Fix E0044: Non-Const Item in Const Context

Wed, 05 Aug 2026 10:20:04 +0800

1. Symptoms

When the Rust compiler encounters E0044, you will see an error message similar to the following in your build output:

error[E0044]: non-constant item in a constant item
  --> src/main.rs:5:5
   |
5  |     static STREAM: Stream = Stream::new();
   |              ^^^^^^ non-constant item

Another common manifestation appears when attempting to use non-const functions within constant contexts:

error[E0044]: non-constant item in a constant item
  --> src/lib.rs:12:8
   |
12 | const VALUE: i32 = compute_value();
   |                  ^^^^^^^^^^^^^ non-constant item

The error specifically indicates that the compiler found a non-constant item where a constant expression was required. This happens during the const-evaluation phase of compilation, where Rust attempts to evaluate expressions at compile time rather than runtime. The compiler rejects these constructs because it cannot guarantee that the referenced items will be deterministically computable during compilation, which is essential for constant evaluation.

E0044 on ErrorVault — Developer Error Code Dictionary

Fix E0044: Non-Const Item in Const Context

1. Symptoms