fix wrong comment

fixes #66

COPYING

@@ -0,0 +1,20 @@
+Copyright (c) 2020-2021 Eelco Dolstra and the flake-compat contributors
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -0,0 +1,41 @@
+# flake-compat
+
+## Usage
+
+> [!WARNING]
+> During the Lix private beta period during which Forgejo is private, this
+> requires configuring netrc in Lix for the tarball download to work.
+>
+> Your netrc should look something like so:
+> ```
+> machine git.lix.systems login YOUR-USERNAME password SOME-PERSONAL-ACCESS-TOKEN-REPO-READ
+> ```
+>
+> We are terribly sorry for the UX for this being very bad
+> ([issue](https://git.lix.systems/lix-project/lix/issues/254)).
+
+To use, add the following to your `flake.nix`:
+
+<!-- FIXME: this can use the standard non-api archive url when we are
+un-privated -->
+
+```nix
+inputs.flake-compat.url = "https://git.lix.systems/api/v1/repos/lix-project/flake-compat/archive/main.tar.gz";
+```
+
+Afterwards, create a `default.nix` file containing the following:
+
+```nix
+(import
+  (
+    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = lock.nodes.flake-compat.locked.url;
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  { src = ./.; }
+).defaultNix
+```
+
+If you would like a `shell.nix` file, create one containing the above, replacing `defaultNix` with `shellNix`.

default.nix

@@ -16,7 +16,11 @@ let
   fetchTree =
     info:
     if info.type == "github" then
-      { outPath = fetchTarball "https://api.${info.host or "github.com"}/repos/${info.owner}/${info.repo}/tarball/${info.rev}";
+      { outPath =
+          fetchTarball
+            ({ url = "https://api.${info.host or "github.com"}/repos/${info.owner}/${info.repo}/tarball/${info.rev}"; }
+             // (if info ? narHash then { sha256 = info.narHash; } else {})
+            );
         rev = info.rev;
         shortRev = builtins.substring 0 7 info.rev;
         lastModified = info.lastModified;
@@ -29,28 +33,47 @@ let
             ({ url = info.url; }
              // (if info ? rev then { inherit (info) rev; } else {})
              // (if info ? ref then { inherit (info) ref; } else {})
+             // (if info ? submodules then { inherit (info) submodules; } else {})
             );
-        rev = info.rev;
-        shortRev = builtins.substring 0 7 info.rev;
         lastModified = info.lastModified;
         lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
         narHash = info.narHash;
-      }
+      } // (if info ? rev then {
+        rev = info.rev;
+        shortRev = builtins.substring 0 7 info.rev;
+      } else {
+      })
     else if info.type == "path" then
       { outPath = builtins.path { path = info.path; };
         narHash = info.narHash;
       }
     else if info.type == "tarball" then
-      { outPath = fetchTarball info.url;
-        narHash = info.narHash;
+      { outPath =
+          fetchTarball
+            ({ inherit (info) url; }
+             // (if info ? narHash then { sha256 = info.narHash; } else {})
+            );
       }
     else if info.type == "gitlab" then
       { inherit (info) rev narHash lastModified;
-        outPath = fetchTarball "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}";
+        outPath =
+          fetchTarball
+            ({ url = "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}"; }
+             // (if info ? narHash then { sha256 = info.narHash; } else {})
+            );
+        shortRev = builtins.substring 0 7 info.rev;
+      }
+    else if info.type == "sourcehut" then
+      { inherit (info) rev narHash lastModified;
+        outPath =
+          fetchTarball
+            ({ url = "https://${info.host or "git.sr.ht"}/${info.owner}/${info.repo}/archive/${info.rev}.tar.gz"; }
+             // (if info ? narHash then { sha256 = info.narHash; } else {})
+            );
         shortRev = builtins.substring 0 7 info.rev;
       }
     else
-      # FIXME: add Mercurial, tarball inputs.
+      # FIXME: add Mercurial inputs.
       throw "flake input has unsupported input type '${info.type}'";
 
   callFlake4 = flakeSrc: locks:
@@ -78,15 +101,32 @@ let
     # tree is a valid git repository.
     tryFetchGit = src:
       if isGit && !isShallow
-      then builtins.fetchGit src
-      else { outPath = src; };
+      then
+        let res = builtins.fetchGit src;
+        in if res.rev == "0000000000000000000000000000000000000000" then removeAttrs res ["rev" "shortRev"]  else res
+      else {
+        outPath =
+          # Massage `src` into a store path.
+          if builtins.isPath src
+          then
+            if dirOf (toString src) == builtins.storeDir
+              # `builtins.storePath` is not available in pure-eval mode.
+              && builtins ? currentSystem
+            then
+              # If it's already a store path, don't copy it again.
+              builtins.storePath src
+            else
+              "${src}"
+          else
+            src;
+      };
     # NB git worktrees have a file for .git, so we don't check the type of .git
     isGit = builtins.pathExists (src + "/.git");
     isShallow = builtins.pathExists (src + "/.git/shallow");
 
   in
-    (if src ? outPath then src else tryFetchGit src)
-    // { lastModified = 0; lastModifiedDate = formatSecondsSinceEpoch 0; };
+    { lastModified = 0; lastModifiedDate = formatSecondsSinceEpoch 0; }
+      // (if src ? outPath then src else tryFetchGit src);
 
   # Format number of seconds in the Unix epoch as %Y%m%d%H%M%S.
   formatSecondsSinceEpoch = t:
@@ -124,7 +164,9 @@ let
 
           subdir = if key == lockFile.root then "" else node.locked.dir or "";
 
-          flake = import (sourceInfo + (if subdir != "" then "/" else "") + subdir + "/flake.nix");
+          outPath = sourceInfo + ((if subdir == "" then "" else "/") + subdir);
+
+          flake = import (outPath + "/flake.nix");
 
           inputs = builtins.mapAttrs
             (inputName: inputSpec: allNodes.${resolveInput inputSpec})
@@ -151,7 +193,21 @@ let
 
           outputs = flake.outputs (inputs // { self = result; });
 
-          result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
+          result =
+            outputs
+            # We add the sourceInfo attribute for its metadata, as they are
+            # relevant metadata for the flake. However, the outPath of the
+            # sourceInfo does not necessarily match the outPath of the flake,
+            # as the flake may be in a subdirectory of a source.
+            # This is shadowed in the next //
+            // sourceInfo
+            // {
+              # This shadows the sourceInfo.outPath
+              inherit outPath;
+
+              inherit inputs; inherit outputs; inherit sourceInfo; _type = "flake";
+            };
+
         in
           if node.flake or true then
             assert builtins.isFunction flake.outputs;
@@ -173,10 +229,12 @@ let
 in
   rec {
     defaultNix =
-      result
-      // (if result ? defaultPackage.${system} then { default = result.defaultPackage.${system}; } else {});
+      (builtins.removeAttrs result ["__functor"])
+      // (if result ? defaultPackage.${system} then { default = result.defaultPackage.${system}; } else {})
+      // (if result ? packages.${system}.default then { default = result.packages.${system}.default; } else {});
 
     shellNix =
       defaultNix
-      // (if result ? devShell.${system} then { default = result.devShell.${system}; } else {});
+      // (if result ? devShell.${system} then { default = result.devShell.${system}; } else {})
+      // (if result ? devShells.${system}.default then { default = result.devShells.${system}.default; } else {});
   }

flake.nix

@@ -0,0 +1,6 @@
+{
+  description = "Allow flakes to be used with Nix < 2.4";
+
+  outputs = { self }: {
+  };
+}