Compile-Time on ErrorVault — Developer Error Code Dictionary

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.

Fix E0714: Destructors Cannot Be Evaluated at Constant Expression Compilation

Fri, 07 Aug 2026 15:08:04 +0800

1. Symptoms

The Rust compiler emits error E0714 when you attempt to use a pattern involving types with destructors in a const or static item context where the destructor cannot be evaluated at compile time. The error manifests with a clear diagnostic message indicating that destructors are forbidden during constant evaluation.

When you encounter this error, the compiler produces output similar to the following:

error[E0714]: destructors cannot be evaluated at constant expression compilation
  --> src/main.rs:6:13
   |
6  | const VALUE: Option<Box<i32>> = Some(Box::new(42));
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: this error occurs in the expansion of static item initialization

The error points to the exact line where the problematic pattern appears, and the note clarifies that the issue occurs during static item initialization. In more complex scenarios involving tuple destructuring, you might see additional context about which part of the pattern triggered the evaluation:

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.

Fix E0531: Const Static Initializer Error in Rust

Mon, 03 Aug 2026 15:08:04 +0800

1. Symptoms

When Rust code triggers error E0531, the compiler produces diagnostic output indicating that a constant expression cannot be evaluated at compile time. The error manifests when attempting to initialize a const or static item with a value that requires runtime computation or contains non-constant operations.

The compiler displays the error with the following characteristics:

error[E0531]: const static initializer观摩会影响常量求值
 --> src/main.rs:X:Y
  |
X | const MY_CONST: u32 = some_function();
  |                    ^^^^^^^^^^^^^^^^^^^ cannot use a non-const function

Additional symptoms include:

Fix E0669: Non-const function call in const context

Sun, 02 Aug 2026 12:44:04 +0800

1. Symptoms

When you encounter error E0669, the Rust compiler produces output similar to the following:

error[E0669]: calls in constants are limited to inherent functions, structs, variants, and trait methods
  --> src/main.rs:6:5
   |
6  |     do_something();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The error message indicates that the function call cannot be evaluated at compile time because the called function lacks the const qualifier. The compiler explicitly states that constant evaluation contexts are restricted to inherent functions, struct constructors, enum variant constructors, and trait methods that have been marked as const.

Fix E0643: Generic Const Parameters Cannot Be Used in Function Body

Sat, 25 Jul 2026 00:44:04 +0800

Fix E0643: Generic Const Parameters Cannot Be Used in Function Body

Rust’s const generics feature enables writing code that is generic over constant values, allowing types like Vec<N> where N is a compile-time integer. However, the compiler imposes strict restrictions on what operations can be performed on const generic parameters inside function bodies. Error E0643 is emitted when a const generic parameter is used in a way that the compiler cannot evaluate at compile time, making it impossible to monomorphize the function for a given set of generic arguments.

Fix E0015: Cannot Call Non-Const Fn in Const Context

Thu, 23 Jul 2026 19:56:04 +0800

1. Symptoms

When your Rust code triggers error E0015, the compiler produces output similar to the following:

error[E0015]: cannot call non-const fn `some_function` in a constant
 --> src/main.rs:5:5
  |
5  |     some_function();
  |     ^^^^^^^^^^^^^^^
  |
  = note: non-const functions may only be called at runtime, in constant
    expressions in the right-hand side of `let` statements with no patterns

This error typically manifests when you attempt to use a runtime function inside a const context, whether that context is a const fn, a static variable, or a const variable declaration. The compiler explicitly rejects the operation because constant evaluation in Rust occurs entirely at compile time, and certain operations—including function calls that the compiler cannot evaluate—are not permitted in this phase.

Fix E0453: Overflow in Constant Evaluation

Sun, 19 Jul 2026 07:56:04 +0800

Fix E0453: Overflow in Constant Evaluation

Rust’s compile-time evaluation engine enforces strict arithmetic safety rules when computing constant expressions. When an operation would overflow during constant evaluation, the compiler emits error E0453. This error typically surfaces during const function calls, generic constant expressions, or array length computations where the result exceeds the representable range of the target integer type.

1. Symptoms

Error E0453 manifests during the compilation phase, specifically during the monomorphization or const evaluation passes. The compiler halts with a diagnostic message that pinpoints both the location of the overflow and the specific operation that caused it.

Fix E0080: Evaluation of Constant Value Failed

Wed, 10 Jun 2026 00:44:04 +0800

1. Symptoms

The Rust compiler produces error E0080 when it encounters a constant expression that cannot be evaluated at compile time. This error manifests in several distinct ways that you should recognize.

Primary Error Message:

error[E0080]: evaluation of constant value failed –> src/main.rs:X:Y | X | const VALUE: Type = expression; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempt to compute value that was never initialized


**Common Variants:**

error[E0080]: evaluation of constant value failed –> src/main.rs:X:Y | X | const VALUE: u32 = 10 / 0; | ^ attempt to divide by zero

Fix E0711: Const Item Cannot Have a Destructor

Wed, 27 May 2026 19:56:04 +0800

1. Symptoms

When you attempt to create a const item with a type that implements Drop, the Rust compiler aborts with E0711.

error[E0711]: this is a `const` item, so it is part of the static lifetime and
               cannot have a destructor
  --> src/main.rs:5:1
   |
5  | const ITEM: SomeType = SomeType::new();
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: constants get deduplicated by the compiler, which is incompatible with Drop
help: consider using a `static` instead of a `const`
  |
12 | static ITEM: SomeType = SomeType::new();
   | ^^^^^^
---

The compiler explicitly tells you that:
1. Constants are part of the static lifetime
2. Constants get deduplicated (memory optimization)
3. Deduplication is incompatible with the `Drop` trait

A more specific error variant appears when the type implements `Drop` but the destructor never actually runs:

```console
error[E0711]: type `WrappingType` has a Drop impl, which is incompatible with const
  --> src/lib.rs:10:20
   |
10 | const VALUE: WrappingType = WrappingType { inner: 42 };
   |                    ^^^^^^^^^
   = note: `const` items may not have types that implement `Drop`

Common Error Variations

// Variation 1: Direct type with Drop
const MY_STRING: String = String::from("hello");
// error[E0711]: `String` doesn't implement `Copy`, and a const cannot have a `Drop` impl

// Variation 2: Struct with Drop impl
const MY_STRUCT: MyStruct = MyStruct { value: 0 };
// error[E0711]: this is a `const` item, so it is part of the static lifetime and cannot have a destructor

// Variation 3: Type alias to Drop type
type Alias = SomeDropType;
const THING: Alias = SomeDropType::new();
// error[E0711]: cannot have destructor

2. Root Cause

The E0711 error stems from fundamental differences between const and static items in Rust, combined with how Drop implementations work.