nixos-option: cleanup and linting

pkgs/tools/nix/nixos-option/.clang-tidy

@@ -0,0 +1,26 @@
+Checks:
+- bugprone-*
+# don't find them too problematic
+- -bugprone-easily-swappable-parameters
+- performance-*
+- modernize-*
+# doesn't improve readability much in this project
+- -modernize-use-trailing-return-type
+- readability-*
+# don't find them too problematic
+- -readability-identifier-length
+- -readability-magic-numbers
+- portability-*
+- concurrency-*
+- google-*
+- -google-readability-todo
+- misc-*
+# we maybe want to address this?
+- -misc-no-recursion
+- cppcoreguidelines-*
+- -cppcoreguidelines-avoid-magic-numbers
+# We could use std::reference_wrapper, but it's not super important
+- -cppcoreguidelines-avoid-const-or-ref-data-members
+UseColor: true
+CheckOptions:
+  misc-non-private-member-variables-in-classes.IgnoreClassesWithAllMemberVariablesBeingPublic: True

pkgs/tools/nix/nixos-option/.envrc

@@ -0,0 +1 @@
+use nix

pkgs/tools/nix/nixos-option/shell.nix

@@ -0,0 +1,7 @@
+with import ../../../.. { };
+nixos-option.overrideAttrs (old: {
+  nativeBuildInputs = old.nativeBuildInputs ++ [
+    # hiprio so that it has a higher priority than the default unwrapped clang tools from clang if our stdenv is based on clang
+    (lib.hiPrio pkgs.buildPackages.clang-tools)
+  ];
+})

pkgs/tools/nix/nixos-option/src/libnix-copy-paste.cc

@@ -2,11 +2,13 @@
 // Since they are not, copy/paste them here.
 // TODO: Delete these and use the ones in the library as they become available.
 
+#include <string_view>
 #include "libnix-copy-paste.hh"
-#include <nix/print.hh>                           // for Strings
+#include <nix/print.hh>
 
+// NOLINTBEGIN
 // From nix/src/nix/repl.cc
-bool isVarName(const std::string_view & s)
+bool isVarName(std::string_view s)
 {
     if (s.size() == 0) return false;
     if (nix::isReservedKeyword(s)) return false;
@@ -20,3 +22,4 @@ bool isVarName(const std::string_view & s)
             return false;
     return true;
 }
+// NOLINTEND

pkgs/tools/nix/nixos-option/src/libnix-copy-paste.hh

@@ -1,5 +1,5 @@
 #pragma once
 
-#include <nix/types.hh>
+#include <string_view>
 
-bool isVarName(const std::string_view & s);
+bool isVarName(std::string_view s);