Clang attempts to guess file names based on the OS and distro (yes!),
but unfortunately, that doesn't work for us.

This patch makes it easy to insert libc's $libdir so that Clang passes the
correct absolute file name of crt1.o etc. to 'ld'.  It also disables all
the distro-specific stuff and removes the hard-coded FHS directory names
to make sure Clang also works on foreign distros.

diff --git a/clang/lib/Driver/Distro.cpp b/clang/libDriver/Distro.cpp
index 1898667..35de813 100644
--- a/clang/lib/Driver/Distro.cpp
+++ b/clang/libDriver/Distro.cpp
@@ -97,6 +97,10 @@ static Distro::DistroType DetectLsbRelease(llvm::vfs::FileSystem &VFS) {
 }
 
 static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
+  // The compiler should always behave the same, even when used via Guix on a
+  // foreign distro.
+  return Distro::UnknownDistro;
+
   Distro::DistroType Version = Distro::UnknownDistro;
 
   // Newer freedesktop.org's compilant systemd-based systems
diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/libDriver/ToolChains/Cuda.cpp
index 7ad990d..e4da4d4 100644
--- a/clang/lib/Driver/ToolChains/Cuda.cpp
+++ b/clang/libDriver/ToolChains/Cuda.cpp
@@ -117,6 +117,9 @@ CudaInstallationDetector::CudaInstallationDetector(
     const Driver &D, const llvm::Triple &HostTriple,
     const llvm::opt::ArgList &Args)
     : D(D) {
+  // Don't look for CUDA in /usr.
+  return;
+
   struct Candidate {
     std::string Path;
     bool StrictChecking;
diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/libDriver/ToolChains/Linux.cpp
index ceb1a98..9d7a14a 100644
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/libDriver/ToolChains/Linux.cpp
@@ -188,6 +188,10 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   Generic_GCC::PushPPaths(PPaths);
 
+  // Comment out the distro-specific tweaks so that they don't bite when
+  // using Guix on a foreign distro.
+#if 0
+
   Distro Distro(D.getVFS(), Triple);
 
   if (Distro.IsAlpineLinux() || Triple.isAndroid()) {
@@ -256,6 +260,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   if (IsAndroid || Distro.IsOpenSUSE())
     ExtraOpts.push_back("--enable-new-dtags");
+#endif
 
   // The selection of paths to try here is designed to match the patterns which
   // the GCC driver itself uses, as this is part of the GCC-compatible driver.
@@ -276,6 +281,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   }
   Generic_GCC::AddMultilibPaths(D, SysRoot, OSLibDir, MultiarchTriple, Paths);
 
+#if 0
   addPathIfExists(D, concat(SysRoot, "/lib", MultiarchTriple), Paths);
   addPathIfExists(D, concat(SysRoot, "/lib/..", OSLibDir), Paths);
 
@@ -304,9 +310,11 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     addPathIfExists(D, concat(SysRoot, "/", OSLibDir, ABIName), Paths);
     addPathIfExists(D, concat(SysRoot, "/usr", OSLibDir, ABIName), Paths);
   }
+#endif
 
   Generic_GCC::AddMultiarchPaths(D, SysRoot, OSLibDir, Paths);
 
+#if 0
   // The deprecated -DLLVM_ENABLE_PROJECTS=libcxx configuration installs
   // libc++.so in D.Dir+"/../lib/". Detect this path.
   // TODO Remove once LLVM_ENABLE_PROJECTS=libcxx is unsupported.
@@ -316,6 +324,14 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   addPathIfExists(D, concat(SysRoot, "/lib"), Paths);
   addPathIfExists(D, concat(SysRoot, "/usr/lib"), Paths);
+#endif
+
+  // Add libc's lib/ directory to the search path, so that crt1.o, crti.o,
+  // and friends can be found.
+  addPathIfExists(D, "@GLIBC_LIBDIR@", Paths);
+
+  // Add GCC's lib/ directory so libstdc++.so can be found.
+  addPathIfExists(D, GCCInstallation.getParentLibPath(), Paths);
 }
 
 ToolChain::RuntimeLibType Linux::GetDefaultRuntimeLibType() const {
kell-crypto.scm, gnu/packages/haskell-xyz.scm,
gnu/packages/haskell.scm, gnu/packages/image-viewers.scm,
gnu/packages/image.scm, gnu/packages/irc.scm, gnu/packages/language.scm,
gnu/packages/libcanberra.scm, gnu/packages/linux.scm,
gnu/packages/lisp-xyz.scm, gnu/packages/lisp.scm, gnu/packages/lolcode.scm,
gnu/packages/lxde.scm, gnu/packages/lxqt.scm, gnu/packages/mail.scm,
gnu/packages/markup.scm, gnu/packages/mate.scm, gnu/packages/maths.scm,
gnu/packages/mc.scm, gnu/packages/messaging.scm, gnu/packages/music.scm,
gnu/packages/ncurses.scm, gnu/packages/networking.scm,
gnu/packages/nickle.scm, gnu/packages/openbox.scm, gnu/packages/pdf.scm,
gnu/packages/perl-check.scm, gnu/packages/perl.scm,
gnu/packages/python-compression.scm, gnu/packages/python-crypto.scm,
gnu/packages/python-web.scm, gnu/packages/python-xyz.scm,
gnu/packages/python.scm, gnu/packages/qt.scm, gnu/packages/ruby.scm,
gnu/packages/rust.scm, gnu/packages/scheme.scm,
gnu/packages/serialization.scm, gnu/packages/shells.scm,
gnu/packages/ssh.scm, gnu/packages/suckless.scm, gnu/packages/tbb.scm,
gnu/packages/telephony.scm, gnu/packages/text-editors.scm,
gnu/packages/textutils.scm, gnu/packages/time.scm, gnu/packages/tls.scm,
gnu/packages/tor.scm, gnu/packages/version-control.scm,
gnu/packages/video.scm, gnu/packages/vim.scm, gnu/packages/web.scm,
gnu/packages/wm.scm, gnu/packages/xdisorg.scm, gnu/packages/xfce.scm,
gnu/packages/xml.scm, gnu/packages/xorg.scm, gnu/services/certbot.scm,
gnu/services/desktop.scm, gnu/services/version-control.scm,
gnu/services/web.scm, guix/import/hackage.scm, guix/licenses.scm: Likewise.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>
</span></span></td><td>nikita</td></tr>