Rollup merge of #151530 - reddevilmidzy:e0106, r=fee1-dead
Fix invalid `mut T` suggestion for `&mut T` in missing lifetime error close: rust-lang/rust#150077 When suggesting to return an owned value instead of a borrowed one, the diagnostic was only removing `&` instead of `&mut `, resulting in invalid syntax like `mut T`. This PR fixes the span calculation to properly cover the entire `&mut ` prefix.
This commit is contained in:
Stuart Cook
GitHub
commit
a544b5df98
3 changed files with 231 additions and 13 deletions
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@ -4060,25 +4060,32 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
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"instead, you are more likely to want"
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};
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let mut owned_sugg = lt.kind == MissingLifetimeKind::Ampersand;
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let mut sugg_is_str_to_string = false;
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let mut sugg = vec![(lt.span, String::new())];
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if let Some((kind, _span)) = self.diag_metadata.current_function
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&& let FnKind::Fn(_, _, ast::Fn { sig, .. }) = kind
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&& let ast::FnRetTy::Ty(ty) = &sig.decl.output
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{
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let mut lt_finder =
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LifetimeFinder { lifetime: lt.span, found: None, seen: vec![] };
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lt_finder.visit_ty(&ty);
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if let [Ty { span, kind: TyKind::Ref(_, mut_ty), .. }] =
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<_finder.seen[..]
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{
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// We might have a situation like
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// fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()>
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// but `lt.span` only points at `'_`, so to suggest `-> Option<()>`
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// we need to find a more accurate span to end up with
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// fn g<'a>(mut x: impl Iterator<Item = &'_ ()>) -> Option<()>
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sugg = vec![(span.with_hi(mut_ty.ty.span.lo()), String::new())];
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owned_sugg = true;
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for param in &sig.decl.inputs {
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lt_finder.visit_ty(¶m.ty);
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}
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if let ast::FnRetTy::Ty(ret_ty) = &sig.decl.output {
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lt_finder.visit_ty(ret_ty);
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let mut ret_lt_finder =
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LifetimeFinder { lifetime: lt.span, found: None, seen: vec![] };
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ret_lt_finder.visit_ty(ret_ty);
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if let [Ty { span, kind: TyKind::Ref(_, mut_ty), .. }] =
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&ret_lt_finder.seen[..]
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{
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// We might have a situation like
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// fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()>
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// but `lt.span` only points at `'_`, so to suggest `-> Option<()>`
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// we need to find a more accurate span to end up with
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// fn g<'a>(mut x: impl Iterator<Item = &'_ ()>) -> Option<()>
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sugg = vec![(span.with_hi(mut_ty.ty.span.lo()), String::new())];
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owned_sugg = true;
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}
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}
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if let Some(ty) = lt_finder.found {
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if let TyKind::Path(None, path) = &ty.kind {
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@ -4098,6 +4105,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
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lt.span.with_hi(ty.span.hi()),
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"String".to_string(),
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)];
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sugg_is_str_to_string = true;
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}
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Some(Res::PrimTy(..)) => {}
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Some(Res::Def(
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@ -4124,6 +4132,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
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lt.span.with_hi(ty.span.hi()),
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"String".to_string(),
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)];
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sugg_is_str_to_string = true;
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}
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Res::PrimTy(..) => {}
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Res::Def(
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@ -4158,6 +4167,12 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
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}
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}
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if owned_sugg {
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if let Some(span) =
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self.find_ref_prefix_span_for_owned_suggestion(lt.span)
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&& !sugg_is_str_to_string
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{
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sugg = vec![(span, String::new())];
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}
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err.multipart_suggestion_verbose(
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format!("{pre} to return an owned value"),
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sugg,
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@ -4184,6 +4199,23 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
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}
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}
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}
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fn find_ref_prefix_span_for_owned_suggestion(&self, lifetime: Span) -> Option<Span> {
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let mut finder = RefPrefixSpanFinder { lifetime, span: None };
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if let Some(item) = self.diag_metadata.current_item {
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finder.visit_item(item);
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} else if let Some((kind, _span)) = self.diag_metadata.current_function
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&& let FnKind::Fn(_, _, ast::Fn { sig, .. }) = kind
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{
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for param in &sig.decl.inputs {
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finder.visit_ty(¶m.ty);
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}
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if let ast::FnRetTy::Ty(ret_ty) = &sig.decl.output {
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finder.visit_ty(ret_ty);
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}
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}
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finder.span
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}
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}
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fn mk_where_bound_predicate(
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@ -4285,6 +4317,26 @@ impl<'ast> Visitor<'ast> for LifetimeFinder<'ast> {
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}
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}
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struct RefPrefixSpanFinder {
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lifetime: Span,
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span: Option<Span>,
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}
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impl<'ast> Visitor<'ast> for RefPrefixSpanFinder {
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fn visit_ty(&mut self, t: &'ast Ty) {
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if self.span.is_some() {
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return;
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}
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if let TyKind::Ref(_, mut_ty) | TyKind::PinnedRef(_, mut_ty) = &t.kind
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&& t.span.lo() == self.lifetime.lo()
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{
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self.span = Some(t.span.with_hi(mut_ty.ty.span.lo()));
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return;
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}
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walk_ty(self, t);
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}
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}
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/// Shadowing involving a label is only a warning for historical reasons.
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//FIXME: make this a proper lint.
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pub(super) fn signal_label_shadowing(sess: &Session, orig: Span, shadower: Ident) {
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29
tests/ui/lifetimes/mut-ref-owned-suggestion.rs
Normal file
29
tests/ui/lifetimes/mut-ref-owned-suggestion.rs
Normal file
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@ -0,0 +1,29 @@
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//! Regression test for <https://github.com/rust-lang/rust/issues/150077>
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//! Tests that `&mut T` suggests `T`, not `mut T`, `&mut str` suggests `String`, not `str`,
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//! when recommending an owned value.
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fn with_fn(_f: impl Fn() -> &mut ()) {}
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//~^ ERROR: missing lifetime specifier
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fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
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//~^ ERROR: missing lifetime specifier
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fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
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//~^ ERROR: missing lifetime specifier
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2
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}
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fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
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//~^ ERROR: missing lifetime specifier
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fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
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//~^ ERROR: missing lifetime specifier
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fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
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//~^ ERROR: missing lifetime specifier
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struct Holder<F: Fn() -> &mut i32> {
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//~^ ERROR: missing lifetime specifier
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f: F,
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}
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fn main() {}
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137
tests/ui/lifetimes/mut-ref-owned-suggestion.stderr
Normal file
137
tests/ui/lifetimes/mut-ref-owned-suggestion.stderr
Normal file
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@ -0,0 +1,137 @@
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:4:29
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LL | fn with_fn(_f: impl Fn() -> &mut ()) {}
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn with_fn(_f: impl Fn() -> &'static mut ()) {}
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| +++++++
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help: instead, you are more likely to want to return an owned value
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LL - fn with_fn(_f: impl Fn() -> &mut ()) {}
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LL + fn with_fn(_f: impl Fn() -> ()) {}
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:7:38
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LL | fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn with_ref_mut_str(_f: impl Fn() -> &'static mut str) {}
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| +++++++
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help: instead, you are more likely to want to return an owned value
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LL - fn with_ref_mut_str(_f: impl Fn() -> &mut str) {}
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LL + fn with_ref_mut_str(_f: impl Fn() -> String) {}
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:10:40
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LL | fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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= note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn with_fn_has_return(_f: impl Fn() -> &'static mut ()) -> i32 {
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| +++++++
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help: consider making the bound lifetime-generic with a new `'a` lifetime
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LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
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LL + fn with_fn_has_return(_f: impl for<'a> Fn() -> &'a ()) -> i32 {
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help: consider introducing a named lifetime parameter
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LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
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LL + fn with_fn_has_return<'a>(_f: impl Fn() -> &'a ()) -> i32 {
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help: alternatively, you might want to return an owned value
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LL - fn with_fn_has_return(_f: impl Fn() -> &mut ()) -> i32 {
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LL + fn with_fn_has_return(_f: impl Fn() -> ()) -> i32 {
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:15:33
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LL | fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn with_dyn(_f: Box<dyn Fn() -> &'static mut i32>) {}
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| +++++++
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help: instead, you are more likely to want to return an owned value
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LL - fn with_dyn(_f: Box<dyn Fn() -> &mut i32>) {}
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LL + fn with_dyn(_f: Box<dyn Fn() -> i32>) {}
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:18:27
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LL | fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn trait_bound<F: Fn() -> &'static mut i32>(_f: F) {}
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| +++++++
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help: instead, you are more likely to want to change the argument to be borrowed...
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LL | fn trait_bound<F: Fn() -> &mut i32>(_f: &F) {}
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| +
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help: ...or alternatively, you might want to return an owned value
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LL - fn trait_bound<F: Fn() -> &mut i32>(_f: F) {}
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LL + fn trait_bound<F: Fn() -> i32>(_f: F) {}
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:21:42
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LL | fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | fn nested_result(_f: impl Fn() -> Result<&'static mut i32, ()>) {}
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| +++++++
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help: instead, you are more likely to want to return an owned value
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LL - fn nested_result(_f: impl Fn() -> Result<&mut i32, ()>) {}
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LL + fn nested_result(_f: impl Fn() -> Result<i32, ()>) {}
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error[E0106]: missing lifetime specifier
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--> $DIR/mut-ref-owned-suggestion.rs:24:26
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LL | struct Holder<F: Fn() -> &mut i32> {
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| ^ expected named lifetime parameter
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= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
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help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
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LL | struct Holder<F: Fn() -> &'static mut i32> {
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| +++++++
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help: instead, you are more likely to want to return an owned value
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LL - struct Holder<F: Fn() -> &mut i32> {
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LL + struct Holder<F: Fn() -> i32> {
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error: aborting due to 7 previous errors
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For more information about this error, try `rustc --explain E0106`.
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