rust/src/test/ui/span/unused-warning-point-at-identifier.rs

// run-pass

#![warn(unused)]

enum Enum { //~ WARN enum is never used
    A,
    B,
    C,
    D,
}

struct Struct { //~ WARN struct is never constructed
    a: usize,
    b: usize,
    c: usize,
    d: usize,
}

fn func() -> usize { //~ WARN function is never used
    3
}

fn
func_complete_span() //~ WARN function is never used
-> usize
{
    3
}

fn main() {}
Point at signature on unused lint 2017-09-25 14:01:55 -05:00			`// run-pass`

			`#![warn(unused)]`

Merge cfail and ui tests into ui tests 2017-11-20 06:13:27 -06:00			`enum Enum { //~ WARN enum is never used`
Point at signature on unused lint 2017-09-25 14:01:55 -05:00			`A,`
			`B,`
			`C,`
			`D,`
			`}`

dead-code lint: say "constructed" for structs This is a sequel to November 2017's #46103 / 1a9dc2e9. It had been reported (more than once—at least #19140, #44083, and #44565) that the "never used" language was confusing for enum variants that were "used" as match patterns, so the wording was changed to say never "constructed" specifically for enum variants. More recently, the same issue was raised for structs (#52325). It seems consistent to say "constructed" here, too, for the same reasons. We considered using more specific word "called" for unused functions and methods (while we declined to do this in #46103, the rationale given in the commit message doesn't actually make sense), but it turns out that Cargo's test suite expects the "never used" message, and maybe we don't care enough even to make a Cargo PR over such a petty and subjective wording change. This resolves #52325. 2018-07-21 19:55:34 -05:00			`struct Struct { //~ WARN struct is never constructed`
Point at signature on unused lint 2017-09-25 14:01:55 -05:00			`a: usize,`
			`b: usize,`
			`c: usize,`
			`d: usize,`
			`}`

Merge cfail and ui tests into ui tests 2017-11-20 06:13:27 -06:00			`fn func() -> usize { //~ WARN function is never used`
Point at signature on unused lint 2017-09-25 14:01:55 -05:00			`3`
			`}`

Use ident instead of def_span in dead-code pass According to @estebank, def_span scans forward on the line until it finds a {, and if it can't find one, fallse back to the span for the whole item. This was apparently written before the identifier span was explicitly tracked on each node. This means that if an unused function signature spans multiple lines, the entire function (potentially hundreds of lines) gets flagged as dead code. This could, for example, cause IDEs to add error squiggly's to the whole function. By using the span from the ident instead, we narrow the scope of this in most cases. In a wider sense, it's probably safe to use ident.span instead of def_span in most locations throughout the whole code base, but since this is my first contribution, I kept it small. Some interesting points that came up while I was working on this: - I reorganized the tests a bit to bring some of the dead code ones all into the same location - A few tests were for things unrelated to dead code (like the path-lookahead for parens), so I added #![allow(dead_code)] and cleaned up the stderr file to reduce noise in the future - The same fix doesn't apply to const and static declarations. I tried adding these cases to the match expression, but that created a much wider change to tests and error messages, so I left it off until I could get some code review to validate the approach. 2019-10-25 13:46:07 -05:00			`fn`
			`func_complete_span() //~ WARN function is never used`
Point at signature on unused lint 2017-09-25 14:01:55 -05:00			`-> usize`
			`{`
			`3`
			`}`

			`fn main() {}`