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Auto merge of #30102 - jFransham:feature/better-lifetime-errors, r=Manishearth

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Fixes #30086
This commit is contained in:
bors 2015-12-05 12:52:30 +00:00
commit d75f861518
2 changed files with 24 additions and 7 deletions
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25
src/librustc_typeck/astconv.rs
View File

@ -203,11 +203,15 @@ fn report_elision_failure(
{
let mut m = String::new();
let len = params.len();
let mut any_lifetimes = false;
for (i, info) in params.into_iter().enumerate() {
let ElisionFailureInfo {
name, lifetime_count: n, have_bound_regions
} = info;
any_lifetimes = any_lifetimes || (n > 0);
let help_name = if name.is_empty() {
format!("argument {}", i + 1)
} else {
@ -229,17 +233,26 @@ fn report_elision_failure(
m.push_str(", ");
}
}
if len == 1 {
fileline_help!(tcx.sess, default_span,
"this function's return type contains a borrowed value, but \
the signature does not say which {} it is borrowed from",
m);
} else if len == 0 {
if len == 0 {
fileline_help!(tcx.sess, default_span,
"this function's return type contains a borrowed value, but \
there is no value for it to be borrowed from");
fileline_help!(tcx.sess, default_span,
"consider giving it a 'static lifetime");
} else if !any_lifetimes {
fileline_help!(tcx.sess, default_span,
"this function's return type contains a borrowed value with \
an elided lifetime, but the lifetime cannot be derived from \
the arguments");
fileline_help!(tcx.sess, default_span,
"consider giving it an explicit bounded or 'static \
lifetime");
} else if len == 1 {
fileline_help!(tcx.sess, default_span,
"this function's return type contains a borrowed value, but \
the signature does not say which {} it is borrowed from",
m);
} else {
fileline_help!(tcx.sess, default_span,
"this function's return type contains a borrowed value, but \

6
src/test/compile-fail/issue-26638.rs
View File

@ -14,6 +14,10 @@ fn parse_type(iter: Box<Iterator<Item=&str>+'static>) -> &str { iter.next() }
fn parse_type_2(iter: fn(&u8)->&u8) -> &str { iter() }
//~^ ERROR missing lifetime specifier [E0106]
//~^^ HELP 0 elided free lifetimes
//~^^ HELP lifetime cannot be derived
fn parse_type_3() -> &str { unimplemented!() }
//~^ ERROR missing lifetime specifier [E0106]
//~^^ HELP no value for it to be borrowed from
fn main() {}