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-GuixSD systems.

This patch makes slight adjustments over "clang-libc-search-path.patch" for
changes in clang 3.8.

--- cfe-3.8.0.src/lib/Driver/ToolChains.cpp
+++ cfe-3.8.0.src/lib/Driver/ToolChains.cpp
@@ -3661,6 +3661,9 @@
                          GCCInstallation.getTriple().str() + "/bin")
                        .str());
 
+  // Comment out the distro-specific tweaks so that they don't bite when
+  // using Guix on a foreign distro.
+#if 0
   Distro Distro = DetectDistro(D, Arch);
 
   if (IsOpenSUSE(Distro) || IsUbuntu(Distro)) {
@@ -3702,6 +3705,7 @@
 
   if (IsOpenSUSE(Distro))
     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.
@@ -3771,14 +3775,12 @@
     addPathIfExists(D, D.Dir + "/../" + OSLibDir, Paths);
   }
 
-  addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
-  addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);
-  addPathIfExists(D, SysRoot + "/usr/lib/" + MultiarchTriple, Paths);
-  addPathIfExists(D, SysRoot + "/usr/lib/../" + OSLibDir, Paths);
-
   // 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,
@@ -3791,6 +3793,7 @@
                              BiarchSibling.gccSuffix(),
                       Paths);
     }
+#endif
 
     // See comments above on the multilib variant for details of why this is
     // included even from outside the sysroot.
@@ -3815,8 +3818,9 @@
   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);
 }
 
 bool Linux::HasNativeLLVMSupport() const { return true; }
200'>2023-10-12</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=8b8ab17561cad10ce2b613ece8e8cdfba729fc1a'>accounts: Fix typo in comment.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/accounts.scm (passwd-&gt;shadow): Fix typo in comment.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-10-08 23:43:49 +0200'>2023-10-08</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=002c5bec07e88c00d9d96209438728d0271f57da'>accounts: Ensure ‘last-change’ field of shadow entries is never zero.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/accounts.scm (passwd-&gt;shadow): Add ‘max’ call so NOW is
greater than or equal to 1.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-01-01 15:10:12 +0100'>2022-01-01</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=671e6a81804f264ddcdd6fe7579644404da079b8'>system: Allow 'chfn' to change the user's full name.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/52539&gt;.
Reported by Jacob First &lt;jacob.first@member.fsf.org&gt;.

* gnu/build/accounts.scm (allocate-passwd): Add comment as to why
'real-name' is taken from PREVIOUS.  Add (not system?) to the
condition.
* gnu/system.scm (operating-system-etc-service) &lt;login.defs&gt;: Add
"CHFN_RESTRICT".
* gnu/system.scm (%setuid-programs): Add "chfn".
* gnu/system/pam.scm (base-pam-services): Add "chfn".
* doc/guix.texi (User Accounts): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>