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 non-Guix systems.

diff --git a/lib/Driver/ToolChains/Linux.cpp b/lib/Driver/ToolChains/Linux.cpp
index bff1ab10..79e1477e 100644
--- a/lib/Driver/ToolChains/Linux.cpp
+++ b/lib/Driver/ToolChains/Linux.cpp
@@ -240,6 +240,9 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
                          .str());
   }
 
+// 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()) {
@@ -306,6 +309,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   if (IsAndroid || Distro.IsOpenSUSE())
     ExtraOpts.push_back("--enable-new-dtags");
+#endif	// Guix
 
   // 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.
@@ -363,7 +367,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     // the cross. Note that GCC does include some of these directories in some
     // configurations but this seems somewhere between questionable and simply
     // a bug.
-    if (StringRef(LibPath).startswith(SysRoot)) {
+    if (0) {
       addPathIfExists(D, LibPath + "/" + MultiarchTriple, Paths);
       addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
     }
@@ -382,6 +386,8 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
   addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);
 
+// This requires the commented distro tweaks above.
+#if 0
   if (IsAndroid) {
     // Android sysroots contain a library directory for each supported OS
     // version as well as some unversioned libraries in the usual multiarch
@@ -410,10 +416,15 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     addPathIfExists(D, SysRoot + "/" + OSLibDir + "/" + ABIName, Paths);
     addPathIfExists(D, SysRoot + "/usr/" + OSLibDir + "/" + ABIName, Paths);
   }
+#endif
 
   // Try walking via the GCC triple path in case of biarch or multiarch GCC
   // installations with strange symlinks.
   if (GCCInstallation.isValid()) {
+
+// The following code would end up adding things like
+// "/usr/lib/x86_64-unknown-linux-gnu/../../lib64" to the search path.
+#if 0
     addPathIfExists(D,
                     SysRoot + "/usr/lib/" + GCCInstallation.getTriple().str() +
                         "/../../" + OSLibDir,
@@ -426,6 +437,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
                              BiarchSibling.gccSuffix(),
                       Paths);
     }
+#endif
 
     // See comments above on the multilib variant for details of why this is
     // included even from outside the sysroot.
@@ -450,8 +462,9 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   if (StringRef(D.Dir).startswith(SysRoot))
     addPathIfExists(D, D.Dir + "/../lib", Paths);
 
-  addPathIfExists(D, SysRoot + "/lib", Paths);
-  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
+  // 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);
 }
 
 ToolChain::CXXStdlibType Linux::GetDefaultCXXStdlibType() const {
fs.scm,
gnu/tests/package-management.scm, gnu/tests/reconfigure.scm,
gnu/tests/rsync.scm, gnu/tests/security-token.scm,
gnu/tests/singularity.scm, gnu/tests/ssh.scm, gnu/tests/telephony.scm,
gnu/tests/version-control.scm, gnu/tests/virtualization.scm,
gnu/tests/web.scm: Remove (mkdir #$output) (chdir #$output) and
pass #$output as argument to 'system-test-runner'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-09-25 18:52:05 +0200'>2021-09-25</span></td><td><a href='/guix/commit/gnu/tests/audio.scm?id=1fb75128a5202b406622da6272bc809c46d1f439'>tests: Adjust to SRFI-64 as found in Guile 3.0.7.</a><span class='msg-avail'>...<span class='msg-tooltip'>In Guile 3.0.7, 'test-runner-current' is set to #f upon 'test-end'.
Consequently, the previous strategy, where we'd call
'test-runner-current' after 'test-end', no longer works.  Instead, set
the test runner in each test right before 'test-begin'.

* gnu/build/marionette.scm (system-test-runner): New procedure.
* gnu/tests/audio.scm (run-mpd-test): Replace (exit (= ...)) idiom
by (test-runner-current (system-test-runner)).
* gnu/tests/base.scm (run-basic-test)
(run-cleanup-test, run-mcron-test, run-nss-mdns-test): Likewise.
* gnu/tests/ci.scm (run-laminar-test): Likewise.
* gnu/tests/cups.scm (run-cups-test): Likewise.
* gnu/tests/databases.scm (run-memcached-test)
(run-postgresql-test, run-mysql-test): Likewise.
* gnu/tests/desktop.scm (run-elogind-test): Likewise.
* gnu/tests/dict.scm (run-dicod-test): Likewise.
* gnu/tests/docker.scm (run-docker-test): Likewise.
(run-docker-system-test): Likewise.
* gnu/tests/file-sharing.scm (run-transmission-daemon-test): Likewise.
* gnu/tests/ganeti.scm (run-ganeti-test): Likewise.
* gnu/tests/guix.scm (run-guix-build-coordinator-test): Likewise.
(run-guix-data-service-test): Likewise.
* gnu/tests/ldap.scm (run-ldap-test): Likewise.
* gnu/tests/linux-modules.scm (run-loadable-kernel-modules-test-base): Likewise.
* gnu/tests/mail.scm (run-opensmtpd-test)
(run-exim-test, run-dovecot-test, run-getmail-test): Likewise.
* gnu/tests/messaging.scm (run-xmpp-test)
(run-bitlbee-test, run-quassel-test): Likewise.
* gnu/tests/monitoring.scm (run-prometheus-node-exporter-server-test)
(run-zabbix-server-test): Likewise.
* gnu/tests/networking.scm (run-inetd-test, run-openvswitch-test)
(run-dhcpd-test, run-tor-test, run-iptables-test, run-ipfs-test): Likewise.
* gnu/tests/nfs.scm (run-nfs-test)
(run-nfs-server-test, run-nfs-root-fs-test): Likewise.
* gnu/tests/package-management.scm (run-nix-test): Likewise.
* gnu/tests/reconfigure.scm (run-switch-to-system-test)
(run-upgrade-services-test, run-install-bootloader-test): Likewise.
* gnu/tests/rsync.scm (run-rsync-test): Likewise.
* gnu/tests/security-token.scm (run-pcscd-test): Likewise.
* gnu/tests/singularity.scm (run-singularity-test): Likewise.
* gnu/tests/ssh.scm (run-ssh-test): Likewise.
* gnu/tests/telephony.scm (run-jami-test): Likewise.
* gnu/tests/version-control.scm (run-cgit-test): Likewise.
(run-git-http-test, run-gitolite-test, run-gitile-test): Likewise.
* gnu/tests/virtualization.scm (run-libvirt-test, run-childhurd-test): Likewise.
* gnu/tests/web.scm (run-webserver-test, run-php-fpm-test)
(run-hpcguix-web-server-test, run-tailon-test, run-patchwork-test): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-06 23:14:14 +0100'>2020-11-06</span></td><td><a href='/guix/commit/gnu/tests/audio.scm?id=9909eddbc55c6cac5acccab453993cd113aa38a1'>tests: mpd: Remove race condition; use default MPD configuration.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/audio.scm (%mpd-os): Use the default 'mpd-configuration'.
(run-mpd-test)[test]("mpd listening"): New test.
("mpc connect"): Use 'system*' and 'test-equal'.
</span></span></td><td>Ludovic Courtès</td></tr>