Fix incorrect type mismatch label pointing at return type

[estebank]

CC #46302.

[rust-highfive]

r? @arielb1

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[arielb1]

This is still wrong in a case such as this:

fnmain(){let x = 0;match x {
_ => {4//~ ERROR}}// (there's a missing semicolon here)println!("hi!");}

I would prefer to have a tag on ExpectHasType unit expectations so we can tell where they come from (missing semicolons, default return type, etc.)

[arielb1]

r? @nikomatsakis

[estebank]

Reopening as although it is imperfect I want to reduce the incidence of incorrect hints.

[nikomatsakis]

Note that this is not strictly true anymore -- maincan return other types!

[nikomatsakis]

@bors r+

[bors]

📌 Commit 6752a5c has been approved by nikomatsakis

[bors]

⌛ Testing commit 6752a5c with merge 184bef4...

[estebank]

@bors retry

[bors]

⌛ Testing commit 6752a5c with merge 73917eb0007c5fce6074abf656bb11e60026fdcc...

[bors]

💔 Test failed - status-appveyor

[kennytm]

Legit, UI test not up-to-date.

---- [ui] ui\suggestions\issue-46302.rs stdout ----
diff of stderr:
2 --> $DIR/issue-46302.rs:13:27
3 |
4	LL | let u: &str = if true { s[..2] } else { s };
- | ^^^^^^ expected &str, found str
+ | ^^^^^^
+ | |
+ | expected &str, found str
+ | help: consider borrowing here: `&s[..2]`
6 |
7 = note: expected type `&str`
8 found type `str`

[estebank]

@kennytm very recent change, updated.

@bors r=nikomatsakis

[bors]

📌 Commit 2636b31 has been approved by nikomatsakis

[bors]

⌛ Testing commit 2636b31 with merge 1029775...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: nikomatsakis
Pushing 1029775 to master...