Fix E0791: Dereference of Raw Pointer in Const Fn

Tue, 11 Aug 2026 07:56:04 +0800

1. Symptoms

The Rust compiler emits error E0791 when it encounters raw pointer dereference operations within a const fn context. This error manifests during compilation and prevents the program from building successfully.

When triggered, the compiler produces output similar to the following:

error[E0791]: dereference of raw pointer in const fn
 --> src/main.rs:4:5
  |
4 |     const fn read_value(ptr: *const i32) -> i32 {
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ const fn
...
7 |         unsafe { *ptr }
  |                  ^^^^^^ raw pointer dereference
  |
  = note: const ptr arithmetic is not stable yet
  = note: see issue #71313 <https://github.com/rust-lang/rust/issues/71313> for more information

error: aborting due to 1 previous error

The error message specifically identifies the raw pointer dereference operation (*ptr) and clarifies that the offending function is a const fn. The compiler also references an upstream tracking issue in the Rust repository, indicating this is a limitation of the current stable compiler rather than a fundamental language design choice.

E0791 on ErrorVault — Developer Error Code Dictionary

Fix E0791: Dereference of Raw Pointer in Const Fn

1. Symptoms