gnu: Remove clang-6.

* gnu/packages/llvm.scm (clang-6): Delete variable.
* gnu/packages/patches/clang-6.0-libc-search-path.patch: Delete file.
* gnu/local.mk (dist_patch_DATA): Unregister file.

Change-Id: Ife89d032bd5edbbc2613dbef71e5e8434d75c979

gnu/local.mk

@@ -1093,7 +1093,6 @@ dist_patch_DATA =						\
   %D%/packages/patches/clang-3.5-libc-search-path.patch		\
   %D%/packages/patches/clang-3.5-libsanitizer-ustat-fix.patch	\
   %D%/packages/patches/clang-3.8-libc-search-path.patch		\
-  %D%/packages/patches/clang-6.0-libc-search-path.patch		\
   %D%/packages/patches/clang-11.0-libc-search-path.patch	\
   %D%/packages/patches/clang-12.0-libc-search-path.patch	\
   %D%/packages/patches/clang-13.0-libc-search-path.patch	\

gnu/packages/llvm.scm

@@ -1056,12 +1056,6 @@ Library.")
    '("clang-runtime-9-libsanitizer-mode-field.patch"
      "clang-runtime-9-glibc-2.36-compat.patch")))
 
-(define-public clang-6
-  (clang-from-llvm llvm-6 clang-runtime-6
-                   "0rxn4rh7rrnsqbdgp4gzc8ishbkryhpl1kd3mpnxzpxxhla3y93w"
-                   #:legacy-build-shared-libs? #t
-                   #:patches '("clang-6.0-libc-search-path.patch")))
-
 (define-public llvm-3.8
   (package (inherit llvm-6)
     (name "llvm")

gnu/packages/patches/clang-6.0-libc-search-path.patch

@@ -1,67 +0,0 @@
-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.
-
---- cfe-6.0.0.src/lib/Driver/ToolChains/Linux.cpp
-+++ cfe-6.0.0.src/lib/Driver/ToolChains/Linux.cpp
-@@ -207,7 +207,9 @@
-   PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
-                          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(D.getVFS());
- 
-   if (Distro.IsAlpineLinux()) {
-@@ -255,6 +257,7 @@
- 
-   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.
-@@ -329,14 +332,12 @@
-     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,
-@@ -349,6 +350,7 @@
-                              BiarchSibling.gccSuffix(),
-                       Paths);
-     }
-+#endif
- 
-     // See comments above on the multilib variant for details of why this is
-     // included even from outside the sysroot.
-@@ -373,8 +375,9 @@
-   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; }