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Description
Clippy told me to file a bug report after it reports three occurrences of "unnecessary_to_owned" in a single method that it can't fix.
hdt$ cargo clippy --fix
Checking hdt v0.0.8 (/home/konrad/tmp/hdt)
warning: failed to automatically apply fixes suggested by rustc to crate `hdt`
after fixes were automatically applied the compiler reported errors within these files:
* src/hdt_graph.rs
This likely indicates a bug in either rustc or cargo itself [...]
The following errors were reported:
error[E0521]: borrowed data escapes outside of function
--> src/hdt_graph.rs:86:14
|
51 | fn auto_term<T: Data>(s: &str) -> Result<Term<T>, TermError> {
| - - let's call the lifetime of this reference `'1`
| |
| `s` is a reference that is only valid in the function body
...
86 | _ => Term::<T>::new_iri(s),
| ^^^^^^^^^^^^^^^^^^^^^
| |
| `s` escapes the function body here
| argument requires that `'1` must outlive `'static`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0521`.
Original diagnostics will follow.
warning: unnecessary use of `to_owned`
--> src/hdt_graph.rs:69:25
|
69 | rest[tag_index + 1..].to_owned(),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `&rest[tag_index + 1..]`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_to_owned
= note: `#[warn(clippy::unnecessary_to_owned)]` on by default
warning: unnecessary use of `to_owned`
--> src/hdt_graph.rs:85:43
|
85 | Some('_') => Term::<T>::new_bnode(s[2..].to_owned()),
| ^^^^^^^^^^^^^^^^^ help: use: `&s[2..]`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_to_owned
warning: unnecessary use of `to_owned`
--> src/hdt_graph.rs:86:33
|
86 | _ => Term::<T>::new_iri(s.to_owned()),
| ^^^^^^^^^^^^ help: use: `s`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_to_owned
warning: `hdt` (lib) generated 3 warnings (run `cargo clippy --fix --lib -p hdt` to apply 3 suggestions)
warning: `hdt` (lib test) generated 3 warnings (3 duplicates)
Finished dev [unoptimized + debuginfo] target(s) in 0.88s
The method in question is:
pub trait Data:
AsRef<str> + Clone + Eq + From<std::boxed::Box<str>> + From<String> + From<&'static str> + Hash
{
}
impl<T> Data for T where
T: AsRef<str> + Clone + Eq + From<std::boxed::Box<str>> + From<String> + From<&'static str> + Hash
{
}
impl<T: Data> HdtGraph<T> {
/// Wrapper around Hdt.
pub const fn new(hdt: Hdt) -> Self {
HdtGraph { hdt, phantom: PhantomData {} }
}
/// Size in bytes on the heap.
pub fn size_in_bytes(&self) -> usize {
self.hdt.size_in_bytes()
}
}
const XSD_STRING: &str = "http://www.w3.org/2001/XMLSchema#string";
/// Create the correct Sophia term for a given resource string.
/// Slow, use the appropriate method if you know which type (Literal, URI, or blank node) the string has.
fn auto_term<T: Data>(s: &str) -> Result<Term<T>, TermError> {
match s.chars().next() {
None => Err(TermError::InvalidIri(String::new())),
Some('"') => match s.rfind('"') {
None => Err(TermError::UnsupportedDatatype(s.to_owned())),
Some(index) => {
let lex = s[1..index].to_owned();
let rest = &s[index + 1..];
// literal with no language tag and no datatype
if rest.is_empty() {
//let dt_string: sophia::term::iri::Iri<&str> = Iri::<&str>::new_unchecked(XSD_STRING);
let dt_string = Iri::<&str>::new_unchecked(XSD_STRING);
return Ok(Term::<T>::from(Literal::new_dt(lex, dt_string)));
}
// either language tag or datatype
if let Some(tag_index) = rest.find('@') {
return Ok(Term::<T>::from(Literal::new_lang_unchecked(
lex,
rest[tag_index + 1..].to_owned(),
)));
}
// datatype
let mut dt_split = rest.split("^^");
dt_split.next(); // empty
match dt_split.next() {
Some(dt) => {
let unquoted = dt[1..dt.len() - 1].to_owned().into_boxed_str();
let dt = Iri::<Box<str>>::new_unchecked(unquoted);
Ok(Term::<T>::from(Literal::new_dt(lex, dt)))
}
None => Err(TermError::UnsupportedDatatype(s.to_owned())),
}
}
},
Some('_') => Term::<T>::new_bnode(s[2..].to_owned()),
_ => Term::<T>::new_iri(s.to_owned()),
}
}rustc --version --verbose:
rustc 1.68.0-nightly (77429957a 2023-01-01)
binary: rustc
commit-hash: 77429957a0e9c90a26c89def061ffdd4bae5ccb9
commit-date: 2023-01-01
host: x86_64-unknown-linux-gnu
release: 1.68.0-nightly
LLVM version: 15.0.6
The problem can be replicated in KonradHoeffner/hdt@197b728.