Merge #25

25: Fix caching r=roberth a=roberth

I hope this is acceptable because it already took too many iterations imo.
:rabbit: 
:hole: 

Co-authored-by: Robert Hensing <[email protected]>

Author: bors[bot]

.pre-commit-config.yaml

@@ -12,7 +12,7 @@
           "id": "shellcheck"
         }
       ],
-      "repo": ".pre-commit-hooks/",
+      "repo": ".pre-commit-hooks",
       "rev": "master"
     }
   ]

modules/pre-commit.nix

@@ -179,6 +179,20 @@ let
   inherit (import (import ../nix/sources.nix).gitignore { inherit lib; })
     gitignoreSource
     ;
+
+  patch =
+    pre-commit:
+      pre-commit.overrideAttrs (
+        drv:
+          {
+            patches =
+              (drv.patches or []) ++ [
+              ../nix/pre-commit-resolve-symlink.patch
+            ];
+            name = "${drv.name}-nix";
+          }
+      );
+
 in {
   options.pre-commit =
     {
@@ -190,10 +204,10 @@ in {
             ''
               The pre-commit package to use.
             '';
-          default = pkgs.pre-commit;
+          default = patch pkgs.pre-commit;
           defaultText =
             literalExample ''
-              pkgs.pre-commit
+              patch pkgs.pre-commit
             '';
         };
 
@@ -289,7 +303,7 @@ in {
         repos =
           [
             {
-              repo = ".pre-commit-hooks/";
+              repo = ".pre-commit-hooks";
               rev = "master";
               hooks =
                 mapAttrsToList ( id: _value: { inherit id; } ) enabledHooks;
@@ -338,9 +352,10 @@ in {
             fi
 
             if $doInstall; then
-              pre-commit install
-              # this is needed as the hook repo configuration is cached
+              # This because we're still using a clone. The clean invocation can
+              # be rid of when the patch uses a *working* non-clone code path.
               pre-commit clean
+              pre-commit install
             fi
           fi
         '';

nix/pre-commit-resolve-symlink.patch

@@ -0,0 +1,33 @@
+diff --git a/pre_commit/repository.py b/pre_commit/repository.py
+index 3042f12..16ad603 100644
+--- a/pre_commit/repository.py
++++ b/pre_commit/repository.py
+@@ -195,11 +195,27 @@ def _cloned_repository_hooks(repo_config, store, root_config):
+     )
+ 
+ 
++def _adapt_for_external_cache(repo_config):
++    if os.path.exists(repo_config['repo']) and os.path.islink(repo_config['repo']):
++        target = os.readlink(repo_config['repo'])
++        if target.startswith("/nix/store/"):
++            repo_config['repo'] = target
++            return True
++        else:
++            return False
++    else:
++        return False
++
++
+ def _repository_hooks(repo_config, store, root_config):
+     if repo_config['repo'] in {LOCAL, META}:
+         return _non_cloned_repository_hooks(repo_config, store, root_config)
+     else:
+-        return _cloned_repository_hooks(repo_config, store, root_config)
++        if _adapt_for_external_cache(repo_config):
++            # No real need to clone, but _non_cloned seems to be broken...
++            return _cloned_repository_hooks(repo_config, store, root_config)
++        else:
++            return _cloned_repository_hooks(repo_config, store, root_config)
+ 
+ 
+ def install_hook_envs(hooks, store):