---
title: "[RFC] [Discussion] Bound-Erased Generic Types"
url: https://daily.dev/posts/rfc-discussion-bound-erased-generic-types-su8puw4vm
source_url: https://externals.io/message/131164
type: article
source: "externals.io"
published: 2026-06-07T13:27:30.190Z
updated: 2026-06-07T13:32:06.201Z
tags: ["php"]
reading_time: 280
upvotes: 0
comments: 0
language: en
---

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# [RFC] [Discussion] Bound-Erased Generic Types

**[externals.io](https://daily.dev/sources/externals)** · 280 min read · 0 upvotes · 0 comments

## Summary

A PHP internals mailing list thread discussing a new RFC proposing bound-erased generic types for PHP. The RFC proposes generic type parameters on classes, interfaces, traits, functions, methods, closures, and arrow functions with bounds, defaults, and variance markers. Type parameters erase to their bound at runtime, with pre-erasure form preserved for Reflection and static analyzers. Key discussion points include: ordering restrictions for mutually-recursive type bounds, intersection type restrictions with unbounded type parameters, arity validation being opt-in via turbofish syntax, diamond inheritance checks, turbofish syntax vs alternatives, +/- variance markers vs in/out keywords, and the path toward future reified/runtime generics.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://externals.io/message/131164>

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