Add initial support for building with extensions

flake.nix

@@ -22,7 +22,7 @@
         enableDebug = [ true false ];
         enableInteractive = [ true false ];
       };
-    in lib.mergeAttrsList (lib.mapCartesianProduct (args@{
+    in lib.mergeAttrsList (lib.mapCartesianProduct ({
       enableMinimal,
       enableDebug,
       enableInteractive,
@@ -35,11 +35,60 @@
           enableInteractive;
       };
     in {
-      "sqlite${result.suffix}" = result.sqlite;
-      "sqlite-amalgamation${result.suffix}" = result.amalgamation;
-      "sqlite-cli${result.suffix}" = result.sqlite-cli;
-      "sqlite-static${result.suffix}" = result.sqlite-static;
+      "sqlite${result._suffix}" = result.sqlite;
+      "sqlite-amalgamation${result._suffix}" = result.amalgamation;
+      "sqlite-cli${result._suffix}" = result.sqlite-cli;
+      "sqlite-static${result._suffix}" = result.sqlite-static;
     }) productVars));
+
+    checks = forAllSystems (system: pkgs: let
+      sqlite-example-exts-static = pkgs.stdenv.mkDerivation {
+        name = "sqlite-example-exts-static";
+        src = ./sqlite-example-exts;
+
+        env.NIX_CFLAGS_COMPILE = "-DSQLITE_CORE";
+
+        buildInputs = with pkgs; [ sqlite.dev ];
+        buildPhase = ''
+          runHook preBuild
+
+          "$CC" -c addext.c
+          "$AR" rcs libaddext.a addext.o
+
+          "$CC" -c subext.c
+          "$AR" rcs libsubext.a subext.o
+
+          runHook postBuild
+        '';
+
+
+        installPhase = ''
+          runHook preInstall
+
+          install -Dm444 *.a -t "$out/lib"
+
+          runHook postInstall
+        '';
+      };
+
+      sqlite-with-static-exts = self.mkSqlite {
+        inherit pkgs;
+
+        extensions = [
+          {
+            library = "${sqlite-example-exts-static}/lib/libaddext.a";
+            init = "sqlite3_addext_init";
+          }
+          {
+            library = "${sqlite-example-exts-static}/lib/libsubext.a";
+            init = "sqlite3_subext_init";
+          }
+        ];
+      };
+    in {
+      inherit sqlite-example-exts-static;
+      sqlite-with-static-ext = sqlite-with-static-exts.sqlite;
+      sqlite-cli-with-static-ext = sqlite-with-static-exts.sqlite-cli;
+    });
   };
 }
-