message: double negation
diff: @@ -78,7 +78,7 @@ fn do_read_manifest(
  let (mut manifest, paths) =
  TomlManifest::to_real_manifest(&manifest, source_id, package_root, config)?;
  add_unused(manifest.warnings_mut());
  - if !manifest.targets().iter().any(|t| !t.is_custom_build()) {
  + if manifest.targets().iter().all(|t| t.is_custom_build()) {
  bail!(
  "no targets specified in the manifest\n \
  either src/lib.rs, src/main.rs, a [lib] section, or \
  