[ffigen] Generate build.dart script if a .m file is generated

[liamappelbe]

The main design goal is that the script should be composable. It should be easy for the user to integrate the new build stuff with their existing build script if they have one.

[brianquinlan]

@brianquinlan

[dcharkes]

The main design goal is that the script should be composable.

I'd suggest something along the lines of:

hook/build.dart

import 'package:hooks/hooks.dart';
import 'package:sqlite/src/ffigen_build.g.dart';

void main(List<String> args) async {
  await build(args, (input, output) async {
    await buildFfiGenAsset(input, output);
  });
}

lib/src/ffigen_build.g.dart:

// GENERATED BY FFIGEN DO NOT EDIT.

import 'package:code_assets/code_assets.dart';
import 'package:hooks/hooks.dart';
import 'package:native_toolchain_c/native_toolchain_c.dart';

Future<void> buildFfiGenAsset(
  BuildInput input,
  BuildOutputBuilder output,
) async {
  if (input.config.buildCodeAssets) {
    final builder = CBuilder.library(
      // ...
    );
    await builder.run(input: input, output: output);
  }
}

And throw an error if there's no call await buildFfiGenAsset(input, output); in hook/build.dart but it does exist.