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Rollup merge of #55423 - zackmdavis:back_out_bogus_ok_wrapping_suggestion, r=estebank 

back out bogus `Ok`-wrapping suggestion on `?` arm type mismatch

This suggestion was introduced in #51938 / 6cc78bf8d7 (while introducing different language for type errors coming from `?` rather than a `match`), but it has a lot of false-positives, and incorrect suggestions carry more badness than marginal good suggestions do goodness. I regret not doing this earlier. 😞

Resolves #52537, resolves #54578.

r? @estebank
This commit is contained in:
Pietro Albini 2018-10-29 09:47:46 +01:00 committed by GitHub
parent 97ff2d6ab1 b7546150b2
commit e5d9da76f2
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4 changed files with 3 additions and 44 deletions
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12
src/librustc/infer/error_reporting/mod.rs
View File

@ -479,17 +479,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
err.span_label(arm_span, msg);
}
}
hir::MatchSource::TryDesugar => {
// Issue #51632
if let Ok(try_snippet) = self.tcx.sess.source_map().span_to_snippet(arm_span) {
err.span_suggestion_with_applicability(
arm_span,
"try wrapping with a success variant",
format!("Ok({})", try_snippet),
Applicability::MachineApplicable,
);
}
}
hir::MatchSource::TryDesugar => {}
_ => {
let msg = "match arm with an incompatible type";
if self.tcx.sess.source_map().is_multiline(arm_span) {

25
src/test/ui/issues/issue-51632-try-desugar-incompatible-types.fixed
View File

@ -1,25 +0,0 @@
// 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.
// run-rustfix
#![allow(dead_code)]
fn missing_discourses() -> Result<isize, ()> {
Ok(1)
}
fn forbidden_narratives() -> Result<isize, ()> {
Ok(missing_discourses()?)
//~^ ERROR try expression alternatives have incompatible types
//~| HELP try wrapping with a success variant
}
fn main() {}

3
src/test/ui/issues/issue-51632-try-desugar-incompatible-types.rs
View File

@ -8,8 +8,6 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// run-rustfix
#![allow(dead_code)]
fn missing_discourses() -> Result<isize, ()> {
@ -19,7 +17,6 @@ fn missing_discourses() -> Result<isize, ()> {
fn forbidden_narratives() -> Result<isize, ()> {
missing_discourses()?
//~^ ERROR try expression alternatives have incompatible types
//~| HELP try wrapping with a success variant
}
fn main() {}

7
src/test/ui/issues/issue-51632-try-desugar-incompatible-types.stderr
View File

@ -1,11 +1,8 @@
error[E0308]: try expression alternatives have incompatible types
--> $DIR/issue-51632-try-desugar-incompatible-types.rs:20:5
--> $DIR/issue-51632-try-desugar-incompatible-types.rs:18:5
|
LL | missing_discourses()?
| ^^^^^^^^^^^^^^^^^^^^^
| |
| expected enum `std::result::Result`, found isize
| help: try wrapping with a success variant: `Ok(missing_discourses()?)`
| ^^^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found isize
|
= note: expected type `std::result::Result<isize, ()>`
found type `isize`