nix: Provide lib in flakes with buildPgxExtension

.gitignore

@@ -1,6 +1,6 @@
 .DS_Store
 .idea/
-/target
+target/
 *.iml
 **/*.rs.bk
 *.o

flake.nix

@@ -15,39 +15,33 @@
     let
       supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
       forAllSystems = f: nixpkgs.lib.genAttrs supportedSystems (system: f system);
-    in
-    {
-      defaultPackage = forAllSystems (system: (import nixpkgs {
+      supportedPostgresVersions = [ 10 11 12 13 14 ];
+      nixpkgsWithOverlays = { system, nixpkgs, extraOverlays ? [ ] }: (import nixpkgs {
         inherit system;
         overlays = [
           self.overlay
           rust-overlay.overlay
-          (self: super:
-            {
-              rustc = self.rust-bin.stable.latest.rustc;
-              cargo = self.rust-bin.stable.latest.cargo;
-              rustdoc = self.rust-bin.stable.latest.rustdoc;
-            }
-          )
-        ];
-      }).cargo-pgx);
+          (self: super: { inherit (self.rust-bin.stable.latest) rustc cargo rustdoc; })
+        ] ++ extraOverlays;
+      });
+      releaseAndDebug = attr: call: args: {
+        "${attr}" = call args;
+        "${attr}_debug" = call (args // { release = false; });
+      };
+    in
+    {
+      lib = {
+        inherit supportedSystems supportedPostgresVersions forAllSystems nixpkgsWithOverlays;
+        buildPgxExtension = { pkgs, source, pgxPostgresVersion, release ? true }: pkgs.callPackage ./nix/extension.nix {
+          inherit source pgxPostgresVersion release naersk;
+          inherit (gitignore.lib) gitignoreSource;
+        };
+      };
+      defaultPackage = forAllSystems (system: (nixpkgsWithOverlays { inherit system nixpkgs; }).cargo-pgx);
 
       packages = forAllSystems (system:
         let
-          pkgs = import nixpkgs {
-            inherit system;
-            overlays = [
-              self.overlay
-              rust-overlay.overlay
-              (self: super:
-                {
-                  rustc = self.rust-bin.stable.latest.rustc;
-                  cargo = self.rust-bin.stable.latest.cargo;
-                  rustdoc = self.rust-bin.stable.latest.rustdoc;
-                }
-              )
-            ];
-          };
+          pkgs = nixpkgsWithOverlays { inherit system nixpkgs; };
         in
         {
           inherit (pkgs) cargo-pgx;
@@ -67,20 +61,7 @@
 
       devShell = forAllSystems (system:
         let
-          pkgs = import nixpkgs {
-            inherit system;
-            overlays = [
-              self.overlay
-              rust-overlay.overlay
-              (self: super:
-                {
-                  rustc = self.rust-bin.stable.latest.rustc;
-                  cargo = self.rust-bin.stable.latest.cargo;
-                  rustdoc = self.rust-bin.stable.latest.rustdoc;
-                }
-              )
-            ];
-          };
+          pkgs = nixpkgsWithOverlays { inherit system nixpkgs; };
         in
         pkgs.mkShell {
           inputsFrom = with pkgs; [
@@ -112,20 +93,7 @@
 
       checks = forAllSystems (system:
         let
-          pkgs = import nixpkgs {
-            inherit system;
-            overlays = [
-              self.overlay
-              rust-overlay.overlay
-              (self: super:
-                {
-                  rustc = self.rust-bin.stable.latest.rustc;
-                  cargo = self.rust-bin.stable.latest.cargo;
-                  rustdoc = self.rust-bin.stable.latest.rustdoc;
-                }
-              )
-            ];
-          };
+          pkgs = nixpkgsWithOverlays { inherit system nixpkgs; };
         in
         {
           format = pkgs.runCommand "check-format"

nix/templates/default/default.nix → nix/extension.nix

@@ -22,6 +22,8 @@
 , gitignoreSource
 , pgxPostgresVersion ? 11
 , release ? true
+, source ? ./.
+, runCommand
 }:
 
 let
@@ -34,15 +36,15 @@ let
     else null;
   maybeReleaseFlag = if release == true then "--release" else "";
   pgxPostgresVersionString = builtins.toString pgxPostgresVersion;
-  cargoToml = (builtins.fromTOML (builtins.readFile ./Cargo.toml));
+  cargoToml = (builtins.fromTOML (builtins.readFile "${source}/Cargo.toml"));
 in
 
 naersk.lib."${targetPlatform.system}".buildPackage rec {
   inherit release;
   name = "${cargoToml.package.name}-pg${pgxPostgresVersionString}";
   version = cargoToml.package.version;
 
-  src = gitignoreSource ./.;
+  src = gitignoreSource source;
 
   inputsFrom = [ postgresql_10 postgresql_11 postgresql_12 postgresql_13 cargo-pgx ];