Update libc++ include path detection to use VFS on Linux

[juliehockett]

Summary

The DetectLibcxxIncludePath function had been using llvm::sys::fs::directory_iterator, and this updates it to use llvm::vfs::directory_iterator.

[phosek]

LGTM

clang/lib/Driver/ToolChains/Linux.cpp

868 ↗

(On Diff #208546)

Nit: can you make vfs the first argument?

cfe/trunk/lib/Driver/ToolChains/Linux.cpp

void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   // Add an include of '/include' directly. This isn't provided by default by
   // system GCCs, but is often used with cross-compiling GCCs, and harmless to
   // add even when Clang is acting as-if it were a system compiler.
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");
 
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
 }
 
-static std::string DetectLibcxxIncludePath(StringRef base) {
+static std::string DetectLibcxxIncludePath(llvm::vfs::FileSystem &vfs,
+                                           StringRef base) {
   std::error_code EC;
   int MaxVersion = 0;
   std::string MaxVersionString = "";
-  for (llvm::sys::fs::directory_iterator LI(base, EC), LE; !EC && LI != LE;
-       LI = LI.increment(EC)) {
+  for (llvm::vfs::directory_iterator LI = vfs.dir_begin(base, EC), LE;
+       !EC && LI != LE; LI = LI.increment(EC)) {
     StringRef VersionText = llvm::sys::path::filename(LI->path());
     int Version;
     if (VersionText[0] == 'v' &&
         !VersionText.slice(1, StringRef::npos).getAsInteger(10, Version)) {
       if (Version > MaxVersion) {
         MaxVersion = Version;
         MaxVersionString = VersionText;
       }
     }
   }
   return MaxVersion ? (base + "/" + MaxVersionString).str() : "";
 }
 
 void Linux::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                   llvm::opt::ArgStringList &CC1Args) const {
   const std::string& SysRoot = computeSysRoot();
   const std::string LibCXXIncludePathCandidates[] = {
-      DetectLibcxxIncludePath(getDriver().Dir + "/../include/c++"),
+      DetectLibcxxIncludePath(getVFS(), getDriver().Dir + "/../include/c++"),
       // If this is a development, non-installed, clang, libcxx will
       // not be found at ../include/c++ but it likely to be found at
       // one of the following two locations:
-      DetectLibcxxIncludePath(SysRoot + "/usr/local/include/c++"),
-      DetectLibcxxIncludePath(SysRoot + "/usr/include/c++") };
+      DetectLibcxxIncludePath(getVFS(), SysRoot + "/usr/local/include/c++"),
+      DetectLibcxxIncludePath(getVFS(), SysRoot + "/usr/include/c++") };
   for (const auto &IncludePath : LibCXXIncludePathCandidates) {
     if (IncludePath.empty() || !getVFS().exists(IncludePath))
       continue;
     // Use the first candidate that exists.
     addSystemInclude(DriverArgs, CC1Args, IncludePath);
     return;
   }
 }