predicates
.iter()
.map(|(param, constraint)| (param.name.as_str(), &**constraint, None)),
+ None,
);
}
}
¶m_ty.name.as_str(),
&constraint,
None,
+ None,
);
}
}
bounds.iter().map(|(param, constraint, def_id)| {
(param.as_str(), constraint.as_str(), *def_id)
}),
+ None,
);
err.emit();
}
generics,
diag,
vec![(param.name.as_str(), "Clone", Some(clone_trait_did))].into_iter(),
+ None,
);
} else {
self.suggest_derive(diag, &[(trait_ref.to_predicate(self.tcx), None, None)]);
(ty::Param(p), ty::Alias(ty::Projection, proj)) | (ty::Alias(ty::Projection, proj), ty::Param(p))
if tcx.def_kind(proj.def_id) != DefKind::ImplTraitPlaceholder =>
{
- let generics = tcx.generics_of(body_owner_def_id);
- let p_span = tcx.def_span(generics.type_param(p, tcx).def_id);
+ let p_def_id = tcx
+ .generics_of(body_owner_def_id)
+ .type_param(p, tcx)
+ .def_id;
+ let p_span = tcx.def_span(p_def_id);
if !sp.contains(p_span) {
diag.span_label(p_span, "this type parameter");
}
let hir = tcx.hir();
let mut note = true;
- if let Some(generics) = generics
- .type_param(p, tcx)
- .def_id
+ let parent = p_def_id
.as_local()
- .map(|id| hir.local_def_id_to_hir_id(id))
- .and_then(|id| tcx.hir().find_parent(id))
- .as_ref()
- .and_then(|node| node.generics())
+ .and_then(|id| {
+ let local_id = hir.local_def_id_to_hir_id(id);
+ let generics = tcx.hir().find_parent(local_id)?.generics()?;
+ Some((id, generics))
+ });
+ if let Some((local_id, generics)) = parent
{
// Synthesize the associated type restriction `Add<Output = Expected>`.
// FIXME: extract this logic for use in other diagnostics.
let (trait_ref, assoc_substs) = proj.trait_ref_and_own_substs(tcx);
- let path =
- tcx.def_path_str_with_substs(trait_ref.def_id, trait_ref.substs);
let item_name = tcx.item_name(proj.def_id);
let item_args = self.format_generic_args(assoc_substs);
- let path = if path.ends_with('>') {
- format!(
- "{}, {}{} = {}>",
- &path[..path.len() - 1],
- item_name,
- item_args,
- p
- )
+ // Here, we try to see if there's an existing
+ // trait implementation that matches the one that
+ // we're suggesting to restrict. If so, find the
+ // "end", whether it be at the end of the trait
+ // or the end of the generic arguments.
+ let mut matching_span = None;
+ let mut matched_end_of_args = false;
+ for bound in generics.bounds_for_param(local_id) {
+ let potential_spans = bound
+ .bounds
+ .iter()
+ .find_map(|bound| {
+ let bound_trait_path = bound.trait_ref()?.path;
+ let def_id = bound_trait_path.res.opt_def_id()?;
+ let generic_args = bound_trait_path.segments.iter().last().map(|path| path.args());
+ (def_id == trait_ref.def_id).then_some((bound_trait_path.span, generic_args))
+ });
+
+ if let Some((end_of_trait, end_of_args)) = potential_spans {
+ let args_span = end_of_args.and_then(|args| args.span());
+ matched_end_of_args = args_span.is_some();
+ matching_span = args_span
+ .or_else(|| Some(end_of_trait))
+ .map(|span| span.shrink_to_hi());
+ break;
+ }
+ }
+
+ if matched_end_of_args {
+ // Append suggestion to the end of our args
+ let path = format!(", {}{} = {}",item_name, item_args, p);
+ note = !suggest_constraining_type_param(
+ tcx,
+ generics,
+ diag,
+ &format!("{}", proj.self_ty()),
+ &path,
+ None,
+ matching_span,
+ );
} else {
- format!("{}<{}{} = {}>", path, item_name, item_args, p)
- };
- note = !suggest_constraining_type_param(
- tcx,
- generics,
- diag,
- &format!("{}", proj.self_ty()),
- &path,
- None,
- );
+ // Suggest adding a bound to an existing trait
+ // or if the trait doesn't exist, add the trait
+ // and the suggested bounds.
+ let path = format!("<{}{} = {}>", item_name, item_args, p);
+ note = !suggest_constraining_type_param(
+ tcx,
+ generics,
+ diag,
+ &format!("{}", proj.self_ty()),
+ &path,
+ None,
+ matching_span,
+ );
+ }
}
if note {
diag.note("you might be missing a type parameter or trait bound");
}
/// Suggest restricting a type param with a new bound.
+///
+/// If `span_to_replace` is provided, then that span will be replaced with the
+/// `constraint`. If one wasn't provided, then the full bound will be suggested.
pub fn suggest_constraining_type_param(
tcx: TyCtxt<'_>,
generics: &hir::Generics<'_>,
param_name: &str,
constraint: &str,
def_id: Option<DefId>,
+ span_to_replace: Option<Span>,
) -> bool {
suggest_constraining_type_params(
tcx,
generics,
err,
[(param_name, constraint, def_id)].into_iter(),
+ span_to_replace,
)
}
generics: &hir::Generics<'_>,
err: &mut Diagnostic,
param_names_and_constraints: impl Iterator<Item = (&'a str, &'a str, Option<DefId>)>,
+ span_to_replace: Option<Span>,
) -> bool {
let mut grouped = FxHashMap::default();
param_names_and_constraints.for_each(|(param_name, constraint, def_id)| {
let mut suggest_restrict = |span, bound_list_non_empty| {
suggestions.push((
span,
- if bound_list_non_empty {
+ if span_to_replace.is_some() {
+ constraint.clone()
+ } else if bound_list_non_empty {
format!(" + {}", constraint)
} else {
format!(" {}", constraint)
))
};
+ if let Some(span) = span_to_replace {
+ suggest_restrict(span, true);
+ continue;
+ }
+
// When the type parameter has been provided bounds
//
// Message:
¶m_name,
&constraint,
Some(trait_pred.def_id()),
+ None,
) {
return;
}
param.name.as_str(),
"Clone",
Some(clone_trait),
+ None,
);
}
err.span_suggestion_verbose(
| ^^^^^^^^^^ required by this bound in `UnsafeCopy`
help: consider further restricting this bound
|
-LL | impl<T: Copy + std::ops::Deref + Deref<Target = T>> UnsafeCopy<'_, T> for T {
- | +++++++++++++++++++
+LL | impl<T: Copy + std::ops::Deref<Target = T>> UnsafeCopy<'_, T> for T {
+ | ++++++++++++
error: aborting due to previous error
| ^^^^^^^^^^ required by this bound in `UnsafeCopy::Item`
help: consider further restricting this bound
|
-LL | impl<T: Copy + std::ops::Deref + Deref<Target = T>> UnsafeCopy<T> for T {
- | +++++++++++++++++++
+LL | impl<T: Copy + std::ops::Deref<Target = T>> UnsafeCopy<T> for T {
+ | ++++++++++++
error: aborting due to previous error
struct A<B>(B);
-impl<B> Add for A<B> where B: Add + Add<Output = B> {
+impl<B> Add for A<B> where B: Add<Output = B> {
type Output = Self;
fn add(self, rhs: Self) -> Self {
struct C<B>(B);
-impl<B: Add + Add<Output = B>> Add for C<B> {
+impl<B: Add<Output = B>> Add for C<B> {
type Output = Self;
fn add(self, rhs: Self) -> Self {
struct E<B>(B);
-impl<B: Add + Add<Output = B>> Add for E<B> where B: Add<Output = B> {
+impl<B: Add<Output = B>> Add for E<B> where B: Add<Output = B> {
//~^ ERROR equality constraints are not yet supported in `where` clauses
type Output = Self;
| ^
help: consider further restricting this bound
|
-LL | impl<B> Add for A<B> where B: Add + Add<Output = B> {
- | +++++++++++++++++
+LL | impl<B> Add for A<B> where B: Add<Output = B> {
+ | ++++++++++++
error[E0308]: mismatched types
--> $DIR/missing-bounds.rs:21:14
| ^
help: consider further restricting this bound
|
-LL | impl<B: Add + Add<Output = B>> Add for C<B> {
- | +++++++++++++++++
+LL | impl<B: Add<Output = B>> Add for C<B> {
+ | ++++++++++++
error[E0369]: cannot add `B` to `B`
--> $DIR/missing-bounds.rs:31:21
| ^
help: consider further restricting this bound
|
-LL | impl<B: Add + Add<Output = B>> Add for E<B> where <B as Add>::Output = B {
- | +++++++++++++++++
+LL | impl<B: Add<Output = B>> Add for E<B> where <B as Add>::Output = B {
+ | ++++++++++++
error: aborting due to 5 previous errors
--- /dev/null
+pub trait TryAdd<Rhs = Self> {
+ type Error;
+ type Output;
+
+ fn try_add(self, rhs: Rhs) -> Result<Self::Output, Self::Error>;
+}
+
+impl<T: TryAdd> TryAdd for Option<T> {
+ type Error = <T as TryAdd>::Error;
+ type Output = Option<<T as TryAdd>::Output>;
+
+ fn try_add(self, rhs: Self) -> Result<Self::Output, Self::Error> {
+ Ok(self) //~ ERROR mismatched types
+ }
+}
+
+struct Other<A>(A);
+
+struct X;
+
+impl<T: TryAdd<Error = X>> TryAdd for Other<T> {
+ type Error = <T as TryAdd>::Error;
+ type Output = Other<<T as TryAdd>::Output>;
+
+ fn try_add(self, rhs: Self) -> Result<Self::Output, Self::Error> {
+ Ok(self) //~ ERROR mismatched types
+ }
+}
+
+fn main() {}
--- /dev/null
+error[E0308]: mismatched types
+ --> $DIR/restrict-existing-type-bounds.rs:13:12
+ |
+LL | impl<T: TryAdd> TryAdd for Option<T> {
+ | - this type parameter
+...
+LL | Ok(self)
+ | -- ^^^^ expected `Option<<T as TryAdd>::Output>`, found `Option<T>`
+ | |
+ | arguments to this enum variant are incorrect
+ |
+ = note: expected enum `Option<<T as TryAdd>::Output>`
+ found enum `Option<T>`
+help: the type constructed contains `Option<T>` due to the type of the argument passed
+ --> $DIR/restrict-existing-type-bounds.rs:13:9
+ |
+LL | Ok(self)
+ | ^^^----^
+ | |
+ | this argument influences the type of `Ok`
+note: tuple variant defined here
+ --> $SRC_DIR/core/src/result.rs:LL:COL
+help: consider further restricting this bound
+ |
+LL | impl<T: TryAdd<Output = T>> TryAdd for Option<T> {
+ | ++++++++++++
+
+error[E0308]: mismatched types
+ --> $DIR/restrict-existing-type-bounds.rs:26:12
+ |
+LL | impl<T: TryAdd<Error = X>> TryAdd for Other<T> {
+ | - this type parameter
+...
+LL | Ok(self)
+ | -- ^^^^ expected `Other<<T as TryAdd>::Output>`, found `Other<T>`
+ | |
+ | arguments to this enum variant are incorrect
+ |
+ = note: expected struct `Other<<T as TryAdd>::Output>`
+ found struct `Other<T>`
+help: the type constructed contains `Other<T>` due to the type of the argument passed
+ --> $DIR/restrict-existing-type-bounds.rs:26:9
+ |
+LL | Ok(self)
+ | ^^^----^
+ | |
+ | this argument influences the type of `Ok`
+note: tuple variant defined here
+ --> $SRC_DIR/core/src/result.rs:LL:COL
+help: consider further restricting this bound
+ |
+LL | impl<T: TryAdd<Error = X, Output = T>> TryAdd for Other<T> {
+ | ++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
projects / rust.git / commitdiff