[Darwin] Add a warning for missing include path for libstdc++

[arphaman]

Summary

Xcode 10 removes support for libstdc++, but the users just get a confusing include not file warning when including an STL header (when building for iOS6 which uses libstdc++ by default for example).
This patch adds a new warning that lets the user know that the libstdc++ include path was not found to ensure that the user is more aware of why the error occurs.

rdar://40830462

[bruno]

lib/Frontend/InitHeaderSearch.cpp

491 ↗

(On Diff #151786)

If we happen to suggest libc++, but it's also not there, do we still want the warning? Should we check it exists first?

[arphaman]

lib/Frontend/InitHeaderSearch.cpp

491 ↗

(On Diff #151786)

I don't think such a check is that valuable on Darwin, which is where this warning fires, since libc++ is the default standard library on Darwin.

[vsapsai]

lib/Frontend/InitHeaderSearch.cpp

374–377 ↗

(On Diff #151786)

Why are you using &= here instead of |=? I haven't tested but I expect that either 4.2.1 will work or 4.0.0, you don't need both of them.

404 ↗

(On Diff #151786)

What is so special about CUDA? Is it OK to emit the warning for OpenCL, for instance?

test/Frontend/warning-stdlibcxx-darwin.cpp

1–2 ↗

(On Diff #151786)

Do you think there is a value in adding a test that does exactly what the warning suggests and verifies there are no warnings?

[arphaman]

lib/Frontend/InitHeaderSearch.cpp

374–377 ↗

(On Diff #151786)

Good catch, fixed.

404 ↗

(On Diff #151786)

We're looking to warn for pure C++/ObjC++, so I will disable it for other language dialects.

test/Frontend/warning-stdlibcxx-darwin.cpp

1–2 ↗

(On Diff #151786)

Good call.

[arphaman]

Addressed review comments

[bruno]

LGTM

cfe/trunk/include/clang/Basic/DiagnosticFrontendKinds.td

 
 def err_missing_vfs_overlay_file : Error<
   "virtual filesystem overlay file '%0' not found">, DefaultFatal;
 def err_invalid_vfs_overlay : Error<
   "invalid virtual filesystem overlay file '%0'">, DefaultFatal;
 
 def warn_option_invalid_ocl_version : Warning<
   "OpenCL version %0 does not support the option '%1'">, InGroup<Deprecated>;
+
+def warn_stdlibcxx_not_found : Warning<
+  "include path for stdlibc++ headers not found; pass '-std=libc++' on the "
+  "command line to use the libc++ standard library instead">,
+  InGroup<DiagGroup<"stdlibcxx-not-found">>;
 }

cfe/trunk/include/clang/Lex/HeaderSearch.h

public:
   ~HeaderSearch();
 
   /// Retrieve the header-search options with which this header search
   /// was initialized.
   HeaderSearchOptions &getHeaderSearchOpts() const { return *HSOpts; }
   
   FileManager &getFileMgr() const { return FileMgr; }
 
+  DiagnosticsEngine &getDiags() const { return Diags; }
+
   /// Interface for setting the file search paths.
   void SetSearchPaths(const std::vector<DirectoryLookup> &dirs,
                       unsigned angledDirIdx, unsigned systemDirIdx,
                       bool noCurDirSearch) {
     assert(angledDirIdx <= systemDirIdx && systemDirIdx <= dirs.size() &&
         "Directory indices are unordered");
     SearchDirs = dirs;
     AngledDirIdx = angledDirIdx;

cfe/trunk/lib/Frontend/InitHeaderSearch.cpp

 //===--- InitHeaderSearch.cpp - Initialize header search paths ------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the InitHeaderSearch class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Config/config.h" // C_INCLUDE_DIRS
+#include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/Utils.h"
 #include "clang/Lex/HeaderMap.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/HeaderSearchOptions.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
public:
 
   InitHeaderSearch(HeaderSearch &HS, bool verbose, StringRef sysroot)
     : Headers(HS), Verbose(verbose), IncludeSysroot(sysroot),
       HasSysroot(!(sysroot.empty() || sysroot == "/")) {
   }
 
   /// AddPath - Add the specified path to the specified group list, prefixing
   /// the sysroot if used.
-  void AddPath(const Twine &Path, IncludeDirGroup Group, bool isFramework);
+  /// Returns true if the path exists, false if it was ignored.
+  bool AddPath(const Twine &Path, IncludeDirGroup Group, bool isFramework);
 
   /// AddUnmappedPath - Add the specified path to the specified group list,
   /// without performing any sysroot remapping.
-  void AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
+  /// Returns true if the path exists, false if it was ignored.
+  bool AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
                        bool isFramework);
 
   /// AddSystemHeaderPrefix - Add the specified prefix to the system header
   /// prefix list.
   void AddSystemHeaderPrefix(StringRef Prefix, bool IsSystemHeader) {
     SystemHeaderPrefixes.emplace_back(Prefix, IsSystemHeader);
   }
 
   /// AddGnuCPlusPlusIncludePaths - Add the necessary paths to support a gnu
   ///  libstdc++.
-  void AddGnuCPlusPlusIncludePaths(StringRef Base,
-                                   StringRef ArchDir,
-                                   StringRef Dir32,
-                                   StringRef Dir64,
+  /// Returns true if the \p Base path was found, false if it does not exist.
+  bool AddGnuCPlusPlusIncludePaths(StringRef Base, StringRef ArchDir,
+                                   StringRef Dir32, StringRef Dir64,
                                    const llvm::Triple &triple);
 
   /// AddMinGWCPlusPlusIncludePaths - Add the necessary paths to support a MinGW
   ///  libstdc++.
   void AddMinGWCPlusPlusIncludePaths(StringRef Base,
                                      StringRef Arch,
                                      StringRef Version);
 
   // AddDefaultCIncludePaths - Add paths that should always be searched.
   void AddDefaultCIncludePaths(const llvm::Triple &triple,
                                const HeaderSearchOptions &HSOpts);
 
   // AddDefaultCPlusPlusIncludePaths -  Add paths that should be searched when
   //  compiling c++.
-  void AddDefaultCPlusPlusIncludePaths(const llvm::Triple &triple,
+  void AddDefaultCPlusPlusIncludePaths(const LangOptions &LangOpts,
+                                       const llvm::Triple &triple,
                                        const HeaderSearchOptions &HSOpts);
 
   /// AddDefaultSystemIncludePaths - Adds the default system include paths so
   ///  that e.g. stdio.h is found.
   void AddDefaultIncludePaths(const LangOptions &Lang,
                               const llvm::Triple &triple,
                               const HeaderSearchOptions &HSOpts);
 
   /// Realize - Merges all search path lists into one list and send it to
   /// HeaderSearch.
   void Realize(const LangOptions &Lang);
 };
 
 }  // end anonymous namespace.
 
 static bool CanPrefixSysroot(StringRef Path) {
 #if defined(_WIN32)
   return !Path.empty() && llvm::sys::path::is_separator(Path[0]);
 #else
   return llvm::sys::path::is_absolute(Path);
 #endif
 }
 
-void InitHeaderSearch::AddPath(const Twine &Path, IncludeDirGroup Group,
+bool InitHeaderSearch::AddPath(const Twine &Path, IncludeDirGroup Group,
                                bool isFramework) {
   // Add the path with sysroot prepended, if desired and this is a system header
   // group.
   if (HasSysroot) {
     SmallString<256> MappedPathStorage;
     StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
     if (CanPrefixSysroot(MappedPathStr)) {
-      AddUnmappedPath(IncludeSysroot + Path, Group, isFramework);
-      return;
+      return AddUnmappedPath(IncludeSysroot + Path, Group, isFramework);
     }
   }
 
-  AddUnmappedPath(Path, Group, isFramework);
+  return AddUnmappedPath(Path, Group, isFramework);
 }
 
-void InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
+bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
                                        bool isFramework) {
   assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
 
   FileManager &FM = Headers.getFileMgr();
   SmallString<256> MappedPathStorage;
   StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
 
   // Compute the DirectoryLookup type.
   SrcMgr::CharacteristicKind Type;
   if (Group == Quoted || Group == Angled || Group == IndexHeaderMap) {
     Type = SrcMgr::C_User;
   } else if (Group == ExternCSystem) {
     Type = SrcMgr::C_ExternCSystem;
   } else {
     Type = SrcMgr::C_System;
   }
 
   // If the directory exists, add it.
   if (const DirectoryEntry *DE = FM.getDirectory(MappedPathStr)) {
     IncludePath.push_back(
       std::make_pair(Group, DirectoryLookup(DE, Type, isFramework)));
-    return;
+    return true;
   }
 
   // Check to see if this is an apple-style headermap (which are not allowed to
   // be frameworks).
   if (!isFramework) {
     if (const FileEntry *FE = FM.getFile(MappedPathStr)) {
       if (const HeaderMap *HM = Headers.CreateHeaderMap(FE)) {
         // It is a headermap, add it to the search path.
         IncludePath.push_back(
           std::make_pair(Group,
                          DirectoryLookup(HM, Type, Group == IndexHeaderMap)));
-        return;
+        return true;
       }
     }
   }
 
   if (Verbose)
     llvm::errs() << "ignoring nonexistent directory \""
                  << MappedPathStr << "\"\n";
+  return false;
 }
 
-void InitHeaderSearch::AddGnuCPlusPlusIncludePaths(StringRef Base,
+bool InitHeaderSearch::AddGnuCPlusPlusIncludePaths(StringRef Base,
                                                    StringRef ArchDir,
                                                    StringRef Dir32,
                                                    StringRef Dir64,
                                                    const llvm::Triple &triple) {
   // Add the base dir
-  AddPath(Base, CXXSystem, false);
+  bool IsBaseFound = AddPath(Base, CXXSystem, false);
 
   // Add the multilib dirs
   llvm::Triple::ArchType arch = triple.getArch();
   bool is64bit = arch == llvm::Triple::ppc64 || arch == llvm::Triple::x86_64;
   if (is64bit)
     AddPath(Base + "/" + ArchDir + "/" + Dir64, CXXSystem, false);
   else
     AddPath(Base + "/" + ArchDir + "/" + Dir32, CXXSystem, false);
 
   // Add the backward dir
   AddPath(Base + "/backward", CXXSystem, false);
+  return IsBaseFound;
 }
 
 void InitHeaderSearch::AddMinGWCPlusPlusIncludePaths(StringRef Base,
                                                      StringRef Arch,
                                                      StringRef Version) {
   AddPath(Base + "/" + Arch + "/" + Version + "/include/c++",
           CXXSystem, false);
   AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/" + Arch,
case llvm::Triple::PS4: {
     LLVM_FALLTHROUGH;
   }
   default:
     AddPath("/usr/include", ExternCSystem, false);
     break;
   }
 }
 
-void InitHeaderSearch::
-AddDefaultCPlusPlusIncludePaths(const llvm::Triple &triple, const HeaderSearchOptions &HSOpts) {
+void InitHeaderSearch::AddDefaultCPlusPlusIncludePaths(
+    const LangOptions &LangOpts, const llvm::Triple &triple,
+    const HeaderSearchOptions &HSOpts) {
   llvm::Triple::OSType os = triple.getOS();
   // FIXME: temporary hack: hard-coded paths.
 
   if (triple.isOSDarwin()) {
+    bool IsBaseFound = true;
     switch (triple.getArch()) {
     default: break;
 
     case llvm::Triple::ppc:
     case llvm::Triple::ppc64:
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
-                                  "powerpc-apple-darwin10", "", "ppc64",
-                                  triple);
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.0.0",
-                                  "powerpc-apple-darwin10", "", "ppc64",
-                                  triple);
+      IsBaseFound = AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
+                                                "powerpc-apple-darwin10", "",
+                                                "ppc64", triple);
+      IsBaseFound |= AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.0.0",
+                                                 "powerpc-apple-darwin10", "",
+                                                 "ppc64", triple);
       break;
 
     case llvm::Triple::x86:
     case llvm::Triple::x86_64:
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
-                                  "i686-apple-darwin10", "", "x86_64", triple);
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.0.0",
-                                  "i686-apple-darwin8", "", "", triple);
+      IsBaseFound = AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
+                                                "i686-apple-darwin10", "",
+                                                "x86_64", triple);
+      IsBaseFound |= AddGnuCPlusPlusIncludePaths(
+          "/usr/include/c++/4.0.0", "i686-apple-darwin8", "", "", triple);
       break;
 
     case llvm::Triple::arm:
     case llvm::Triple::thumb:
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
-                                  "arm-apple-darwin10", "v7", "", triple);
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
-                                  "arm-apple-darwin10", "v6", "", triple);
+      IsBaseFound = AddGnuCPlusPlusIncludePaths(
+          "/usr/include/c++/4.2.1", "arm-apple-darwin10", "v7", "", triple);
+      IsBaseFound |= AddGnuCPlusPlusIncludePaths(
+          "/usr/include/c++/4.2.1", "arm-apple-darwin10", "v6", "", triple);
       break;
 
     case llvm::Triple::aarch64:
-      AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
-                                  "arm64-apple-darwin10", "", "", triple);
+      IsBaseFound = AddGnuCPlusPlusIncludePaths(
+          "/usr/include/c++/4.2.1", "arm64-apple-darwin10", "", "", triple);
       break;
     }
+    // Warn when compiling pure C++ / Objective-C++ only.
+    if (!IsBaseFound &&
+        !(LangOpts.CUDA || LangOpts.OpenCL || LangOpts.RenderScript)) {
+      Headers.getDiags().Report(SourceLocation(),
+                                diag::warn_stdlibcxx_not_found);
+    }
     return;
   }
 
   switch (os) {
   case llvm::Triple::Linux:
   case llvm::Triple::Solaris:
     llvm_unreachable("Include management is handled in the driver.");
     break;
if (HSOpts.UseLibcxx) {
 
           // Get foo/include/c++/v1
           llvm::sys::path::append(P, "include", "c++", "v1");
           AddUnmappedPath(P, CXXSystem, false);
         }
       }
       AddPath("/usr/include/c++/v1", CXXSystem, false);
     } else {
-      AddDefaultCPlusPlusIncludePaths(triple, HSOpts);
+      AddDefaultCPlusPlusIncludePaths(Lang, triple, HSOpts);
     }
   }
 
   AddDefaultCIncludePaths(triple, HSOpts);
 
   // Add the default framework include paths on Darwin.
   if (HSOpts.UseStandardSystemIncludes) {
     if (triple.isOSDarwin()) {

cfe/trunk/test/Frontend/warning-stdlibcxx-darwin.cpp

+// RUN: %clang -cc1 -triple arm64-apple-ios6.0.0 -isysroot %S/doesnotexist %s 2>&1 | FileCheck %s
+// RUN: %clang -cc1 -triple arm64-apple-ios6.0.0 -isysroot %S/doesnotexist -stdlib=libc++ %s -verify
+// CHECK: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead
+
+// expected-no-diagnostics