Auto merge of #52244 - glandium:issue52097, r=estebank

Don't display default generic parameters in diagnostics that compare types

In errors like:
```
   expected type: `RawVec<foo, Global>`
      found type: `foo`
```

`RawVec` being defined as `RawVec<T, A: Alloc = Global>`, the error is better written as
```
   expected type: `RawVec<foo>`
      found type: `foo`
```

In fact, that is already what happens when `foo` is not an ADT, because in that case, the diagnostic handler doesn't try to highlight something, and just uses the `Display` trait instead of its own logic.

e.g.
```
   expected type: `RawVec<usize>`
      found type: `usize`
```
This commit is contained in:
bors 2018-07-14 06:24:42 +00:00
commit 0a8275f8b6
3 changed files with 581 additions and 7 deletions

View File

@ -60,13 +60,13 @@ use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePa
use super::region_constraints::GenericKind;
use super::lexical_region_resolve::RegionResolutionError;
use std::fmt;
use std::{cmp, fmt};
use hir;
use hir::map as hir_map;
use hir::def_id::DefId;
use middle::region;
use traits::{ObligationCause, ObligationCauseCode};
use ty::{self, Region, Ty, TyCtxt, TypeFoldable, TypeVariants};
use ty::{self, subst::Subst, Region, Ty, TyCtxt, TypeFoldable, TypeVariants};
use ty::error::TypeError;
use syntax::ast::DUMMY_NODE_ID;
use syntax_pos::{Pos, Span};
@ -652,6 +652,43 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
}
}
/// For generic types with parameters with defaults, remove the parameters corresponding to
/// the defaults. This repeats a lot of the logic found in `PrintContext::parameterized`.
fn strip_generic_default_params(
&self,
def_id: DefId,
substs: &ty::subst::Substs<'tcx>
) -> &'tcx ty::subst::Substs<'tcx> {
let generics = self.tcx.generics_of(def_id);
let mut num_supplied_defaults = 0;
let mut type_params = generics.params.iter().rev().filter_map(|param| match param.kind {
ty::GenericParamDefKind::Lifetime => None,
ty::GenericParamDefKind::Type { has_default, .. } => {
Some((param.def_id, has_default))
}
}).peekable();
let has_default = {
let has_default = type_params.peek().map(|(_, has_default)| has_default);
*has_default.unwrap_or(&false)
};
if has_default {
let types = substs.types().rev();
for ((def_id, has_default), actual) in type_params.zip(types) {
if !has_default {
break;
}
if self.tcx.type_of(def_id).subst(self.tcx, substs) != actual {
break;
}
num_supplied_defaults += 1;
}
}
let len = generics.params.len();
let mut generics = generics.clone();
generics.params.truncate(len - num_supplied_defaults);
substs.truncate_to(self.tcx, &generics)
}
/// Compare two given types, eliding parts that are the same between them and highlighting
/// relevant differences, and return two representation of those types for highlighted printing.
fn cmp(&self, t1: Ty<'tcx>, t2: Ty<'tcx>) -> (DiagnosticStyledString, DiagnosticStyledString) {
@ -693,6 +730,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
match (&t1.sty, &t2.sty) {
(&ty::TyAdt(def1, sub1), &ty::TyAdt(def2, sub2)) => {
let sub_no_defaults_1 = self.strip_generic_default_params(def1.did, sub1);
let sub_no_defaults_2 = self.strip_generic_default_params(def2.did, sub2);
let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new());
let path1 = self.tcx.item_path_str(def1.did.clone());
let path2 = self.tcx.item_path_str(def2.did.clone());
@ -708,8 +747,19 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
values.0.push_normal(path1);
values.1.push_normal(path2);
// Avoid printing out default generic parameters that are common to both
// types.
let len1 = sub_no_defaults_1.len();
let len2 = sub_no_defaults_2.len();
let common_len = cmp::min(len1, len2);
let remainder1: Vec<_> = sub1.types().skip(common_len).collect();
let remainder2: Vec<_> = sub2.types().skip(common_len).collect();
let common_default_params =
remainder1.iter().rev().zip(remainder2.iter().rev())
.filter(|(a, b)| a == b).count();
let len = sub1.len() - common_default_params;
// Only draw `<...>` if there're lifetime/type arguments.
let len = sub1.len();
if len > 0 {
values.0.push_normal("<");
values.1.push_normal("<");
@ -754,7 +804,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
// ^ elided type as this type argument was the same in both sides
let type_arguments = sub1.types().zip(sub2.types());
let regions_len = sub1.regions().collect::<Vec<_>>().len();
for (i, (ta1, ta2)) in type_arguments.enumerate() {
for (i, (ta1, ta2)) in type_arguments.take(len).enumerate() {
let i = i + regions_len;
if ta1 == ta2 {
values.0.push_normal("_");
@ -784,7 +834,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
&mut values.0,
&mut values.1,
path1.clone(),
sub1,
sub_no_defaults_1,
path2.clone(),
&t2,
).is_some()
@ -796,8 +846,14 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
// Bar<Qux>
// Foo<Bar<Qux>>
// ------- this type argument is exactly the same as the other type
if self.cmp_type_arg(&mut values.1, &mut values.0, path2, sub2, path1, &t1)
.is_some()
if self.cmp_type_arg(
&mut values.1,
&mut values.0,
path2,
sub_no_defaults_2,
path1,
&t1,
).is_some()
{
return values;
}

View File

@ -0,0 +1,86 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
trait Qux {}
struct A;
struct B;
impl Qux for A {}
impl Qux for B {}
struct Foo<T, U: Qux = A, V: Qux = B>(T, U, V);
struct foo;
struct bar;
fn want<T>(t: T) {}
fn have_usize(f: usize) {
want::<foo>(f); //~ ERROR mismatched types
want::<bar>(f); //~ ERROR mismatched types
want::<Foo<usize>>(f); //~ ERROR mismatched types
want::<Foo<usize, B>>(f); //~ ERROR mismatched types
want::<Foo<foo>>(f); //~ ERROR mismatched types
want::<Foo<foo, B>>(f); //~ ERROR mismatched types
want::<Foo<bar>>(f); //~ ERROR mismatched types
want::<Foo<bar, B>>(f); //~ ERROR mismatched types
}
fn have_foo(f: foo) {
want::<usize>(f); //~ ERROR mismatched types
want::<bar>(f); //~ ERROR mismatched types
want::<Foo<usize>>(f); //~ ERROR mismatched types
want::<Foo<usize, B>>(f); //~ ERROR mismatched types
want::<Foo<foo>>(f); //~ ERROR mismatched types
want::<Foo<foo, B>>(f); //~ ERROR mismatched types
want::<Foo<bar>>(f); //~ ERROR mismatched types
want::<Foo<bar, B>>(f); //~ ERROR mismatched types
}
fn have_foo_foo(f: Foo<foo>) {
want::<usize>(f); //~ ERROR mismatched types
want::<foo>(f); //~ ERROR mismatched types
want::<bar>(f); //~ ERROR mismatched types
want::<Foo<usize>>(f); //~ ERROR mismatched types
want::<Foo<usize, B>>(f); //~ ERROR mismatched types
want::<Foo<foo, B>>(f); //~ ERROR mismatched types
want::<Foo<bar>>(f); //~ ERROR mismatched types
want::<Foo<bar, B>>(f); //~ ERROR mismatched types
want::<&Foo<foo>>(f); //~ ERROR mismatched types
want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
}
fn have_foo_foo_b(f: Foo<foo, B>) {
want::<usize>(f); //~ ERROR mismatched types
want::<foo>(f); //~ ERROR mismatched types
want::<bar>(f); //~ ERROR mismatched types
want::<Foo<usize>>(f); //~ ERROR mismatched types
want::<Foo<usize, B>>(f); //~ ERROR mismatched types
want::<Foo<foo>>(f); //~ ERROR mismatched types
want::<Foo<bar>>(f); //~ ERROR mismatched types
want::<Foo<bar, B>>(f); //~ ERROR mismatched types
want::<&Foo<foo>>(f); //~ ERROR mismatched types
want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
}
fn have_foo_foo_b_a(f: Foo<foo, B, A>) {
want::<usize>(f); //~ ERROR mismatched types
want::<foo>(f); //~ ERROR mismatched types
want::<bar>(f); //~ ERROR mismatched types
want::<Foo<usize>>(f); //~ ERROR mismatched types
want::<Foo<usize, B>>(f); //~ ERROR mismatched types
want::<Foo<foo>>(f); //~ ERROR mismatched types
want::<Foo<foo, B>>(f); //~ ERROR mismatched types
want::<Foo<bar>>(f); //~ ERROR mismatched types
want::<Foo<bar, B>>(f); //~ ERROR mismatched types
want::<&Foo<foo>>(f); //~ ERROR mismatched types
want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
}
fn main() {}

View File

@ -0,0 +1,432 @@
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:25:17
|
LL | want::<foo>(f); //~ ERROR mismatched types
| ^ expected struct `foo`, found usize
|
= note: expected type `foo`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:26:17
|
LL | want::<bar>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found usize
|
= note: expected type `bar`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:27:24
|
LL | want::<Foo<usize>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<usize>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:28:27
|
LL | want::<Foo<usize, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<usize, B>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:29:22
|
LL | want::<Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<foo>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:30:25
|
LL | want::<Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<foo, B>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:31:22
|
LL | want::<Foo<bar>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<bar>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:32:25
|
LL | want::<Foo<bar, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found usize
|
= note: expected type `Foo<bar, B>`
found type `usize`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:36:19
|
LL | want::<usize>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `usize`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:37:17
|
LL | want::<bar>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `bar`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:38:24
|
LL | want::<Foo<usize>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<usize>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:39:27
|
LL | want::<Foo<usize, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<usize, B>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:40:22
|
LL | want::<Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<foo>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:41:25
|
LL | want::<Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<foo, B>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:42:22
|
LL | want::<Foo<bar>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<bar>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:43:25
|
LL | want::<Foo<bar, B>>(f); //~ ERROR mismatched types
| ^ expected struct `Foo`, found struct `foo`
|
= note: expected type `Foo<bar, B>`
found type `foo`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:47:19
|
LL | want::<usize>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `Foo`
|
= note: expected type `usize`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:48:17
|
LL | want::<foo>(f); //~ ERROR mismatched types
| ^ expected struct `foo`, found struct `Foo`
|
= note: expected type `foo`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:49:17
|
LL | want::<bar>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `Foo`
|
= note: expected type `bar`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:50:24
|
LL | want::<Foo<usize>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize>`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:51:27
|
LL | want::<Foo<usize, B>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize, B>`
found type `Foo<foo, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:52:25
|
LL | want::<Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected struct `B`, found struct `A`
|
= note: expected type `Foo<_, B>`
found type `Foo<_, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:53:22
|
LL | want::<Foo<bar>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar>`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:54:25
|
LL | want::<Foo<bar, B>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar, B>`
found type `Foo<foo, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:55:23
|
LL | want::<&Foo<foo>>(f); //~ ERROR mismatched types
| ^
| |
| expected &Foo<foo>, found struct `Foo`
| help: consider borrowing here: `&f`
|
= note: expected type `&Foo<foo>`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:56:26
|
LL | want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected reference, found struct `Foo`
|
= note: expected type `&Foo<foo, B>`
found type `Foo<foo>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:60:19
|
LL | want::<usize>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `Foo`
|
= note: expected type `usize`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:61:17
|
LL | want::<foo>(f); //~ ERROR mismatched types
| ^ expected struct `foo`, found struct `Foo`
|
= note: expected type `foo`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:62:17
|
LL | want::<bar>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `Foo`
|
= note: expected type `bar`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:63:24
|
LL | want::<Foo<usize>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize, A>`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:64:27
|
LL | want::<Foo<usize, B>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize, _>`
found type `Foo<foo, _>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:65:22
|
LL | want::<Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected struct `A`, found struct `B`
|
= note: expected type `Foo<_, A>`
found type `Foo<_, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:66:22
|
LL | want::<Foo<bar>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar, A>`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:67:25
|
LL | want::<Foo<bar, B>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar, _>`
found type `Foo<foo, _>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:68:23
|
LL | want::<&Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected &Foo<foo>, found struct `Foo`
|
= note: expected type `&Foo<foo>`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:69:26
|
LL | want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
| ^
| |
| expected reference, found struct `Foo`
| help: consider borrowing here: `&f`
|
= note: expected type `&Foo<foo, B>`
found type `Foo<foo, B>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:73:19
|
LL | want::<usize>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `Foo`
|
= note: expected type `usize`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:74:17
|
LL | want::<foo>(f); //~ ERROR mismatched types
| ^ expected struct `foo`, found struct `Foo`
|
= note: expected type `foo`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:75:17
|
LL | want::<bar>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `Foo`
|
= note: expected type `bar`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:76:24
|
LL | want::<Foo<usize>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize, A, B>`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:77:27
|
LL | want::<Foo<usize, B>>(f); //~ ERROR mismatched types
| ^ expected usize, found struct `foo`
|
= note: expected type `Foo<usize, _, B>`
found type `Foo<foo, _, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:78:22
|
LL | want::<Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected struct `A`, found struct `B`
|
= note: expected type `Foo<_, A, B>`
found type `Foo<_, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:79:25
|
LL | want::<Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected struct `B`, found struct `A`
|
= note: expected type `Foo<_, _, B>`
found type `Foo<_, _, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:80:22
|
LL | want::<Foo<bar>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar, A, B>`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:81:25
|
LL | want::<Foo<bar, B>>(f); //~ ERROR mismatched types
| ^ expected struct `bar`, found struct `foo`
|
= note: expected type `Foo<bar, _, B>`
found type `Foo<foo, _, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:82:23
|
LL | want::<&Foo<foo>>(f); //~ ERROR mismatched types
| ^ expected &Foo<foo>, found struct `Foo`
|
= note: expected type `&Foo<foo>`
found type `Foo<foo, B, A>`
error[E0308]: mismatched types
--> $DIR/type-mismatch.rs:83:26
|
LL | want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
| ^ expected reference, found struct `Foo`
|
= note: expected type `&Foo<foo, B>`
found type `Foo<foo, B, A>`
error: aborting due to 47 previous errors
For more information about this error, try `rustc --explain E0308`.