Extend linux header search to find libc++ headers in c++/vN for any N.

[eugenis]

Summary

This goes with the ABI versioning support in libc++ in http://reviews.llvm.org/D11740

[jroelofs]

lib/Driver/ToolChains.cpp

3535

StringRef instead?

3563–3564

Kill the FIXME while you're here fixing what the FIXME complains about.

[eugenis]

ping
We will need this when libc++ is bumped to v2. There are no plans to do this AFAIK but the ABI version macros are in so it is possible and clang should be ready.

[jroelofs]

LGTM

lib/Driver/ToolChains.cpp

3545

Since you've got logic here to pick the newest headers, you should also have a tree that has both usr/include/c++/v1 and usr/include/c++/v2 to test that part of this change.

It's probably also a good idea to have a tree laid out as if libstdc++ and libc++ were both installed, i.e. both usr/include/c++/v1 and usr/include/c++/5.0 in it.

[eugenis]

r252514

lib/Driver/ToolChains.cpp

if ((GCCMultiarchTriple.empty() && TargetMultiarchTriple.empty()) ||
     addSystemInclude(DriverArgs, CC1Args,
                      Base + "/" + TargetMultiarchTriple + Suffix);
   }
 
   addSystemInclude(DriverArgs, CC1Args, Base + Suffix + "/backward");
   return true;
 }
 
+static std::string DetectLibcxxIncludePath(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)) {
+    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::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
       DriverArgs.hasArg(options::OPT_nostdincxx))
     return;
 
   // Check if libc++ has been enabled and provide its include paths if so.
   if (GetCXXStdlibType(DriverArgs) == ToolChain::CST_Libcxx) {
     const std::string LibCXXIncludePathCandidates[] = {
         // The primary location is within the Clang installation.
-        // FIXME: We shouldn't hard code 'v1' here to make Clang future proof to
-        // newer ABI versions.
-        getDriver().Dir + "/../include/c++/v1",
+        DetectLibcxxIncludePath(getDriver().Dir + "/../include/c++"),
 
         // We also check the system as for a long time this is the only place
         // Clang looked.
         // FIXME: We should really remove this. It doesn't make any sense.
-        getDriver().SysRoot + "/usr/include/c++/v1"};
+        DetectLibcxxIncludePath(getDriver().SysRoot + "/usr/include/c++")};
     for (const auto &IncludePath : LibCXXIncludePathCandidates) {
-      if (!llvm::sys::fs::exists(IncludePath))
+      if (IncludePath.empty() || !llvm::sys::fs::exists(IncludePath))
         continue;
       // Add the first candidate that exists.
       addSystemInclude(DriverArgs, CC1Args, IncludePath);
       break;
     }
     return;
   }
 

test/Driver/linux-header-search.cpp

 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-INSTALL %s
 // CHECK-BASIC-LIBCXX-INSTALL: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
 // CHECK-BASIC-LIBCXX-INSTALL: "-isysroot" "[[SYSROOT:[^"]+]]"
 // CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v1"
 // CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 //
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
+// RUN:     -target x86_64-unknown-linux-gnu \
+// RUN:     -stdlib=libc++ \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxxv2_tree \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXXV2-SYSROOT %s
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v2"
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
+// RUN:     -target x86_64-unknown-linux-gnu \
+// RUN:     -stdlib=libc++ \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxxv2_tree/usr/bin \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxxv2_tree \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXXV2-INSTALL %s
+// CHECK-BASIC-LIBCXXV2-INSTALL: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
+// CHECK-BASIC-LIBCXXV2-INSTALL: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v2"
+// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+//
 // Test a very broken version of multiarch that shipped in Ubuntu 11.04.
 // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
 // RUN:     -target i386-unknown-linux \
 // RUN:     --sysroot=%S/Inputs/ubuntu_11.04_multiarch_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-UBUNTU-11-04 %s
 // CHECK-UBUNTU-11-04: "{{.*}}clang{{.*}}" "-cc1"
 // CHECK-UBUNTU-11-04: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"