Use-Statement on ErrorVault — Developer Error Code Dictionary

Fix E0090: Unresolved Import in Rust

Sat, 08 Aug 2026 19:56:04 +0800

1. Symptoms

When Rust encounters error E0090, the compiler produces output that clearly identifies which import statement cannot be resolved. The error message includes the exact line number and the problematic path that the compiler failed to find.

error[E0090]: unresolved import `module::submodule`
 --> src/main.rs:3:5
  |
3 | use module::submodule;
  |     ^^^^^^^^^^^^^^^^ could not find `submodule` in `module`

In more complex scenarios involving external crates, the error might indicate that a crate itself cannot be found:

error[E0090]: unresolved import `external_crate::some_module`
 --> src/lib.rs:5:12
  |
5 | use external_crate::some_module;
  |            ^^^^^^^^^^^ could not find `some_module` in `external_crate` which is not a direct dependency

The compiler may also suggest alternative paths or modules that exist when the exact path cannot be resolved. When the import refers to a non-existent item within an otherwise valid module structure, the error points specifically to the missing item name.

Fix E0401: Cannot Find Type in This Scope

Sat, 25 Jul 2026 12:44:04 +0800

1. Symptoms

The Rust compiler produces error E0401 when it encounters a reference to a type that does not exist in the current scope. This error manifests with a clear diagnostic message that identifies both the problematic type and its location in your source code. The compiler provides line and column information to help you locate the exact position of the unresolvable type reference.

Typical error output from the Rust compiler looks like this:

Fix E0620: Unresolved Import in Rust

Fri, 17 Jul 2026 00:44:04 +0800

1. Symptoms

When the Rust compiler encounters error E0620, you will see output similar to the following in your terminal:

error[E0620]: unresolved import
 --> src/main.rs:3:5
  |
3 | use std::collections::HashMap;
  |     ^^^^^^^^^^^^^^^^^^^^^^^ unresolved import
  |
  = help: possible candidates are found in other crates, provide at least one additional import path like `use crate_name::collections::HashMap`

Alternatively, when referencing a module that doesn’t exist:

error[E0620]: unresolved import `foo::bar::baz`
 --> src/lib.rs:5:12
  |
5 | use foo::bar::baz::Quux;
  |            ^^^^^^^^^^^ unresolved import

The error manifests in several observable ways depending on the context. When you attempt to import a module that has not been declared in the nearest Cargo.toml or that doesn’t exist in the specified path, the compiler halts compilation and reports this specific error code. The error message explicitly states “unresolved import” and pinpoints the exact location in your source file where the problematic import statement resides.

Fix E0775: Attribute Must Be Placed Before `use`

Sat, 13 Jun 2026 15:08:04 +0800

1. Symptoms

When you attempt to compile Rust code with an attribute incorrectly placed after a use statement, the compiler immediately halts and produces error E0775. This error is unambiguous and typically appears during the parsing phase before any actual compilation begins.

You will see an error message similar to the following:

error[E0775]: attribute must be placed before `use`
 --> src/main.rs:6:1
  |
5 | use std::collections::HashMap;
6 | #[deprecated]
7 | use std::hash::Hash;
  | ^^^^^^^^^^^^^^^^^^^^ help: place attribute before the item: `#[deprecated] use std::hash::Hash;`

The compiler points directly to the problematic use statement and suggests the correct placement. The error occurs at the line where the attribute is incorrectly positioned, and the caret (^) aligns with the use keyword following the attribute.