clang6Stdenv, clang-tools_6, clang_6, lld_6, lldb_6, llvm_6: remove

Remove all the aliases for `llvmPackages_6` except the `llvmPackages_6`
itself.

We can remove `llvmPackages_6` once last two users are gone:

- vimPlugins: #279576
- beignet: #279578

pkgs/top-level/aliases.nix

@@ -172,7 +172,7 @@ mapAliases ({
   cvs_fast_export = cvs-fast-export; # Added 2021-06-10
 
   # these are for convenience, not for backward compat and shouldn't expire
-  clang6Stdenv = lowPrio llvmPackages_6.stdenv;
+  clang6Stdenv = throw "clang6Stdenv has been removed from nixpkgs"; # Added 2024-01-08
   clang7Stdenv = throw "clang7Stdenv has been removed from nixpkgs"; # Added 2023-11-19
   clang8Stdenv = lowPrio llvmPackages_8.stdenv;
   clang9Stdenv = lowPrio llvmPackages_9.stdenv;
@@ -185,7 +185,9 @@ mapAliases ({
   clang16Stdenv = lowPrio llvmPackages_16.stdenv;
   clang17Stdenv = lowPrio llvmPackages_17.stdenv;
 
+  clang-tools_6  = throw "clang-tools_6 has been removed from nixpkgs"; # Added 2024-01-08
   clang-tools_7  = throw "clang-tools_7 has been removed from nixpkgs"; # Added 2023-11-19
+  clang_6  = throw "clang_6 has been removed from nixpkgs"; # Added 2024-01-08
   clang_7  = throw "clang_7 has been removed from nixpkgs"; # Added 2023-11-19
 
   ### D ###
@@ -595,9 +597,12 @@ mapAliases ({
   linuxPackages_testing_bcachefs = throw "'linuxPackages_testing_bcachefs' has been removed, please use 'linuxPackages_testing', or any other linux kernel with bcachefs support";
   linux_testing_bcachefs = throw "'linux_testing_bcachefs' has been removed, please use 'linux_testing', or any other linux kernel with bcachefs support";
 
+  lld_6 = throw "lld_6 has been removed from nixpkgs"; # Added 2024-01-08
   lld_7 = throw "lld_7 has been removed from nixpkgs"; # Added 2023-11-19
+  lldb_6 = throw "lldb_6 has been removed from nixpkgs"; # Added 2024-01-08
   lldb_7 = throw "lldb_7 has been removed from nixpkgs"; # Added 2023-11-19
   llvmPackages_7 = throw "llvmPackages_7 has been removed from nixpkgs"; # Added 2023-11-19
+  llvm_6 = throw "llvm_6 has been removed from nixpkgs"; # Added 2024-01-08
   llvm_7 = throw "llvm_7 has been removed from nixpkgs"; # Added 2023-11-19
 
   lobster-two = google-fonts; # Added 2021-07-22

pkgs/top-level/all-packages.nix

@@ -15614,7 +15614,6 @@ with pkgs;
   };
 
   clang = llvmPackages.clang;
-  clang_6  = llvmPackages_6.clang;
   clang_8  = llvmPackages_8.clang;
   clang_9  = llvmPackages_9.clang;
   clang_10 = llvmPackages_10.clang;
@@ -15628,10 +15627,6 @@ with pkgs;
 
   clang-tools = callPackage ../development/tools/clang-tools { };
 
-  clang-tools_6 = callPackage ../development/tools/clang-tools {
-    llvmPackages = llvmPackages_6;
-  };
-
   clang-tools_8 = callPackage ../development/tools/clang-tools {
     llvmPackages = llvmPackages_8;
   };
@@ -16570,7 +16565,6 @@ with pkgs;
   };
 
   lld = llvmPackages.lld;
-  lld_6 = llvmPackages_6.lld;
   lld_8 = llvmPackages_8.lld;
   lld_9 = llvmPackages_9.lld;
   lld_10 = llvmPackages_10.lld;
@@ -16583,7 +16577,6 @@ with pkgs;
   lld_17 = llvmPackages_17.lld;
 
   lldb = llvmPackages.lldb;
-  lldb_6 = llvmPackages_6.lldb;
   lldb_8 = llvmPackages_8.lldb;
   lldb_9 = llvmPackages_9.lldb;
   lldb_10 = llvmPackages_10.lldb;
@@ -16596,7 +16589,6 @@ with pkgs;
   lldb_17 = llvmPackages_17.lldb;
 
   llvm = llvmPackages.llvm;
-  llvm_6  = llvmPackages_6.llvm;
   llvm_8  = llvmPackages_8.llvm;
   llvm_9  = llvmPackages_9.llvm;
   llvm_10 = llvmPackages_10.llvm;