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-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0015.md | 33 |
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diff --git a/compiler/rustc_error_codes/src/error_codes/E0015.md b/compiler/rustc_error_codes/src/error_codes/E0015.md new file mode 100644 index 000000000..021a0219d --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0015.md @@ -0,0 +1,33 @@ +A constant item was initialized with something that is not a constant +expression. + +Erroneous code example: + +```compile_fail,E0015 +fn create_some() -> Option<u8> { + Some(1) +} + +const FOO: Option<u8> = create_some(); // error! +``` + +The only functions that can be called in static or constant expressions are +`const` functions, and struct/enum constructors. + +To fix this error, you can declare `create_some` as a constant function: + +``` +const fn create_some() -> Option<u8> { // declared as a const function + Some(1) +} + +const FOO: Option<u8> = create_some(); // ok! + +// These are also working: +struct Bar { + x: u8, +} + +const OTHER_FOO: Option<u8> = Some(1); +const BAR: Bar = Bar {x: 1}; +``` |