From 2389830deaf39b736e35c471e39543d30f708972 Mon Sep 17 00:00:00 2001
From: Esteban Küber <esteban@kuber.com.ar>
Date: Fri, 17 Feb 2017 14:31:59 -0800
Subject: Highlight and simplify mismatched types

Shorten mismatched types errors by replacing subtypes that are not
different with `_`, and highlighting only the subtypes that are
different.

Given a file

```rust
struct X<T1, T2> {
    x: T1,
    y: T2,
}

fn foo() -> X<X<String, String>, String> {
    X { x: X {x: "".to_string(), y: 2}, y: "".to_string()}
}

fn bar() -> Option<String> {
    "".to_string()
}
```

provide the following output

```rust
error[E0308]: mismatched types
  --> file.rs:6:5
   |
 6 |     X { x: X {x: "".to_string(), y: 2}, y: "".to_string()}
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `std::string::String`, found {integer}
   |
   = note: expected type `X<X<_, std::string::String>, _>`
                                 ^^^^^^^^^^^^^^^^^^^   // < highlighted
              found type `X<X<_, {integer}>, _>`
                                 ^^^^^^^^^             // < highlighted

error[E0308]: mismatched types
  --> file.rs:6:5
   |
10 |     "".to_string()
   |     ^^^^^^^^^^^^^^ expected struct `std::option::Option`, found `std::string::String`
   |
   = note: expected type `Option<std::string::String>`
                          ^^^^^^^                   ^  // < highlighted
              found type `std::string::String`
```
---
 src/librustc_errors/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/librustc_errors/lib.rs')

diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index 2efdaa57fba..da29e354a70 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -203,7 +203,7 @@ impl error::Error for ExplicitBug {
     }
 }
 
-pub use diagnostic::{Diagnostic, SubDiagnostic};
+pub use diagnostic::{Diagnostic, SubDiagnostic, DiagnosticStyledString, StringPart};
 pub use diagnostic_builder::DiagnosticBuilder;
 
 /// A handler deals with errors; certain errors
-- 
cgit 1.4.1-3-g733a5