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Alternative wording for inference failure

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estebank committed May 30, 2019
1 parent 8bb094d commit 65c2a7b18bb34547de7c716ace2e8878c2676794
@@ -15,7 +15,7 @@ struct FindLocalByTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
hir_map: &'a hir::map::Map<'gcx>,
found_local_pattern: Option<&'gcx Pat>,
found_arg_pattern: Option<&'gcx Pat>,
found_ty: Option<Ty<'tcx>>,
found_ty: Option<String>,
}

impl<'a, 'gcx, 'tcx> FindLocalByTypeVisitor<'a, 'gcx, 'tcx> {
@@ -55,7 +55,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindLocalByTypeVisitor<'a, 'gcx, 'tcx> {
fn visit_local(&mut self, local: &'gcx Local) {
if let (None, Some(ty)) = (self.found_local_pattern, self.node_matches_type(local.hir_id)) {
self.found_local_pattern = Some(&*local.pat);
self.found_ty = Some(ty);
self.found_ty = Some(ty.to_string());
}
intravisit::walk_local(self, local);
}
@@ -67,7 +67,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindLocalByTypeVisitor<'a, 'gcx, 'tcx> {
self.node_matches_type(argument.hir_id),
) {
self.found_arg_pattern = Some(&*argument.pat);
self.found_ty = Some(ty);
self.found_ty = Some(ty.to_string());
}
}
intravisit::walk_body(self, body);
@@ -108,7 +108,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
let name = self.extract_type_name(&ty, None);

let mut err_span = span;
let mut labels = vec![(span, InferCtxt::missing_type_msg(&name))];

let mut local_visitor = FindLocalByTypeVisitor {
infcx: &self,
@@ -124,10 +123,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
local_visitor.visit_expr(expr);
}

let ty_msg = match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(" for `{}`", ty),
let ty_msg = match &local_visitor.found_ty {
Some(ty) if &ty[..] != "_" && ty != &name => format!(" in `{}`", ty),
_ => String::new(),
};
let mut labels = vec![(span, InferCtxt::missing_type_msg(&name, &ty_msg))];

if let Some(pattern) = local_visitor.found_arg_pattern {
err_span = pattern.span;
// We don't want to show the default label for closures.
@@ -148,8 +149,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
labels.clear();
labels.push((pattern.span, format!(
"consider giving this closure parameter {}",
match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(
match &local_visitor.found_ty {
Some(ty) if &ty[..] != "_" && ty != &name => format!(
"the type `{}` with the type parameter `{}` specified",
ty,
name,
@@ -162,18 +163,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
match pattern.span.compiler_desugaring_kind() {
None => labels.push((
pattern.span,
format!(
"consider giving `{}` {}",
simple_ident,
match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(
"the type `{}` with the type parameter `{}` specified",
ty,
name,
),
_ => "a type".to_owned(),
},
),
format!("consider giving `{}` a type", simple_ident),
)),
Some(CompilerDesugaringKind::ForLoop) => labels.push((
pattern.span,
@@ -213,15 +203,15 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
span,
E0698,
"type inside generator must be known in this context");
err.span_label(span, InferCtxt::missing_type_msg(&name));
err.span_label(span, InferCtxt::missing_type_msg(&name, ""));
err
}

fn missing_type_msg(type_name: &str) -> String {
fn missing_type_msg(type_name: &str, postfix: &str) -> String {
if type_name == "_" {
"cannot infer type".to_owned()
} else {
format!("cannot infer type for `{}`", type_name)
format!("cannot infer type for `{}`{}", type_name, postfix)
}
}
}
@@ -1,4 +1,4 @@
error[E0282]: type annotations needed for `&_`
error[E0282]: type annotations needed in `&_`
--> $DIR/issue-12187-1.rs:6:10
|
LL | let &v = new();
@@ -1,4 +1,4 @@
error[E0282]: type annotations needed for `&_`
error[E0282]: type annotations needed in `&_`
--> $DIR/issue-12187-2.rs:6:10
|
LL | let &v = new();
@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `B<_>`
error[E0282]: type annotations needed in `B<_>`
--> $DIR/issue-17551.rs:6:15
|
LL | let foo = B(marker::PhantomData);
| --- ^ cannot infer type for `T`
| --- ^ cannot infer type for `T` in `B<_>`
| |
| consider giving `foo` the type `B<_>` with the type parameter `T` specified
| consider giving `foo` a type

error: aborting due to previous error

@@ -1,4 +1,4 @@
error[E0282]: type annotations needed for `&(_,)`
error[E0282]: type annotations needed in `&(_,)`
--> $DIR/issue-20261.rs:4:11
|
LL | for (ref i,) in [].iter() {
@@ -1,4 +1,4 @@
error[E0282]: type annotations needed for `Expr<'_, _>`
error[E0282]: type annotations needed in `Expr<'_, _>`
--> $DIR/issue-23046.rs:17:15
|
LL | let ex = |x| {
@@ -1,11 +1,11 @@
error[E0282]: type annotations needed for `(std::sync::mpsc::Sender<Foo<_>>, std::sync::mpsc::Receiver<Foo<_>>)`
error[E0282]: type annotations needed in `(std::sync::mpsc::Sender<Foo<_>>, std::sync::mpsc::Receiver<Foo<_>>)`
--> $DIR/issue-25368.rs:11:17
|
LL | let (tx, rx) = channel();
| -------- consider giving the pattern a type
...
LL | tx.send(Foo{ foo: PhantomData });
| ^^^ cannot infer type for `T`
| ^^^ cannot infer type for `T` in `(std::sync::mpsc::Sender<Foo<_>>, std::sync::mpsc::Receiver<Foo<_>>)`

error: aborting due to previous error

@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `&[_; 0]`
error[E0282]: type annotations needed in `&[_; 0]`
--> $DIR/issue-7813.rs:2:13
|
LL | let v = &[];
| - ^^^ cannot infer type
| |
| consider giving `v` the type `&[_; 0]` with the type parameter `_` specified
| consider giving `v` a type

error: aborting due to previous error

@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `std::vec::Vec<_>`
error[E0282]: type annotations needed in `std::vec::Vec<_>`
--> $DIR/method-ambig-one-trait-unknown-int-type.rs:24:17
|
LL | let mut x = Vec::new();
| ----- ^^^^^^^^ cannot infer type for `T`
| ----- ^^^^^^^^ cannot infer type for `T` in `std::vec::Vec<_>`
| |
| consider giving `x` the type `std::vec::Vec<_>` with the type parameter `T` specified
| consider giving `x` a type

error[E0308]: mismatched types
--> $DIR/method-ambig-one-trait-unknown-int-type.rs:33:20
@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `std::option::Option<_>`
error[E0282]: type annotations needed in `std::option::Option<_>`
--> $DIR/issue-42234-unknown-receiver-type.rs:7:5
|
LL | let x: Option<_> = None;
| - consider giving `x` the type `std::option::Option<_>` with the type parameter `T` specified
| - consider giving `x` a type
LL | x.unwrap().method_that_could_exist_on_some_type();
| ^^^^^^^^^^ cannot infer type for `T`
| ^^^^^^^^^^ cannot infer type for `T` in `std::option::Option<_>`
|
= note: type must be known at this point

@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `[_; 0]`
error[E0282]: type annotations needed in `[_; 0]`
--> $DIR/cannot_infer_local_or_array.rs:2:13
|
LL | let x = [];
| - ^^ cannot infer type
| |
| consider giving `x` the type `[_; 0]` with the type parameter `_` specified
| consider giving `x` a type

error: aborting due to previous error

@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `std::vec::Vec<_>`
error[E0282]: type annotations needed in `std::vec::Vec<_>`
--> $DIR/cannot_infer_local_or_vec.rs:2:13
|
LL | let x = vec![];
| - ^^^^^^ cannot infer type for `T`
| - ^^^^^^ cannot infer type for `T` in `std::vec::Vec<_>`
| |
| consider giving `x` the type `std::vec::Vec<_>` with the type parameter `T` specified
| consider giving `x` a type
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

@@ -1,8 +1,8 @@
error[E0282]: type annotations needed for `(std::vec::Vec<_>,)`
error[E0282]: type annotations needed in `(std::vec::Vec<_>,)`
--> $DIR/cannot_infer_local_or_vec_in_tuples.rs:2:18
|
LL | let (x, ) = (vec![], );
| ----- ^^^^^^ cannot infer type for `T`
| ----- ^^^^^^ cannot infer type for `T` in `(std::vec::Vec<_>,)`
| |
| consider giving the pattern a type
|
@@ -1,8 +1,8 @@
error[E0282]: type annotations needed for `std::option::Option<_>`
error[E0282]: type annotations needed in `std::option::Option<_>`
--> $DIR/unboxed-closures-failed-recursive-fn-2.rs:16:32
|
LL | let mut closure0 = None;
| ------------ consider giving `closure0` the type `std::option::Option<_>` with the type parameter `_` specified
| ------------ consider giving `closure0` a type
...
LL | return c();
| ^^^ cannot infer type
@@ -1,10 +1,10 @@
error[E0282]: type annotations needed for `std::vec::Vec<_>`
error[E0282]: type annotations needed in `std::vec::Vec<_>`
--> $DIR/vector-no-ann.rs:2:16
|
LL | let _foo = Vec::new();
| ---- ^^^^^^^^ cannot infer type for `T`
| ---- ^^^^^^^^ cannot infer type for `T` in `std::vec::Vec<_>`
| |
| consider giving `_foo` the type `std::vec::Vec<_>` with the type parameter `T` specified
| consider giving `_foo` a type

error: aborting due to previous error

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