[Driver] Move detectLibcxxIncludePath to ToolChain

This helper method is useful even outside of Gnu toolchains, so move
it to ToolChain so it can be reused in other toolchains such as Fuchsia.

Differential Revision: https://reviews.llvm.org/D88452

Author: petrhosek

clang/include/clang/Driver/ToolChain.h

@@ -575,6 +575,9 @@ class ToolChain {
   // given compilation arguments.
   virtual UnwindLibType GetUnwindLibType(const llvm::opt::ArgList &Args) const;
 
+  // Detect the highest available version of libc++ in base path.
+  virtual std::string detectLibcxxIncludePath(StringRef Base) const;
+
   /// AddClangCXXStdlibIncludeArgs - Add the clang -cc1 level arguments to set
   /// the include paths to use for the given C++ standard library type.
   virtual void

clang/lib/Driver/ToolChain.cpp

@@ -924,6 +924,29 @@ void ToolChain::addExternCSystemIncludeIfExists(const ArgList &DriverArgs,
   }
 }
 
+std::string ToolChain::detectLibcxxIncludePath(StringRef Base) const {
+  std::error_code EC;
+  int MaxVersion = 0;
+  std::string MaxVersionString;
+  for (llvm::vfs::directory_iterator LI = getVFS().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 = std::string(VersionText);
+      }
+    }
+  }
+  if (!MaxVersion)
+    return "";
+  SmallString<128> P(Base);
+  llvm::sys::path::append(P, MaxVersionString);
+  return std::string(P.str());
+}
+
 void ToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                              ArgStringList &CC1Args) const {
   // Header search paths should be handled by each of the subclasses.

clang/lib/Driver/ToolChains/Fuchsia.cpp

@@ -319,8 +319,8 @@ void Fuchsia::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   switch (GetCXXStdlibType(DriverArgs)) {
   case ToolChain::CST_Libcxx: {
     SmallString<128> P(getDriver().Dir);
-    llvm::sys::path::append(P, "..", "include", "c++", "v1");
-    addSystemInclude(DriverArgs, CC1Args, P.str());
+    llvm::sys::path::append(P, "..", "include", "c++");
+    addSystemInclude(DriverArgs, CC1Args, detectLibcxxIncludePath(P.str()));
     break;
   }
 

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -2877,31 +2877,11 @@ void Generic_GCC::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   }
 }
 
-static std::string DetectLibcxxIncludePath(llvm::vfs::FileSystem &vfs,
-                                           StringRef base) {
-  std::error_code EC;
-  int MaxVersion = 0;
-  std::string MaxVersionString;
-  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 = std::string(VersionText);
-      }
-    }
-  }
-  return MaxVersion ? (base + "/" + MaxVersionString).str() : "";
-}
-
 void
 Generic_GCC::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args) const {
   auto AddIncludePath = [&](std::string Path) {
-    std::string IncludePath = DetectLibcxxIncludePath(getVFS(), Path);
+    std::string IncludePath = detectLibcxxIncludePath(Path);
     if (IncludePath.empty() || !getVFS().exists(IncludePath))
       return false;
     addSystemInclude(DriverArgs, CC1Args, IncludePath);