Clang tidy include cleaner

.clang-tidy

@@ -1,3 +1,5 @@
 # We use pointers to aggregates in a couple of places, intentionally.
 # void * would look weird.
-Checks: '-bugprone-sizeof-expression'
+Checks: '
+  -bugprone-sizeof-expression
+  '

doc/manual/source/development/building.md

@@ -291,6 +291,16 @@ To refresh pre-commit hook's config file, do the following:
 1. Exit the development shell and start it again by running `nix develop`.
 2. If you also use the pre-commit hook, also run `pre-commit-hooks-install` again.
 
+#### Hooks
+
+##### clang-tidy
+
+Portions of the codebase are checked with [clang-tidy](https://clang.llvm.org/extra/clang-tidy/).
+
+> clang-tidy is a clang-based C++ “linter” tool. 
+
+The current build system, Meson, by default outputs a `compile_commands.json` file which is used by all Clang tooling (clang-tidy, clangd etc..).
+
 ### VSCode
 
 Insert the following json into your `.vscode/settings.json` file to configure `nixfmt`.

maintainers/flake-module.nix

@@ -65,6 +65,20 @@
               ''^tests/functional/lang/eval-fail-set\.nix$''
             ];
           };
+          clang-tidy = {
+            enable = true;
+            # TODO: this requires meson to have been configured
+            # we could optionally wrap this in a script that runs meson first
+            # but for now let us keep it simple
+            #
+            # clang-tidy doesn't work well running it on multiple files
+            # TODO: change this to use run-clang-tidy.py
+            entry = "${pkgs.writeShellScript "clang-tidy-wrapper" ''
+              for file in "$@"; do
+              "${pkgs.clang-tools}/bin/clang-tidy" --fix -p ./build "$file"
+              done
+            ''}";
+          };
           clang-format = {
             enable = true;
             # https://github.com/cachix/git-hooks.nix/pull/532

src/libcmd/include/nix/cmd/repl.hh

@@ -11,7 +11,7 @@ struct AbstractNixRepl
     Bindings * autoArgs;
 
     AbstractNixRepl(ref<EvalState> state)
-        : state(state)
+        : state(state), autoArgs(nullptr)
     { }
 
     virtual ~AbstractNixRepl()