I was expecting that resolve.tsconfigFilename only affects resolution because the option is inside resolve. To make it worse, even when I set the related transform options, those were overridden without any warning, making the investigation difficult...

My proposal is to:

• rename resolve.tsconfigFilename to a top-level tsconfig option
• prefer the value set in the transform / resolve options if both values are set, also emit a warning
• (not directly related) port the tsconfig & transform option merging code from

  rolldown/crates/rolldown_plugin_transform/src/utils.rs

  Lines 142 to 244 in 0078e84

  	let compiler_options = &tsconfig.compiler_options;
  	// when both the normal options and tsconfig is set,
  	// we want to prioritize the normal options
  	if compiler_options.jsx.as_deref() == Some("preserve")
  	&& transform_options
  	.jsx
  	.as_ref()
  	.is_none_or(|jsx| matches!(jsx, Either::Right(right) if right.runtime.is_none()))
  	{
  	transform_options.jsx = Some(Either::Left(String::from("preserve")));
  	}
  	if !matches!(&transform_options.jsx, Some(Either::Left(left)) if left == "preserve") {
  	let mut jsx = if let Some(Either::Right(jsx)) = transform_options.jsx {
  	jsx
  	} else {
  	JsxOptions::default()
  	};
  	if compiler_options.jsx_factory.is_some() && jsx.pragma.is_none() {
  	jsx.pragma.clone_from(&compiler_options.jsx_factory);
  	}
  	if compiler_options.jsx_import_source.is_some() && jsx.import_source.is_none() {
  	jsx.import_source.clone_from(&compiler_options.jsx_import_source);
  	}
  	if compiler_options.jsx_fragment_factory.is_some() && jsx.pragma_frag.is_none() {
  	jsx.pragma_frag.clone_from(&compiler_options.jsx_fragment_factory);
  	}
  	if jsx.runtime.is_none() {
  	match compiler_options.jsx.as_deref() {
  	Some("react") => {
  	jsx.runtime = Some(String::from("classic"));
  	// this option should not be set when using classic runtime
  	jsx.import_source = None;
  	}
  	Some("react-jsx") => {
  	jsx.runtime = Some(String::from("automatic"));
  	// these options should not be set when using automatic runtime
  	jsx.pragma = None;
  	jsx.pragma_frag = None;
  	}
  	Some("react-jsxdev") => jsx.development = Some(true),
  	_ => {}
  	}
  	}
  	transform_options.jsx = Some(Either::Right(jsx));
  	}
  	if transform_options.decorator.as_ref().is_none_or(|decorator| decorator.legacy.is_none()) {
  	let mut decorator = transform_options.decorator.unwrap_or_default();
  	if compiler_options.experimental_decorators.is_some() {
  	decorator.legacy = compiler_options.experimental_decorators;
  	}
  	if compiler_options.emit_decorator_metadata.is_some() {
  	decorator.emit_decorator_metadata = compiler_options.emit_decorator_metadata;
  	}
  	transform_options.decorator = Some(decorator);
  	}
  	// | preserveValueImports | importsNotUsedAsValues | verbatimModuleSyntax | onlyRemoveTypeImports |
  	// | -------------------- | ---------------------- | -------------------- |---------------------- |
  	// | false | remove | false | false |
  	// | false | preserve, error | - | - |
  	// | true | remove | - | - |
  	// | true | preserve, error | true | true |
  	let mut typescript = transform_options.typescript.unwrap_or_default();
  	typescript.only_remove_type_imports = if compiler_options.verbatim_module_syntax.is_some() {
  	compiler_options.verbatim_module_syntax
  	} else if compiler_options.preserve_value_imports.is_some()
  	|| compiler_options.imports_not_used_as_values.is_some()
  	{
  	let preserve_value_imports = compiler_options.preserve_value_imports.unwrap_or(false);
  	let imports_not_used_as_values =
  	compiler_options.imports_not_used_as_values.as_deref().unwrap_or("remove");
  	if !preserve_value_imports && imports_not_used_as_values == "remove" {
  	Some(true)
  	} else if preserve_value_imports
  	&& (imports_not_used_as_values == "preserve" || imports_not_used_as_values == "error")
  	{
  	Some(false)
  	} else {
  	// warnings.push(
  	// `preserveValueImports=${preserveValueImports} + importsNotUsedAsValues=${importsNotUsedAsValues} is not supported by oxc.` +
  	// 'Please migrate to the new verbatimModuleSyntax option.',
  	// )
  	Some(false)
  	}
  	} else {
  	Some(false)
  	};
  	transform_options.typescript = Some(typescript);
  	let disable_use_define_for_class_fields = !compiler_options
  	.use_define_for_class_fields
  	.unwrap_or_else(|| is_use_define_for_class_fields(compiler_options.target.as_deref()));
  	let mut assumptions = transform_options.assumptions.unwrap_or_default();
  	assumptions.set_public_class_fields = Some(disable_use_define_for_class_fields);
  	transform_options.assumptions = Some(assumptions);

  to https://github.com/rolldown/rolldown/blob/0078e8415034198cf466b7647f81978f812ab5d9/crates/rolldown/src/bundler_builder.rs, which sets more options