diff --git a/src/librustc_typeck/diagnostics.rs b/src/librustc_typeck/diagnostics.rs index 10bae6f63d0..0f6d5f249df 100644 --- a/src/librustc_typeck/diagnostics.rs +++ b/src/librustc_typeck/diagnostics.rs @@ -358,6 +358,97 @@ create an infinite recursion of dereferencing, in which case the only fix is to somehow break the recursion. "##, +E0057: r##" +When invoking closures or other implementations of the function traits `Fn`, +`FnMut` or `FnOnce` using call notation, the number of parameters passed to the +function must match its definition. + +An example using a closure: + +``` +let f = |x| x * 3; +let a = f(); // invalid, too few parameters +let b = f(4); // this works! +let c = f(2, 3); // invalid, too many parameters +``` + +A generic function must be treated similarly: + +``` +fn foo(f: F) { + f(); // this is valid, but f(3) would not work +} +``` +"##, + +E0059: r##" +The built-in function traits are generic over a tuple of the function arguments. +If one uses angle-bracket notation (`Fn<(T,), Output=U>`) instead of parentheses +(`Fn(T) -> U`) to denote the function trait, the type parameter should be a +tuple. Otherwise function call notation cannot be used and the trait will not be +implemented by closures. + +The most likely source of this error is using angle-bracket notation without +wrapping the function argument type into a tuple, for example: + +``` +fn foo>(f: F) -> F::Output { f(3) } +``` + +It can be fixed by adjusting the trait bound like this: + +``` +fn foo>(f: F) -> F::Output { f(3) } +``` + +Note that `(T,)` always denotes the type of a 1-tuple containing an element of +type `T`. The comma is necessary for syntactic disambiguation. +"##, + +E0060: r##" +External C functions are allowed to be variadic. However, a variadic function +takes a minimum number of arguments. For example, consider C's variadic `printf` +function: + +``` +extern crate libc; +use libc::{ c_char, c_int }; + +extern "C" { + fn printf(_: *const c_char, ...) -> c_int; +} +``` + +Using this declaration, it must be called with at least one argument, so +simply calling `printf()` is illegal. But the following uses are allowed: + +``` +unsafe { + use std::ffi::CString; + + printf(CString::new("test\n").unwrap().as_ptr()); + printf(CString::new("number = %d\n").unwrap().as_ptr(), 3); + printf(CString::new("%d, %d\n").unwrap().as_ptr(), 10, 5); +} +``` +"##, + +E0061: r##" +The number of arguments passed to a function must match the number of arguments +specified in the function signature. + +For example, a function like + +``` +fn f(a: u16, b: &str) {} +``` + +must always be called with exactly two arguments, e.g. `f(2, "test")`. + +Note, that Rust does not have a notion of optional function arguments or +variadic functions (except for its C-FFI). +"##, + E0062: r##" This error indicates that during an attempt to build a struct or struct-like enum variant, one of the fields was specified more than once. Each field should @@ -1210,10 +1301,6 @@ register_diagnostics! { E0036, // incorrect number of type parameters given for this method E0044, // foreign items may not have type parameters E0045, // variadic function must have C calling convention - E0057, // method has an incompatible type for trait - E0059, - E0060, - E0061, E0068, E0071, E0074,