Diagnostics

While most errors and warnings provided by rust-analyzer come from the cargo check integration, there’s a growing number of diagnostics implemented using rust-analyzer’s own analysis. Some of these diagnostics don’t respect #[allow] or \#[deny] attributes yet, but can be turned off using the rust-analyzer.diagnostics.enable, rust-analyzer.diagnostics.experimental.enable or rust-analyzer.diagnostics.disabled settings.

Clippy

To run cargo clippy instead of cargo check, you can set "rust-analyzer.check.command": "clippy".

break-outside-of-loop

Source: break_outside_of_loop.rs

This diagnostic is triggered if the break keyword is used outside of a loop.

expected-function

Source: expected_function.rs

This diagnostic is triggered if a call is made on something that is not callable.

inactive-code

Source: inactive_code.rs

This diagnostic is shown for code with inactive #[cfg] attributes.

incoherent-impl

Source: incoherent_impl.rs

This diagnostic is triggered if the targe type of an impl is from a foreign crate.

incorrect-ident-case

Source: incorrect_case.rs

This diagnostic is triggered if an item name doesn't follow Rust naming convention.

invalid-derive-target

Source: invalid_derive_target.rs

This diagnostic is shown when the derive attribute is used on an item other than a struct, enum or union.

macro-error

Source: macro_error.rs

This diagnostic is shown for macro expansion errors.

macro-error

Source: macro_error.rs

This diagnostic is shown for macro expansion errors.

malformed-derive

Source: malformed_derive.rs

This diagnostic is shown when the derive attribute has invalid input.

mismatched-arg-count

Source: mismatched_arg_count.rs

This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.

mismatched-tuple-struct-pat-arg-count

Source: mismatched_arg_count.rs

This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.

missing-fields

Source: missing_fields.rs

This diagnostic is triggered if record lacks some fields that exist in the corresponding structure.

Example:

struct A { a: u8, b: u8 }

let a = A { a: 10 };

missing-match-arm

Source: missing_match_arms.rs

This diagnostic is triggered if match block is missing one or more match arms.

missing-unsafe

Source: missing_unsafe.rs

This diagnostic is triggered if an operation marked as unsafe is used outside of an unsafe function or block.

moved-out-of-ref

Source: moved_out_of_ref.rs

This diagnostic is triggered on moving non copy things out of references.

need-mut

Source: mutability_errors.rs

This diagnostic is triggered on mutating an immutable variable.

no-such-field

Source: no_such_field.rs

This diagnostic is triggered if created structure does not have field provided in record.

private-assoc-item

Source: private_assoc_item.rs

This diagnostic is triggered if the referenced associated item is not visible from the current module.

private-field

Source: private_field.rs

This diagnostic is triggered if the accessed field is not visible from the current module.

replace-filter-map-next-with-find-map

Source: replace_filter_map_next_with_find_map.rs

This diagnostic is triggered when .filter_map(..).next() is used, rather than the more concise .find_map(..).

type-mismatch

Source: type_mismatch.rs

This diagnostic is triggered when the type of an expression or pattern does not match the expected type.

typed-hole

Source: typed_hole.rs

This diagnostic is triggered when an underscore expression is used in an invalid position.

undeclared-label

Source: undeclared_label.rs

unimplemented-builtin-macro

Source: unimplemented_builtin_macro.rs

This diagnostic is shown for builtin macros which are not yet implemented by rust-analyzer

unlinked-file

Source: unlinked_file.rs

This diagnostic is shown for files that are not included in any crate, or files that are part of crates rust-analyzer failed to discover. The file will not have IDE features available.

unnecessary-braces

Source: useless_braces.rs

Diagnostic for unnecessary braces in use items.

unreachable-label

Source: unreachable_label.rs

unresolved-extern-crate

Source: unresolved_extern_crate.rs

This diagnostic is triggered if rust-analyzer is unable to discover referred extern crate.

unresolved-field

Source: unresolved_field.rs

This diagnostic is triggered if a field does not exist on a given type.

unresolved-import

Source: unresolved_import.rs

This diagnostic is triggered if rust-analyzer is unable to resolve a path in a use declaration.

unresolved-macro-call

Source: unresolved_macro_call.rs

This diagnostic is triggered if rust-analyzer is unable to resolve the path to a macro in a macro invocation.

unresolved-method

Source: unresolved_method.rs

This diagnostic is triggered if a method does not exist on a given type.

unresolved-module

Source: unresolved_module.rs

This diagnostic is triggered if rust-analyzer is unable to discover referred module.

unresolved-proc-macro

Source: unresolved_proc_macro.rs

This diagnostic is shown when a procedural macro can not be found. This usually means that procedural macro support is simply disabled (and hence is only a weak hint instead of an error), but can also indicate project setup problems.

If you are seeing a lot of "proc macro not expanded" warnings, you can add this option to the rust-analyzer.diagnostics.disabled list to prevent them from showing. Alternatively you can enable support for procedural macros (see rust-analyzer.procMacro.attributes.enable).

unused-mut

Source: mutability_errors.rs

This diagnostic is triggered when a mutable variable isn't actually mutated.

unused-variables

Source: unused_variables.rs

This diagnostic is triggered when a local variable is not used.