Commit 88bccded authored by Sam McCall's avatar Sam McCall
Browse files

[clangd] Try harder to find a plausible `clang` as argv0, particularly on Mac. 

Summary:
Fixes https://github.com/clangd/clangd/issues/211
Fixes https://github.com/clangd/clangd/issues/178

No tests - this is hard to test, and basically impossible to verify what we want
(this produces compile commands that work on a real mac with recent toolchain)

(Need someone on mac to verify it actually fixes these!)

Reviewers: kbobyrev, ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70863
parent 3540b80f

clang-tools-extra/clangd/GlobalCompilationDatabase.cpp

+137 −13
Original line number Diff line number Diff line
@@ -18,7 +18,9 @@ 
#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/SmallString.h"

#include "llvm/Support/FileSystem.h"

#include "llvm/Support/FileUtilities.h"

#include "llvm/Support/Path.h"

#include "llvm/Support/Program.h"

#include <string>

#include <tuple>

#include <vector>
@@ -27,6 +29,113 @@ namespace clang { 
namespace clangd {

namespace {



// Query apple's `xcrun` launcher, which is the source of truth for "how should"

// clang be invoked on this system.

llvm::Optional<std::string> queryXcrun(llvm::ArrayRef<llvm::StringRef> Argv) {

  auto Xcrun = llvm::sys::findProgramByName("xcrun");

  if (!Xcrun) {

    log("Couldn't find xcrun. Hopefully you have a non-apple toolchain...");

    return llvm::None;

  }

  llvm::SmallString<64> OutFile;

  llvm::sys::fs::createTemporaryFile("clangd-xcrun", "", OutFile);

  llvm::FileRemover OutRemover(OutFile);

  llvm::Optional<llvm::StringRef> Redirects[3] = {

      /*stdin=*/{""}, /*stdout=*/{OutFile}, /*stderr=*/{""}};

  vlog("Invoking {0} to find clang installation", *Xcrun);

  int Ret = llvm::sys::ExecuteAndWait(*Xcrun, Argv,

                                      /*Env=*/llvm::None, Redirects,

                                      /*SecondsToWait=*/10);

  if (Ret != 0) {

    log("xcrun exists but failed with code {0}. "

        "If you have a non-apple toolchain, this is OK. "

        "Otherwise, try xcode-select --install.",

        Ret);

    return llvm::None;

  }



  auto Buf = llvm::MemoryBuffer::getFile(OutFile);

  if (!Buf) {

    log("Can't read xcrun output: {0}", Buf.getError().message());

    return llvm::None;

  }

  StringRef Path = Buf->get()->getBuffer().trim();

  if (Path.empty()) {

    log("xcrun produced no output");

    return llvm::None;

  }

  return Path.str();

}



// On Mac, `which clang` is /usr/bin/clang. It runs `xcrun clang`, which knows

// where the real clang is kept. We need to do the same thing,

// because cc1 (not the driver!) will find libc++ relative to argv[0].

llvm::Optional<std::string> queryMacClangPath() {

#ifndef __APPLE__

  return llvm::None;

#endif



  return queryXcrun({"xcrun", "--find", "clang"});

}



// Resolve symlinks if possible.

std::string resolve(std::string Path) {

  llvm::SmallString<128> Resolved;

  if (llvm::sys::fs::real_path(Path, Resolved))

    return Path; // On error;

  return Resolved.str();

}



// Get a plausible full `clang` path.

// This is used in the fallback compile command, or when the CDB returns a

// generic driver with no path.

llvm::StringRef getFallbackClangPath() {

  static const std::string &MemoizedFallbackPath = [&]() -> std::string {

    // The driver and/or cc1 sometimes depend on the binary name to compute

    // useful things like the standard library location.

    // We need to emulate what clang on this system is likely to see.

    // cc1 in particular looks at the "real path" of the running process, and

    // so if /usr/bin/clang is a symlink, it sees the resolved path.

    // clangd doesn't have that luxury, so we resolve symlinks ourselves.



    // /usr/bin/clang on a mac is a program that redirects to the right clang.

    // We resolve it as if it were a symlink.

    if (auto MacClang = queryMacClangPath())

      return resolve(std::move(*MacClang));

    // On other platforms, just look for compilers on the PATH.

    for (const char* Name : {"clang", "gcc", "cc"})

      if (auto PathCC = llvm::sys::findProgramByName(Name))

        return resolve(std::move(*PathCC));

    // Fallback: a nonexistent 'clang' binary next to clangd.

    static int Dummy;

    std::string ClangdExecutable =

        llvm::sys::fs::getMainExecutable("clangd", (void *)&Dummy);

    SmallString<128> ClangPath;

    ClangPath = llvm::sys::path::parent_path(ClangdExecutable);

    llvm::sys::path::append(ClangPath, "clang");

    return ClangPath.str();

  }();

  return MemoizedFallbackPath;

}



// On mac, /usr/bin/clang sets SDKROOT and then invokes the real clang.

// The effect of this is to set -isysroot correctly. We do the same.

const std::string *getMacSysroot() {

#ifndef __APPLE__

  return nullptr;

#endif



  // SDKROOT overridden in environment, respect it. Driver will set isysroot.

  if (::getenv("SDKROOT"))

    return nullptr;

  static const llvm::Optional<std::string> &Sysroot =

      queryXcrun({"xcrun", "--show-sdk-path"});

  return Sysroot ? Sysroot.getPointer() : nullptr;

}



// Transform a command into the form we want to send to the driver.

// The command was originally either from the CDB or is the fallback command,

// and may have been modified by OverlayCDB.

void adjustArguments(tooling::CompileCommand &Cmd,

                     llvm::StringRef ResourceDir) {

  tooling::ArgumentsAdjuster ArgsAdjuster = tooling::combineAdjusters(
@@ -40,10 +149,35 @@ void adjustArguments(tooling::CompileCommand &Cmd, 
                                tooling::getClangSyntaxOnlyAdjuster()));



  Cmd.CommandLine = ArgsAdjuster(Cmd.CommandLine, Cmd.Filename);

  // Check whether the flag exists, either as -flag or -flag=*

  auto Has = [&](llvm::StringRef Flag) {

    for (llvm::StringRef Arg : Cmd.CommandLine) {

      if (Arg.consume_front(Flag) && (Arg.empty() || Arg[0] == '='))

        return true;

    }

    return false;

  };

  // Inject the resource dir.

  // FIXME: Don't overwrite it if it's already there.

  if (!ResourceDir.empty())

  if (!ResourceDir.empty() && !Has("-resource-dir"))

    Cmd.CommandLine.push_back(("-resource-dir=" + ResourceDir).str());

  if (!Has("-isysroot"))

    if (const std::string *MacSysroot = getMacSysroot()) {

      Cmd.CommandLine.push_back("-isysroot");

      Cmd.CommandLine.push_back(*MacSysroot);

    }



  // If the driver is a generic name like "g++" with no path, add a clang path.

  // This makes it easier for us to find the standard libraries on mac.

  if (!Cmd.CommandLine.empty()) {

    std::string &Driver = Cmd.CommandLine.front();

    if (Driver == "clang" || Driver == "clang++" || Driver == "gcc" ||

        Driver == "g++" || Driver == "cc" || Driver == "c++") {

      llvm::SmallString<128> QualifiedDriver =

          llvm::sys::path::parent_path(getFallbackClangPath());

      llvm::sys::path::append(QualifiedDriver, Driver);

      Driver = QualifiedDriver.str();

    }

  }

}



std::string getStandardResourceDir() {
@@ -63,19 +197,9 @@ void actOnAllParentDirectories(PathRef FileName, 


} // namespace



static std::string getFallbackClangPath() {

  static int Dummy;

  std::string ClangdExecutable =

      llvm::sys::fs::getMainExecutable("clangd", (void *)&Dummy);

  SmallString<128> ClangPath;

  ClangPath = llvm::sys::path::parent_path(ClangdExecutable);

  llvm::sys::path::append(ClangPath, "clang");

  return ClangPath.str();

}



tooling::CompileCommand

GlobalCompilationDatabase::getFallbackCommand(PathRef File) const {

  std::vector<std::string> Argv = {getFallbackClangPath()};

  std::vector<std::string> Argv = {"clang"};

  // Clang treats .h files as C by default and files without extension as linker

  // input, resulting in unhelpful diagnostics.

  // Parsing as Objective C++ is friendly to more cases.

clang-tools-extra/clangd/unittests/BackgroundIndexTests.cpp

+2 −2
Original line number Diff line number Diff line
@@ -542,7 +542,7 @@ TEST_F(BackgroundIndexTest, CmdLineHash) { 
  FS.Files[testPath("A.h")] = "";

  Cmd.Filename = "../A.cc";

  Cmd.Directory = testPath("build");

  Cmd.CommandLine = {"clang++", "../A.cc", "-fsyntax-only"};

  Cmd.CommandLine = {"/bin/clang++", "../A.cc", "-fsyntax-only"};

  CDB.setCompileCommand(testPath("build/../A.cc"), Cmd);

  ASSERT_TRUE(Idx.blockUntilIdleForTest());
@@ -558,7 +558,7 @@ TEST_F(BackgroundIndexTest, CmdLineHash) { 


  // FIXME: Changing compile commands should be enough to invalidate the cache.

  FS.Files[testPath("A.cc")] = " ";

  Cmd.CommandLine = {"clang++", "../A.cc", "-Dfoo", "-fsyntax-only"};

  Cmd.CommandLine = {"/bin/clang++", "../A.cc", "-Dfoo", "-fsyntax-only"};

  CDB.setCompileCommand(testPath("build/../A.cc"), Cmd);

  ASSERT_TRUE(Idx.blockUntilIdleForTest());

clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp

+3 −2
Original line number Diff line number Diff line
@@ -105,8 +105,9 @@ TEST_F(OverlayCDBTest, GetCompileCommand) { 
TEST_F(OverlayCDBTest, GetFallbackCommand) {

  OverlayCDB CDB(Base.get(), {"-DA=4"});

  EXPECT_THAT(CDB.getFallbackCommand(testPath("bar.cc")).CommandLine,

              ElementsAre("clang", "-DA=2", testPath("bar.cc"), "-DA=4",

                          "-fsyntax-only", StartsWith("-resource-dir")));

              ElementsAre(EndsWith("clang"), "-DA=2", testPath("bar.cc"),

                          "-DA=4", "-fsyntax-only",

                          StartsWith("-resource-dir")));

}



TEST_F(OverlayCDBTest, NoBase) {