1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 #![allow(non_snake_case)]
13 // Error messages for EXXXX errors. Each message should start and end with a
14 // new line, and be wrapped to 80 characters. In vim you can `:set tw=80` and
15 // use `gq` to wrap paragraphs. Use `:set tw=0` to disable.
16 register_long_diagnostics! {
19 Type parameter defaults can only use parameters that occur before them.
20 Erroneous code example:
23 struct Foo<T=U, U=()> {
27 // error: type parameters with a default cannot use forward declared
31 Since type parameters are evaluated in-order, you may be able to fix this issue
35 struct Foo<U=(), T=U> {
41 Please also verify that this wasn't because of a name-clash and rename the type
46 #### Note: this error code is no longer emitted by the compiler.
48 Imports (`use` statements) are not allowed after non-item statements, such as
49 variable declarations and expression statements.
51 Here is an example that demonstrates the error:
55 // Variable declaration before import
62 The solution is to declare the imports at the top of the block, function, or
65 Here is the previous example again, with the correct order:
75 See the Declaration Statements section of the reference for more information
76 about what constitutes an Item declaration and what does not:
78 https://doc.rust-lang.org/reference.html#statements
82 #### Note: this error code is no longer emitted by the compiler.
84 Two items of the same name cannot be imported without rebinding one of the
85 items under a new local name.
87 An example of this error:
91 use bar::*; // error, do `use foo::baz as quux` instead on the previous line
106 Two items of the same name cannot be imported without rebinding one of the
107 items under a new local name.
109 Erroneous code example:
111 ```compile_fail,E0252
113 use bar::baz; // error, do `use bar::baz as quux` instead
126 You can use aliases in order to fix this error. Example:
129 use foo::baz as foo_baz;
143 Or you can reference the item with its parent:
149 let x = foo::baz; // ok!
163 Attempt was made to import an unimportable value. This can happen when trying
164 to import a method from a trait.
166 Erroneous code example:
168 ```compile_fail,E0253
175 use foo::MyTrait::do_something;
176 // error: `do_something` is not directly importable
181 It's invalid to directly import methods belonging to a trait or concrete type.
185 Attempt was made to import an item whereas an extern crate with this name has
186 already been imported.
188 Erroneous code example:
190 ```compile_fail,E0254
199 use foo::core; // error: an extern crate named `core` has already
200 // been imported in this module
205 To fix issue issue, you have to rename at least one of the two imports.
209 extern crate core as libcore; // ok!
224 You can't import a value whose name is the same as another value defined in the
227 Erroneous code example:
229 ```compile_fail,E0255
230 use bar::foo; // error: an item named `foo` is already in scope
241 You can use aliases in order to fix this error. Example:
244 use bar::foo as bar_foo; // ok!
255 Or you can reference the item with its parent:
265 bar::foo(); // we get the item by referring to its parent
271 #### Note: this error code is no longer emitted by the compiler.
273 You can't import a type or module when the name of the item being imported is
274 the same as another type or submodule defined in the module.
276 An example of this error:
279 use foo::Bar; // error
292 The name chosen for an external crate conflicts with another external crate
293 that has been imported into the current module.
295 Erroneous code example:
297 ```compile_fail,E0259
300 extern crate libc as core;
305 The solution is to choose a different name that doesn't conflict with any
306 external crate imported into the current module.
313 extern crate libc as other_name;
320 The name for an item declaration conflicts with an external crate's name.
322 Erroneous code example:
324 ```compile_fail,E0260
332 There are two possible solutions:
334 Solution #1: Rename the item.
342 Solution #2: Import the crate with a different name.
345 extern crate core as xyz;
350 See the Declaration Statements section of the reference for more information
351 about what constitutes an Item declaration and what does not:
353 https://doc.rust-lang.org/reference.html#statements
357 Private items cannot be publicly re-exported. This error indicates that you
358 attempted to `pub use` a type or value that was not itself public.
360 Erroneous code example:
372 The solution to this problem is to ensure that the items that you are
373 re-exporting are themselves marked with `pub`:
377 pub const X: u32 = 1;
385 See the 'Use Declarations' section of the reference for more information on
388 https://doc.rust-lang.org/reference.html#use-declarations
392 Private modules cannot be publicly re-exported. This error indicates that you
393 attempted to `pub use` a module that was not itself public.
395 Erroneous code example:
397 ```compile_fail,E0365
399 pub const X: u32 = 1;
407 The solution to this problem is to ensure that the module that you are
408 re-exporting is itself marked with `pub`:
412 pub const X: u32 = 1;
420 See the 'Use Declarations' section of the reference for more information
423 https://doc.rust-lang.org/reference.html#use-declarations
427 Inner items do not inherit type parameters from the functions they are embedded
430 Erroneous code example:
432 ```compile_fail,E0401
434 fn bar(y: T) { // T is defined in the "outer" function
443 ```compile_fail,E0401
445 type MaybeT = Option<T>;
452 ```compile_fail,E0401
461 Items inside functions are basically just like top-level items, except
462 that they can only be used from the function they are in.
464 There are a couple of solutions for this.
466 If the item is a function, you may use a closure:
470 let bar = |y: T| { // explicit type annotation may not be necessary
477 For a generic item, you can copy over the parameters:
490 type MaybeT<T> = Option<T>;
494 Be sure to copy over any bounds as well:
497 fn foo<T: Copy>(x: T) {
498 fn bar<T: Copy>(y: T) {
506 fn foo<T: Copy>(x: T) {
507 struct Foo<T: Copy> {
513 This may require additional type hints in the function body.
515 In case the item is a function inside an `impl`, defining a private helper
516 function might be easier:
521 pub fn foo(&self, x: T) {
525 fn bar(&self, y: T) {
531 For default impls in traits, the private helper solution won't work, however
532 closures or copying the parameters should still work.
536 Some type parameters have the same name.
538 Erroneous code example:
540 ```compile_fail,E0403
541 fn foo<T, T>(s: T, u: T) {} // error: the name `T` is already used for a type
542 // parameter in this type parameter list
545 Please verify that none of the type parameterss are misspelled, and rename any
546 clashing parameters. Example:
549 fn foo<T, Y>(s: T, u: Y) {} // ok!
554 You tried to implement something which was not a trait on an object.
556 Erroneous code example:
558 ```compile_fail,E0404
562 impl Foo for Bar {} // error: `Foo` is not a trait
565 Please verify that you didn't misspell the trait's name or otherwise use the
566 wrong identifier. Example:
574 impl Foo for Bar { // ok!
575 // functions implementation
581 The code refers to a trait that is not in scope.
583 Erroneous code example:
585 ```compile_fail,E0405
588 impl SomeTrait for Foo {} // error: trait `SomeTrait` is not in scope
591 Please verify that the name of the trait wasn't misspelled and ensure that it
592 was imported. Example:
595 # #[cfg(for_demonstration_only)]
597 use some_file::SomeTrait;
606 impl SomeTrait for Foo { // ok!
607 // implements functions
613 A definition of a method not in the implemented trait was given in a trait
616 Erroneous code example:
618 ```compile_fail,E0407
627 fn b() {} // error: method `b` is not a member of trait `Foo`
631 Please verify you didn't misspell the method name and you used the correct
632 trait. First example:
668 An "or" pattern was used where the variable bindings are not consistently bound
671 Erroneous code example:
673 ```compile_fail,E0408
675 Some(y) | None => { /* use y */ } // error: variable `y` from pattern #1 is
676 // not bound in pattern #2
681 Here, `y` is bound to the contents of the `Some` and can be used within the
682 block corresponding to the match arm. However, in case `x` is `None`, we have
683 not specified what `y` is, and the block will use a nonexistent variable.
685 To fix this error, either split into multiple match arms:
690 Some(y) => { /* use y */ }
691 None => { /* ... */ }
695 or, bind the variable to a field of the same type in all sub-patterns of the
701 (0, y) | (y, 0) => { /* use y */}
706 In this example, if `x` matches the pattern `(0, _)`, the second field is set
707 to `y`. If it matches `(_, 0)`, the first field is set to `y`; so in all
708 cases `y` is set to some value.
712 An "or" pattern was used where the variable bindings are not consistently bound
715 Erroneous code example:
717 ```compile_fail,E0409
720 (0, ref y) | (y, 0) => { /* use y */} // error: variable `y` is bound with
721 // different mode in pattern #2
722 // than in pattern #1
727 Here, `y` is bound by-value in one case and by-reference in the other.
729 To fix this error, just use the same mode in both cases.
730 Generally using `ref` or `ref mut` where not already used will fix this:
735 (0, ref y) | (ref y, 0) => { /* use y */}
740 Alternatively, split the pattern:
745 (y, 0) => { /* use y */ }
746 (0, ref y) => { /* use y */}
753 The `Self` keyword was used outside an impl or a trait.
755 Erroneous code example:
757 ```compile_fail,E0411
758 <Self>::foo; // error: use of `Self` outside of an impl or trait
761 The `Self` keyword represents the current type, which explains why it can only
762 be used inside an impl or a trait. It gives access to the associated items of a
771 fn bar() -> Self::Bar; // like this
775 However, be careful when two types have a common associated type:
786 trait Baz : Foo + Foo2 {
787 fn bar() -> Self::Bar;
788 // error: ambiguous associated type `Bar` in bounds of `Self`
792 This problem can be solved by specifying from which trait we want to use the
804 trait Baz : Foo + Foo2 {
805 fn bar() -> <Self as Foo>::Bar; // ok!
811 The type name used is not in scope.
813 Erroneous code examples:
815 ```compile_fail,E0412
816 impl Something {} // error: type name `Something` is not in scope
821 fn bar(N); // error: type name `N` is not in scope
826 fn foo(x: T) {} // type name `T` is not in scope
829 To fix this error, please verify you didn't misspell the type name, you did
830 declare it or imported it into the scope. Examples:
835 impl Something {} // ok!
842 fn bar(_: Self::N); // ok!
847 fn foo<T>(x: T) {} // ok!
850 Another case that causes this error is when a type is imported into a parent
851 module. To fix this, you can follow the suggestion and use File directly or
852 `use super::File;` which will import the types from the parent namespace. An
853 example that causes this error is below:
855 ```compile_fail,E0412
859 fn some_function(f: File) {}
870 // use std::fs::File;
873 # fn main() {} // don't insert it for us; that'll break imports
878 More than one function parameter have the same name.
880 Erroneous code example:
882 ```compile_fail,E0415
883 fn foo(f: i32, f: i32) {} // error: identifier `f` is bound more than
884 // once in this parameter list
887 Please verify you didn't misspell parameters' name. Example:
890 fn foo(f: i32, g: i32) {} // ok!
895 An identifier is bound more than once in a pattern.
897 Erroneous code example:
899 ```compile_fail,E0416
901 (x, x) => {} // error: identifier `x` is bound more than once in the
906 Please verify you didn't misspell identifiers' name. Example:
914 Or maybe did you mean to unify? Consider using a guard:
917 # let (A, B, C) = (1, 2, 3);
919 (x, x2, see) if x == x2 => { /* A and B are equal, do one thing */ }
920 (y, z, see) => { /* A and B unequal; do another thing */ }
926 You are trying to use an identifier that is either undefined or not a struct.
927 Erroneous code example:
929 ```compile_fail,E0422
931 let x = Foo { x: 1, y: 2 };
935 In this case, `Foo` is undefined, so it inherently isn't anything, and
936 definitely not a struct.
941 let x = foo { x: 1, y: 2 };
945 In this case, `foo` is defined, but is not a struct, so Rust can't use it as
950 A `struct` variant name was used like a function name.
952 Erroneous code example:
954 ```compile_fail,E0423
955 struct Foo { a: bool };
958 // error: `Foo` is a struct variant name, but this expression uses
959 // it like a function name
962 Please verify you didn't misspell the name of what you actually wanted to use
966 fn Foo() -> u32 { 0 }
968 let f = Foo(); // ok!
973 The `self` keyword was used in a static method.
975 Erroneous code example:
977 ```compile_fail,E0424
984 self.bar(); // error: `self` is not available in a static method.
989 Please check if the method's argument list should have contained `self`,
990 `&self`, or `&mut self` (in case you didn't want to create a static
991 method), and add it if so. Example:
1007 An unresolved name was used.
1009 Erroneous code examples:
1011 ```compile_fail,E0425
1012 something_that_doesnt_exist::foo;
1013 // error: unresolved name `something_that_doesnt_exist::foo`
1019 Self; // error: unresolved name `Self`
1025 let x = unknown_variable; // error: unresolved name `unknown_variable`
1028 Please verify that the name wasn't misspelled and ensure that the
1029 identifier being referred to is valid for the given situation. Example:
1032 enum something_that_does_exist {
1040 mod something_that_does_exist {
1041 pub static foo : i32 = 0i32;
1044 something_that_does_exist::foo; // ok!
1050 let unknown_variable = 12u32;
1051 let x = unknown_variable; // ok!
1054 If the item is not defined in the current module, it must be imported using a
1055 `use` statement, like so:
1058 # mod foo { pub fn bar() {} }
1065 If the item you are importing is not defined in some super-module of the
1066 current module, then it must also be declared as public (e.g., `pub fn`).
1070 An undeclared label was used.
1072 Erroneous code example:
1074 ```compile_fail,E0426
1076 break 'a; // error: use of undeclared label `'a`
1080 Please verify you spelt or declare the label correctly. Example:
1090 A type or module has been defined more than once.
1092 Erroneous code example:
1094 ```compile_fail,E0428
1096 struct Bar; // error: duplicate definition of value `Bar`
1099 Please verify you didn't misspell the type/module's name or remove/rename the
1100 duplicated one. Example:
1109 The `self` keyword cannot appear alone as the last segment in a `use`
1112 Erroneous code example:
1114 ```compile_fail,E0429
1115 use std::fmt::self; // error: `self` imports are only allowed within a { } list
1118 To use a namespace itself in addition to some of its members, `self` may appear
1119 as part of a brace-enclosed list of imports:
1122 use std::fmt::{self, Debug};
1125 If you only want to import the namespace, do so directly:
1133 The `self` import appears more than once in the list.
1135 Erroneous code example:
1137 ```compile_fail,E0430
1138 use something::{self, self}; // error: `self` import can only appear once in
1142 Please verify you didn't misspell the import name or remove the duplicated
1143 `self` import. Example:
1148 use something::{self}; // ok!
1154 An invalid `self` import was made.
1156 Erroneous code example:
1158 ```compile_fail,E0431
1159 use {self}; // error: `self` import can only appear in an import list with a
1163 You cannot import the current module into itself, please remove this import
1164 or verify you didn't misspell it.
1168 An import was unresolved.
1170 Erroneous code example:
1172 ```compile_fail,E0432
1173 use something::Foo; // error: unresolved import `something::Foo`.
1176 Paths in `use` statements are relative to the crate root. To import items
1177 relative to the current and parent modules, use the `self::` and `super::`
1178 prefixes, respectively. Also verify that you didn't misspell the import
1179 name and that the import exists in the module from where you tried to
1183 use self::something::Foo; // ok!
1191 Or, if you tried to use a module from an external crate, you may have missed
1192 the `extern crate` declaration (which is usually placed in the crate root):
1195 extern crate core; // Required to use the `core` crate
1203 An undeclared type or module was used.
1205 Erroneous code example:
1207 ```compile_fail,E0433
1208 let map = HashMap::new();
1209 // error: failed to resolve. Use of undeclared type or module `HashMap`
1212 Please verify you didn't misspell the type/module's name or that you didn't
1213 forgot to import it:
1217 use std::collections::HashMap; // HashMap has been imported.
1218 let map: HashMap<u32, u32> = HashMap::new(); // So it can be used!
1223 This error indicates that a variable usage inside an inner function is invalid
1224 because the variable comes from a dynamic environment. Inner functions do not
1225 have access to their containing environment.
1227 Erroneous code example:
1229 ```compile_fail,E0434
1233 y // error: can't capture dynamic environment in a fn item; use the
1234 // || { ... } closure form instead.
1239 Functions do not capture local variables. To fix this error, you can replace the
1240 function with a closure:
1251 or replace the captured variable with a constant or a static item:
1255 static mut X: u32 = 4;
1268 A non-constant value was used in a constant expression.
1270 Erroneous code example:
1272 ```compile_fail,E0435
1274 let a: [u8; foo]; // error: attempt to use a non-constant value in a constant
1277 To fix this error, please replace the value with a constant. Example:
1280 let a: [u8; 42]; // ok!
1286 const FOO: usize = 42;
1287 let a: [u8; FOO]; // ok!
1292 Trait implementations can only implement associated types that are members of
1293 the trait in question. This error indicates that you attempted to implement
1294 an associated type whose name does not match the name of any associated type
1297 Erroneous code example:
1299 ```compile_fail,E0437
1307 The solution to this problem is to remove the extraneous associated type:
1317 Trait implementations can only implement associated constants that are
1318 members of the trait in question. This error indicates that you
1319 attempted to implement an associated constant whose name does not
1320 match the name of any associated constant in the trait.
1322 Erroneous code example:
1324 ```compile_fail,E0438
1328 const BAR: bool = true;
1332 The solution to this problem is to remove the extraneous associated constant:
1342 Macro import declarations were malformed.
1344 Erroneous code examples:
1346 ```compile_fail,E0466
1347 #[macro_use(a_macro(another_macro))] // error: invalid import declaration
1348 extern crate core as some_crate;
1350 #[macro_use(i_want = "some_macros")] // error: invalid import declaration
1351 extern crate core as another_crate;
1354 This is a syntax error at the level of attribute declarations. The proper
1355 syntax for macro imports is the following:
1357 ```ignore (cannot-doctest-multicrate-project)
1360 macro_rules! get_tacos {
1365 macro_rules! get_pimientos {
1370 #[macro_use(get_tacos, get_pimientos)] // It imports `get_tacos` and
1371 extern crate some_crate; // `get_pimientos` macros from some_crate
1374 If you would like to import all exported macros, write `macro_use` with no
1379 Macro re-export declarations were empty or malformed.
1381 Erroneous code examples:
1383 ```compile_fail,E0467
1384 #[macro_reexport] // error: no macros listed for export
1385 extern crate core as macros_for_good;
1387 #[macro_reexport(fun_macro = "foo")] // error: not a macro identifier
1388 extern crate core as other_macros_for_good;
1391 This is a syntax error at the level of attribute declarations.
1393 Currently, `macro_reexport` requires at least one macro name to be listed.
1394 Unlike `macro_use`, listing no names does not re-export all macros from the
1397 Decide which macros you would like to export and list them properly.
1399 These are proper re-export declarations:
1401 ```ignore (cannot-doctest-multicrate-project)
1402 #[macro_reexport(some_macro, another_macro)]
1403 extern crate macros_for_good;
1408 A non-root module attempts to import macros from another crate.
1410 Example of erroneous code:
1412 ```compile_fail,E0468
1414 #[macro_use(debug_assert)] // error: must be at crate root to import
1415 extern crate core; // macros from another crate
1416 fn run_macro() { debug_assert!(true); }
1420 Only `extern crate` imports at the crate root level are allowed to import
1423 Either move the macro import to crate root or do without the foreign macros.
1427 #[macro_use(debug_assert)]
1431 fn run_macro() { debug_assert!(true); }
1438 A macro listed for import was not found.
1440 Erroneous code example:
1442 ```compile_fail,E0469
1443 #[macro_use(drink, be_merry)] // error: imported macro not found
1451 Either the listed macro is not contained in the imported crate, or it is not
1452 exported from the given crate.
1454 This could be caused by a typo. Did you misspell the macro's name?
1456 Double-check the names of the macros listed for import, and that the crate
1457 in question exports them.
1459 A working version would be:
1461 ```ignore (cannot-doctest-multicrate-project)
1462 // In some_crate crate:
1469 macro_rules! drink {
1474 #[macro_use(eat, drink)]
1475 extern crate some_crate; //ok!
1480 A macro listed for re-export was not found.
1482 Erroneous code example:
1484 ```compile_fail,E0470
1485 #[macro_reexport(drink, be_merry)]
1493 Either the listed macro is not contained in the imported crate, or it is not
1494 exported from the given crate.
1496 This could be caused by a typo. Did you misspell the macro's name?
1498 Double-check the names of the macros listed for re-export, and that the crate
1499 in question exports them.
1503 ```ignore (cannot-doctest-multicrate-project)
1504 // In some_crate crate:
1511 macro_rules! drink {
1516 #[macro_reexport(eat, drink)]
1517 extern crate some_crate;
1522 A binding shadowed something it shouldn't.
1524 Erroneous code example:
1526 ```compile_fail,E0530
1527 static TEST: i32 = 0;
1529 let r: (i32, i32) = (0, 0);
1531 TEST => {} // error: match bindings cannot shadow statics
1535 To fix this error, just change the binding's name in order to avoid shadowing
1536 one of the following:
1539 * struct/enum variant
1547 static TEST: i32 = 0;
1549 let r: (i32, i32) = (0, 0);
1551 something => {} // ok!
1557 Pattern arm did not match expected kind.
1559 Erroneous code example:
1561 ```compile_fail,E0532
1567 fn print_on_failure(state: &State) {
1569 // error: expected unit struct/variant or constant, found tuple
1570 // variant `State::Failed`
1571 State::Failed => println!("Failed"),
1577 To fix this error, ensure the match arm kind is the same as the expression
1588 fn print_on_failure(state: &State) {
1590 State::Failed(ref msg) => println!("Failed with {}", msg),
1598 A private item was used outside its scope.
1600 Erroneous code example:
1602 ```compile_fail,E0603
1604 const PRIVATE: u32 = 0x_a_bad_1dea_u32; // This const is private, so we
1605 // can't use it outside of the
1606 // `SomeModule` module.
1609 println!("const value: {}", SomeModule::PRIVATE); // error: constant `CONSTANT`
1613 In order to fix this error, you need to make the item public by using the `pub`
1618 pub const PRIVATE: u32 = 0x_a_bad_1dea_u32; // We set it public by using the
1622 println!("const value: {}", SomeModule::PRIVATE); // ok!
1627 An item usage is ambiguous.
1629 Erroneous code example:
1631 ```compile_fail,E0659
1646 collider::foo(); // ERROR: `foo` is ambiguous
1650 This error generally appears when two items with the same name are imported into
1651 a module. Here, the `foo` functions are imported and reexported from the
1652 `collider` module and therefore, when we're using `collider::foo()`, both
1655 To solve this error, the best solution is generally to keep the path before the
1656 item when using it. Example:
1673 collider::moon::foo(); // ok!
1674 collider::earth::foo(); // ok!
1681 register_diagnostics! {
1682 // E0153, unused error code
1683 // E0157, unused error code
1686 // E0402, // cannot use an outer type parameter in this context
1687 // E0406, merged into 420
1688 // E0410, merged into 408
1689 // E0413, merged into 530
1690 // E0414, merged into 530
1691 // E0417, merged into 532
1692 // E0418, merged into 532
1693 // E0419, merged into 531
1694 // E0420, merged into 532
1695 // E0421, merged into 531
1696 E0531, // unresolved pattern path kind `name`
1697 // E0427, merged into 530