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/lib/Driver/Distro.cpp b/lib/Driver/Distro.cpp
index ee4fe841..f0313bbe 100644
--- a/lib/Driver/Distro.cpp
+++ b/lib/Driver/Distro.cpp
@@ -93,6 +93,10 @@ 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/lib/Driver/ToolChains/Cuda.cpp b/lib/Driver/ToolChains/Cuda.cpp
index d14776c5..88bc3ccd 100644
--- a/lib/Driver/ToolChains/Cuda.cpp
+++ b/lib/Driver/ToolChains/Cuda.cpp
@@ -119,6 +119,9 @@ 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/lib/Driver/ToolChains/Linux.cpp b/lib/Driver/ToolChains/Linux.cpp
index 9663a739..107f96d6 100644
--- a/lib/Driver/ToolChains/Linux.cpp
+++ b/lib/Driver/ToolChains/Linux.cpp
@@ -223,6 +223,9 @@ 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()) {
@@ -288,6 +291,7 @@ 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.
@@ -301,6 +305,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   Generic_GCC::AddMultilibPaths(D, SysRoot, OSLibDir, MultiarchTriple, Paths);
 
+#if 0
   // Similar to the logic for GCC above, if we currently running Clang inside
   // of the requested system root, add its parent library paths to
   // those searched.
@@ -352,9 +357,14 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   // directory ('Dir' below) or the ResourceDir.
   if (StringRef(D.Dir).startswith(SysRoot))
     addPathIfExists(D, D.Dir + "/../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);
 
-  addPathIfExists(D, SysRoot + "/lib", Paths);
-  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
+  // Add GCC's lib/ directory so libstdc++.so can be found.
+  addPathIfExists(D, GCCInstallation.getParentLibPath(), Paths);
 }
 
 ToolChain::CXXStdlibType Linux::GetDefaultCXXStdlibType() const {
 deprecated "-s" option.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/networking.scm (openntpd-configuration): Remove
"allow-large-adjustment?" field.
(openntpd-shepherd-service): Remove use of "allow-large-adjustment?"
configuration field and "-s" daemon option.
* tests/networking.scm (%openntpd-conf-sample): Remove
"allow-large-adjustment?" field.
* doc/guix.texi (Networking Services)[openntpd-service-type]: Remove
"allow-large-adjustment?" field from sample configuration.
[openntpd-configuration]: Remove description of "allow-large-adjustment?"
field.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Simon South</td></tr>