Merge pull request 'Update readme' (#67) from cobaltcause/flake-compat:readme into main

Reviewed-on: #67

README.md

@@ -6,7 +6,8 @@ To use, add the following to your `flake.nix`:
 
 ```nix
 inputs.flake-compat = {
-  url = github:edolstra/flake-compat;
+  url = "git+https://git.lix.systems/lix-project/flake-compat";
+  # Optional:
   flake = false;
 };
 ```
@@ -16,10 +17,13 @@ Afterwards, create a `default.nix` file containing the following:
 ```nix
 (import
   (
-    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
-    fetchTarball {
-      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
-      sha256 = lock.nodes.flake-compat.locked.narHash;
+    let
+      lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+      inherit (lock.nodes.flake-compat.locked) narHash rev url;
+    in
+    builtins.fetchTarball {
+      url = "${url}/archive/${rev}.tar.gz";
+      sha256 = narHash;
     }
   )
   { src = ./.; }

default.nix

@@ -33,6 +33,7 @@ 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 {})
             );
         lastModified = info.lastModified;
         lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
@@ -62,8 +63,17 @@ let
             );
         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:
@@ -94,7 +104,22 @@ let
       then
         let res = builtins.fetchGit src;
         in if res.rev == "0000000000000000000000000000000000000000" then removeAttrs res ["rev" "shortRev"]  else res
-      else { outPath = src; };
+      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");
@@ -139,7 +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})
@@ -166,7 +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;
@@ -187,11 +228,15 @@ let
 
 in
   rec {
+    inputs = result.inputs // { self = result; };
+
     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 }: {
+  };
+}