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Rollup merge of rust-lang#67285 - ohadravid:indicate-origin-of-where-…
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…type-parameter, r=estebank

Indicate origin of where type parameter for uninferred types

Based on rust-lang#65951 (which is not merge yet), fixes rust-lang#67277.

This PR improves a little the diagnostic for code like:

```
 async fn foo() {
     bar().await;
}

 async fn bar<T>() -> () {}
```

by showing:
```
error[E0698]: type inside `async fn` body must be known in this context
 --> unresolved_type_param.rs:9:5
  |
9 |     bar().await;
  |     ^^^ cannot infer type for type parameter `T` declared on the function `bar`
  |
...
```
(The
```
declared on the function `bar`
```
part is new)

A small side note: `Vec` and `slice` seem to resist this change, because querying `item_name()` panics, and `get_opt_name()` returns `None`.

r? @estebank
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Centril authored Dec 15, 2019
2 parents 3765295 + 8a4632d commit 3a94151
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Showing 28 changed files with 97 additions and 41 deletions.
78 changes: 65 additions & 13 deletions src/librustc/infer/error_reporting/need_type_info.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use crate::hir::{self, Body, FunctionRetTy, Expr, ExprKind, HirId, Local, Pat};
use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
use crate::infer::InferCtxt;
use crate::infer::type_variable::TypeVariableOriginKind;
use crate::ty::{self, Ty, Infer, TyVar};
use crate::ty::{self, Ty, Infer, TyVar, DefIdTree};
use crate::ty::print::Print;
use syntax::source_map::DesugaringKind;
use syntax::symbol::kw;
Expand Down Expand Up @@ -117,6 +117,8 @@ fn closure_return_type_suggestion(
descr: &str,
name: &str,
ret: &str,
parent_name: Option<String>,
parent_descr: Option<&str>,
) {
let (arrow, post) = match output {
FunctionRetTy::DefaultReturn(_) => ("-> ", " "),
Expand All @@ -138,7 +140,12 @@ fn closure_return_type_suggestion(
suggestion,
Applicability::HasPlaceholders,
);
err.span_label(span, InferCtxt::missing_type_msg(&name, &descr));
err.span_label(span, InferCtxt::missing_type_msg(
&name,
&descr,
parent_name,
parent_descr
));
}

/// Given a closure signature, return a `String` containing a list of all its argument types.
Expand Down Expand Up @@ -177,16 +184,31 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
&self,
ty: Ty<'tcx>,
highlight: Option<ty::print::RegionHighlightMode>,
) -> (String, Option<Span>, Cow<'static, str>) {
) -> (String, Option<Span>, Cow<'static, str>, Option<String>, Option<&'static str>) {
if let ty::Infer(ty::TyVar(ty_vid)) = ty.kind {
let ty_vars = self.type_variables.borrow();
let var_origin = ty_vars.var_origin(ty_vid);
if let TypeVariableOriginKind::TypeParameterDefinition(name) = var_origin.kind {
if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) = var_origin.kind {
let parent_def_id = def_id.and_then(|def_id| self.tcx.parent(def_id));
let (parent_name, parent_desc) = if let Some(parent_def_id) = parent_def_id {
let parent_name = self.tcx.def_key(parent_def_id).disambiguated_data.data
.get_opt_name().map(|parent_symbol| parent_symbol.to_string());

let type_parent_desc = self.tcx.def_kind(parent_def_id)
.map(|parent_def_kind| parent_def_kind.descr(parent_def_id));

(parent_name, type_parent_desc)
} else {
(None, None)
};

if name != kw::SelfUpper {
return (
name.to_string(),
Some(var_origin.span),
"type parameter".into(),
parent_name,
parent_desc,
);
}
}
Expand All @@ -198,7 +220,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
printer.region_highlight_mode = highlight;
}
let _ = ty.print(printer);
(s, None, ty.prefix_string())
(s, None, ty.prefix_string(), None, None)
}

pub fn need_type_info_err(
Expand All @@ -209,7 +231,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
error_code: TypeAnnotationNeeded,
) -> DiagnosticBuilder<'tcx> {
let ty = self.resolve_vars_if_possible(&ty);
let (name, name_sp, descr) = self.extract_type_name(&ty, None);
let (name, name_sp, descr, parent_name, parent_descr) = self.extract_type_name(&ty, None);


let mut local_visitor = FindLocalByTypeVisitor::new(&self, ty, &self.tcx.hir());
let ty_to_string = |ty: Ty<'tcx>| -> String {
Expand All @@ -218,7 +241,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
let ty_vars = self.type_variables.borrow();
let getter = move |ty_vid| {
let var_origin = ty_vars.var_origin(ty_vid);
if let TypeVariableOriginKind::TypeParameterDefinition(name) = var_origin.kind {
if let TypeVariableOriginKind::TypeParameterDefinition(name, _) = var_origin.kind {
return Some(name.to_string());
}
None
Expand Down Expand Up @@ -317,6 +340,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
&descr,
&name,
&ret,
parent_name,
parent_descr,
);
// We don't want to give the other suggestions when the problem is the
// closure return type.
Expand Down Expand Up @@ -433,8 +458,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
if !err.span.span_labels().iter().any(|span_label| {
span_label.label.is_some() && span_label.span == span
}) && local_visitor.found_arg_pattern.is_none()
{ // Avoid multiple labels pointing at `span`.
err.span_label(span, InferCtxt::missing_type_msg(&name, &descr));
{
// Avoid multiple labels pointing at `span`.
err.span_label(
span,
InferCtxt::missing_type_msg(&name, &descr, parent_name, parent_descr)
);
}

err
Expand Down Expand Up @@ -496,19 +525,42 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
ty: Ty<'tcx>,
) -> DiagnosticBuilder<'tcx> {
let ty = self.resolve_vars_if_possible(&ty);
let (name, _, descr) = self.extract_type_name(&ty, None);
let (name, _, descr, parent_name, parent_descr) = self.extract_type_name(&ty, None);

let mut err = struct_span_err!(
self.tcx.sess, span, E0698, "type inside {} must be known in this context", kind,
);
err.span_label(span, InferCtxt::missing_type_msg(&name, &descr));
err.span_label(span, InferCtxt::missing_type_msg(
&name,
&descr,
parent_name,
parent_descr
));
err
}

fn missing_type_msg(type_name: &str, descr: &str) -> Cow<'static, str>{
fn missing_type_msg(
type_name: &str,
descr: &str,
parent_name: Option<String>,
parent_descr: Option<&str>,
) -> Cow<'static, str> {
if type_name == "_" {
"cannot infer type".into()
} else {
format!("cannot infer type for {} `{}`", descr, type_name).into()
let parent_desc = if let Some(parent_name) = parent_name {
let parent_type_descr = if let Some(parent_descr) = parent_descr {
format!(" the {}", parent_descr)
} else {
"".into()
};

format!(" declared on{} `{}`", parent_type_descr, parent_name)
} else {
"".to_string()
};

format!("cannot infer type for {} `{}`{}", descr, type_name, parent_desc).into()
}
}
}
5 changes: 4 additions & 1 deletion src/librustc/infer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1135,7 +1135,10 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
self.universe(),
false,
TypeVariableOrigin {
kind: TypeVariableOriginKind::TypeParameterDefinition(param.name),
kind: TypeVariableOriginKind::TypeParameterDefinition(
param.name,
Some(param.def_id)
),
span,
},
);
Expand Down
2 changes: 1 addition & 1 deletion src/librustc/infer/resolve.rs
Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for UnresolvedTypeFinder<'a, 'tcx> {
if let ty::TyVar(ty_vid) = infer_ty {
let ty_vars = self.infcx.type_variables.borrow();
if let TypeVariableOrigin {
kind: TypeVariableOriginKind::TypeParameterDefinition(_),
kind: TypeVariableOriginKind::TypeParameterDefinition(_, _),
span,
} = *ty_vars.var_origin(ty_vid)
{
Expand Down
3 changes: 2 additions & 1 deletion src/librustc/infer/type_variable.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use syntax::symbol::Symbol;
use syntax_pos::Span;
use crate::ty::{self, Ty, TyVid};
use crate::hir::def_id::DefId;

use std::cmp;
use std::marker::PhantomData;
Expand Down Expand Up @@ -49,7 +50,7 @@ pub enum TypeVariableOriginKind {
MiscVariable,
NormalizeProjectionType,
TypeInference,
TypeParameterDefinition(Symbol),
TypeParameterDefinition(Symbol, Option<DefId>),

/// One of the upvars or closure kind parameters in a `ClosureSubsts`
/// (before it has been determined).
Expand Down
2 changes: 1 addition & 1 deletion src/librustc/traits/error_reporting.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2113,7 +2113,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
self.var_map.entry(ty).or_insert_with(||
infcx.next_ty_var(
TypeVariableOrigin {
kind: TypeVariableOriginKind::TypeParameterDefinition(name),
kind: TypeVariableOriginKind::TypeParameterDefinition(name, None),
span: DUMMY_SP,
}
)
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/async-await/unresolved_type_param.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0698]: type inside `async fn` body must be known in this context
--> $DIR/unresolved_type_param.rs:9:5
|
LL | bar().await;
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the function `bar`
|
note: the type is part of the `async fn` body because of this `await`
--> $DIR/unresolved_type_param.rs:9:5
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/const-generics/fn-const-param-infer.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ error[E0282]: type annotations needed
--> $DIR/fn-const-param-infer.rs:22:23
|
LL | let _ = Checked::<generic>;
| ^^^^^^^ cannot infer type for type parameter `T`
| ^^^^^^^ cannot infer type for type parameter `T` declared on the function `generic`

error[E0308]: mismatched types
--> $DIR/fn-const-param-infer.rs:25:40
Expand Down
4 changes: 2 additions & 2 deletions src/test/ui/consts/issue-64662.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,13 @@ error[E0282]: type annotations needed
--> $DIR/issue-64662.rs:2:9
|
LL | A = foo(),
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the function `foo`

error[E0282]: type annotations needed
--> $DIR/issue-64662.rs:3:9
|
LL | B = foo(),
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the function `foo`

error: aborting due to 2 previous errors

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/error-codes/E0401.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ error[E0282]: type annotations needed
--> $DIR/E0401.rs:11:5
|
LL | bfnr(x);
| ^^^^ cannot infer type for type parameter `U`
| ^^^^ cannot infer type for type parameter `U` declared on the function `bfnr`

error: aborting due to 4 previous errors

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-12028.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0284]: type annotations needed
--> $DIR/issue-12028.rs:27:14
|
LL | self.input_stream(&mut stream);
| ^^^^^^^^^^^^ cannot infer type for type parameter `H`
| ^^^^^^^^^^^^ cannot infer type for type parameter `H` declared on the trait `StreamHash`
|
= note: cannot resolve `<_ as StreamHasher>::S == <H as StreamHasher>::S`

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-16966.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/issue-16966.rs:2:5
|
LL | panic!(std::default::Default::default());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `M`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `M` declared on the function `begin_panic`
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-17551.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed for `B<T>`
--> $DIR/issue-17551.rs:6:15
|
LL | let foo = B(marker::PhantomData);
| --- ^ cannot infer type for type parameter `T`
| --- ^ cannot infer type for type parameter `T` declared on the struct `B`
| |
| consider giving `foo` the explicit type `B<T>`, where the type parameter `T` is specified

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-25368.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ LL | let (tx, rx) = channel();
| -------- consider giving this pattern the explicit type `(std::sync::mpsc::Sender<Foo<T>>, std::sync::mpsc::Receiver<Foo<T>>)`, where the type parameter `T` is specified
...
LL | tx.send(Foo{ foo: PhantomData });
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the struct `Foo`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-5062.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/issue-5062.rs:1:29
|
LL | fn main() { format!("{:?}", None); }
| ^^^^ cannot infer type for type parameter `T`
| ^^^^ cannot infer type for type parameter `T` declared on the enum `Option`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-6458-2.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/issue-6458-2.rs:3:21
|
LL | format!("{:?}", None);
| ^^^^ cannot infer type for type parameter `T`
| ^^^^ cannot infer type for type parameter `T` declared on the enum `Option`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-6458-3.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/issue-6458-3.rs:4:5
|
LL | mem::transmute(0);
| ^^^^^^^^^^^^^^ cannot infer type for type parameter `U`
| ^^^^^^^^^^^^^^ cannot infer type for type parameter `U` declared on the function `transmute`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-6458.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/issue-6458.rs:9:4
|
LL | foo(TypeWithState(marker::PhantomData));
| ^^^ cannot infer type for type parameter `State`
| ^^^ cannot infer type for type parameter `State` declared on the function `foo`

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/missing-type-parameter.rs:4:5
|
LL | foo();
| ^^^ cannot infer type for type parameter `X`
| ^^^ cannot infer type for type parameter `X` declared on the function `foo`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/span/type-annotations-needed-expr.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ error[E0282]: type annotations needed
LL | let _ = (vec![1,2,3]).into_iter().sum() as f64;
| ^^^
| |
| cannot infer type for type parameter `S`
| cannot infer type for type parameter `S` declared on the method `sum`
| help: consider specifying the type argument in the method call: `sum::<S>`
|
= note: type must be known at this point
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/traits-multidispatch-convert-ambig-dest.rs:26:5
|
LL | test(22, std::default::Default::default());
| ^^^^ cannot infer type for type parameter `U`
| ^^^^ cannot infer type for type parameter `U` declared on the function `test`

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ error[E0282]: type annotations needed
LL | .or_else(|err| {
| ^^^^^^^
| |
| cannot infer type for type parameter `F`
| cannot infer type for type parameter `F` declared on the method `or_else`
| help: consider specifying the type arguments in the method call: `or_else::<F, O>`

error: aborting due to previous error
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/type-inference/sort_by_key.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ error[E0282]: type annotations needed
LL | lst.sort_by_key(|&(v, _)| v.iter().sum());
| ^^^^^^^^^^^ --- help: consider specifying the type argument in the method call: `sum::<S>`
| |
| cannot infer type for type parameter `K`
| cannot infer type for type parameter `K` declared on the method `sort_by_key`

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ LL | S(std::marker::PhantomData).foo();
| ^--------------------------------
| |
| this method call resolves to `<Self as T>::A`
| cannot infer type for type parameter `X`
| cannot infer type for type parameter `X` declared on the struct `S`

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/unbounded-type-param-in-fn-with-assoc-type.rs:8:5
|
LL | foo();
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the function `foo`

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ error[E0282]: type annotations needed
--> $DIR/unbounded-type-param-in-fn.rs:6:5
|
LL | foo();
| ^^^ cannot infer type for type parameter `T`
| ^^^ cannot infer type for type parameter `T` declared on the function `foo`

error: aborting due to previous error

Expand Down
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