On platforms where clang is the default compiler, don't build gcc or libstdc++.

To enable them, set WITH_GCC and WITH_GNUCXX in src.conf.
Make clang default to using libc++ on FreeBSD 10.
Bumped __FreeBSD_version for the change.

GCC is still enabled on PC98, because the PC98 bootloader requires GCC to build
(or, at least, hard-codes the use of gcc into its build).

Thanks to everyone who helped make the ports tree ready for this (and bapt
for coordinating them all).  Also to imp for reviewing this and working on the
forward-porting of the changes in our gcc so that we're getting to a much
better place with regard to external toolchains.

Sorry to all of the people who helped who I forgot to mention by name.

Reviewed by:	bapt, imp, dim, ...

contrib/llvm/tools/clang/lib/Driver/ToolChains.cpp

@@ -1851,6 +1851,38 @@ bool FreeBSD::UseSjLjExceptions() const {
   }
 }
 
+ToolChain::CXXStdlibType
+FreeBSD::GetCXXStdlibType(const ArgList &Args) const {
+  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
+    StringRef Value = A->getValue();
+    if (Value == "libc++")
+      return ToolChain::CST_Libcxx;
+    if (Value == "libstdc++")
+      return ToolChain::CST_Libstdcxx;
+    getDriver().Diag(diag::err_drv_invalid_stdlib_name)
+      << A->getAsString(Args);
+  }
+
+  return getTriple().getOSMajorVersion() >= 10 ? ToolChain::CST_Libcxx :
+         ToolChain::CST_Libstdcxx;
+}
+
+void FreeBSD::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
+                                          ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
+      DriverArgs.hasArg(options::OPT_nostdincxx))
+    return;
+
+  if (GetCXXStdlibType(DriverArgs) == ToolChain::CST_Libcxx)
+    addSystemInclude(DriverArgs, CC1Args,
+                     getDriver().SysRoot + "/usr/include/c++/v1");
+  else
+    addSystemInclude(DriverArgs, CC1Args,
+                     getDriver().SysRoot + "/usr/include/c++/4.2");
+  return;
+
+}
+
 /// NetBSD - NetBSD tool chain which can call as(1) and ld(1) directly.
 
 NetBSD::NetBSD(const Driver &D, const llvm::Triple& Triple, const ArgList &Args)

contrib/llvm/tools/clang/lib/Driver/ToolChains.h

@@ -458,9 +458,14 @@ class LLVM_LIBRARY_VISIBILITY FreeBSD : public Generic_ELF {
 public:
   FreeBSD(const Driver &D, const llvm::Triple& Triple, const ArgList &Args);
 
+  virtual CXXStdlibType GetCXXStdlibType(const ArgList &Args) const;
+
   virtual bool IsMathErrnoDefault() const { return false; }
   virtual bool IsObjCNonFragileABIDefault() const { return true; }
 
+  virtual void AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
+                                            ArgStringList &CC1Args) const;
+
   virtual bool UseSjLjExceptions() const;
 protected:
   virtual Tool *buildAssembler() const;

gnu/lib/Makefile

@@ -10,7 +10,7 @@ SUBDIR+= libssp
 
 # libsupc++ uses libstdc++ headers, although 'make includes' should
 # have taken care of that already.
-.if ${MK_CXX} != "no"
+.if ${MK_GNUCXX} != "no"
 SUBDIR+= libstdc++ libsupc++
 .endif
 

gnu/usr.bin/cc/Makefile

@@ -12,7 +12,12 @@ SUBDIR+= cpp
 .endif
 
 .if ${MK_CXX} != "no"
-SUBDIR+= cc1plus c++ c++filt
+.if ${MK_GNUCXX} != "no"
+SUBDIR+= cc1plus c++ 
+.endif
+# This should be moved into the above block once c++filt from elftoolchain or
+# similar is provided.
+SUBDIR+= c++filt
 .endif
 
 .if ${MK_GCOV} != "no"

share/mk/bsd.own.mk

@@ -284,7 +284,6 @@ __DEFAULT_YES_OPTIONS = \
     FP_LIBC \
     FREEBSD_UPDATE \
     GAMES \
-    GCC \
     GCOV \
     GDB \
     GNU \
@@ -400,6 +399,11 @@ __T=${TARGET_ARCH}
 .else
 __T=${MACHINE_ARCH}
 .endif
+.if defined(TARGET)
+__TT=${TARGET}
+.else
+__TT=${MACHINE_ARCH}
+.endif
 # Clang is only for x86, powerpc and little-endian arm right now, by default.
 .if ${__T} == "amd64" || ${__T} == "i386" || ${__T:Mpowerpc*}
 __DEFAULT_YES_OPTIONS+=CLANG CLANG_FULL
@@ -414,8 +418,30 @@ __DEFAULT_NO_OPTIONS+=CLANG CLANG_FULL
 .if ${__T} == "amd64" || ${__T} == "arm" || ${__T} == "armv6" || \
     ${__T} == "i386"
 __DEFAULT_YES_OPTIONS+=CLANG_IS_CC
+# The pc98 bootloader requires gcc to build and so we must leave gcc enabled
+# for pc98 for now.
+.if ${__TT} == "pc98"
+__DEFAULT_NO_OPTIONS+=GNUCXX
+__DEFAULT_YES_OPTIONS+=GCC
 .else
+__DEFAULT_NO_OPTIONS+=GCC GNUCXX
+.endif
+# The libc++ headers use c++11 extensions.  These are normally silenced because
+# they are treated as system headers, but we explicitly disable that warning
+# suppression when building the base system to catch bugs in our headers.
+# Eventually we'll want to start building the base system C++ code as C++11,
+# but not yet.
+CXXFLAGS+=	-Wno-c++11-extensions
+.else
+# If clang is not cc, then build gcc by default
 __DEFAULT_NO_OPTIONS+=CLANG_IS_CC
+__DEFAULT_YES_OPTIONS+=GCC
+# And if g++ is c++, build the rest of the GNU C++ stack
+.if defined(WITHOUT_CXX)
+__DEFAULT_NO_OPTIONS+=GNUCXX
+.else
+__DEFAULT_YES_OPTIONS+=GNUCXX
+.endif
 .endif
 # FDT is needed only for arm, mips and powerpc
 .if ${__T:Marm*} || ${__T:Mpowerpc*} || ${__T:Mmips*}

sys/sys/param.h

@@ -58,7 +58,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1000053	/* Master, propagated to newvers */
+#define __FreeBSD_version 1000054	/* Master, propagated to newvers */
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,

tools/build/options/WITHOUT_GNUCXX

@@ -0,0 +1,3 @@
+.\" $FreeBSD$
+Do not build the GNU C++ stack (g++, libstdc++).
+This is the default on platforms where clang is the system compiler.

tools/build/options/WITH_GNUCXX

@@ -0,0 +1,3 @@
+.\" $FreeBSD$
+Build the GNU C++ stack (g++, libstdc++).
+This is the default on platforms where gcc is the system compiler.