src/vs/editor/contrib/format/format.ts/getRealAndSyntheticDocumentFormattersOrdered
export function getRealAndSyntheticDocumentFormattersOrdered(model: ITextModel): DocumentFormattingEditProvider[] {
	const result: DocumentFormattingEditProvider[] = [];
	const seen = new Set<string>();

	// (1) add all document formatter
	const docFormatter = DocumentFormattingEditProviderRegistry.ordered(model);
	for (const formatter of docFormatter) {
		result.push(formatter);
		if (formatter.extensionId) {
			seen.add(ExtensionIdentifier.toKey(formatter.extensionId));
		}
	}

	// (2) add all range formatter as document formatter (unless the same extension already did that)
	const rangeFormatter = DocumentRangeFormattingEditProviderRegistry.ordered(model);
	for (const formatter of rangeFormatter) {
		if (formatter.extensionId) {
			if (seen.has(ExtensionIdentifier.toKey(formatter.extensionId))) {
				continue;
			}
			seen.add(ExtensionIdentifier.toKey(formatter.extensionId));
		}
		result.push({
			displayName: formatter.displayName,
			extensionId: formatter.extensionId,
			provideDocumentFormattingEdits(model, options, token) {
				return formatter.provideDocumentRangeFormattingEdits(model, model.getFullModelRange(), options, token);
			}
		});
	}
	return result;
}