diff options
| -rw-r--r-- | src/librustc/diagnostics.rs | 69 |
1 files changed, 1 insertions, 68 deletions
diff --git a/src/librustc/diagnostics.rs b/src/librustc/diagnostics.rs index 76fba1583f3..26f56ffacae 100644 --- a/src/librustc/diagnostics.rs +++ b/src/librustc/diagnostics.rs @@ -1351,74 +1351,6 @@ struct Foo<T: 'static> { ``` "##, -E0312: r##" -A lifetime of reference outlives lifetime of borrowed content. - -Erroneous code example: - -```compile_fail,E0312 -fn make_child<'tree, 'human>( - x: &'human i32, - y: &'tree i32 -) -> &'human i32 { - if x > y - { x } - else - { y } - // error: lifetime of reference outlives lifetime of borrowed content -} -``` - -The function declares that it returns a reference with the `'human` -lifetime, but it may return data with the `'tree` lifetime. As neither -lifetime is declared longer than the other, this results in an -error. Sometimes, this error is because the function *body* is -incorrect -- that is, maybe you did not *mean* to return data from -`y`. In that case, you should fix the function body. - -Often, however, the body is correct. In that case, the function -signature needs to be altered to match the body, so that the caller -understands that data from either `x` or `y` may be returned. The -simplest way to do this is to give both function parameters the *same* -named lifetime: - -``` -fn make_child<'human>( - x: &'human i32, - y: &'human i32 -) -> &'human i32 { - if x > y - { x } - else - { y } // ok! -} -``` - -However, in some cases, you may prefer to explicitly declare that one lifetime -outlives another using a `where` clause: - -``` -fn make_child<'tree, 'human>( - x: &'human i32, - y: &'tree i32 -) -> &'human i32 -where - 'tree: 'human -{ - if x > y - { x } - else - { y } // ok! -} -``` - -Here, the where clause `'tree: 'human` can be read as "the lifetime -'tree outlives the lifetime 'human" -- meaning, references with the -`'tree` lifetime live *at least as long as* references with the -`'human` lifetime. Therefore, it is safe to return data with lifetime -`'tree` when data with the lifetime `'human` is needed. -"##, - E0317: r##" This error occurs when an `if` expression without an `else` block is used in a context where a type other than `()` is expected, for example a `let` @@ -2028,6 +1960,7 @@ register_diagnostics! { // E0304, // expected signed integer constant // E0305, // expected constant E0311, // thing may not live long enough + E0312, // lifetime of reference outlives lifetime of borrowed content E0313, // lifetime of borrowed pointer outlives lifetime of captured variable E0314, // closure outlives stack frame E0315, // cannot invoke closure outside of its lifetime |