOptions &opts, const llvm::Triple &triple) {
  return getActualModuleMapPath("libstdcxx.modulemap", opts, triple);
}

Optional<SmallString<128>>
swift::getCxxShimModuleMapPath(SearchPathOptions &opts,
                               const llvm::Triple &triple) {
  return getActualModuleMapPath("libcxxshim.modulemap", opts, triple);
}

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);
}

static clang::driver::Driver createClangDriver(const ASTContext &ctx) {
  auto clangDiags = clang::CompilerInstance::createDiagnostics(
      new clang::DiagnosticOptions());
  clang::driver::Driver clangDriver(ctx.ClangImporterOpts.clangPath,
                                    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.
  std::vector<const char *> clangArgs;
  for (const auto &each : ctx.ClangImporterOpts.ExtraArgs) {
    clangArgs.push_back(each.c_str());
  }
  llvm::opt::InputArgList clangDriverArgs =
      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();
  if (!sdkPath.empty())
    clangDriver.SysRoot = sdkPath.str();
  return clangDriverArgs;
}

static bool shouldInjectGlibcModulemap(const llvm::Triple &triple) {
  return triple.isOSGlibc() || triple.isOSOpenBSD() || triple.isOSFreeBSD() ||
         triple.isAndroid();
}

static SmallVector<std::pair<std::string, std::string>, 2>
getGlibcFileMapping(ASTContext &ctx) {
  const llvm::Triple &triple = ctx.LangOpts.Target;
  if (!shouldInjectGlibcModulemap(triple))
    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.value();
  } else {
    ctx.Diags.diagnose(SourceLoc(), diag::glibc_not_found, triple.str());
    return {};
  }

  Path actualModuleMapPath;
  if (auto path = getGlibcModuleMapPath(ctx.SearchPathOpts, triple))
    actualModuleMapPath = path.value();
  else
    // 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.value();
  } else {
    ctx.Diags.diagnose(SourceLoc(), diag::libstdcxx_not_found, triple.str());
    return {};
  }

  Path actualModuleMapPath;
  if (auto path = getLibStdCxxModuleMapPath(ctx.SearchPathOpts, triple))
    actualModuleMapPath = path.value();
  else
    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 libstdcxx.h header and reference all libstdc++ headers
  // directly from the modulemap.
  Path actualHeaderPath = actualModuleMapPath;
  llvm::sys::path::remove_filename(actualHeaderPath);
  llvm::sys::path::append(actualHeaderPath, "libstdcxx.h");

  // 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 injectedModuleMapPath;
  if (auto path = getInjectedModuleMapPath(cxxStdlibDir))
    injectedModuleMapPath = path.value();
  else
    return {};

  Path injectedHeaderPath(cxxStdlibDir);
  llvm::sys::path::append(injectedHeaderPath, "libstdcxx.h");

  return {
      {std::string(injectedModuleMapPath), std::string(actualModuleMapPath)},
      {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;
}