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Suggest let or == on typo'd let-chain

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When encountering a bare assignment in a let-chain, suggest turning the
assignment into a `let` expression or an equality check.

```
error: expected expression, found `let` statement
  --> $DIR/bad-if-let-suggestion.rs:5:8
   |
LL |     if let x = 1 && i = 2 {}
   |        ^^^^^^^^^
   |
   = note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to continue the let-chain
   |
LL |     if let x = 1 && let i = 2 {}
   |                     +++
help: you might have meant to compare for equality
   |
LL |     if let x = 1 && i == 2 {}
   |                        +
```
This commit is contained in:
Esteban Küber 2023-11-22 23:27:15 +00:00
parent aa330518f4
commit 55e4e3e393
6 changed files with 93 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

3
tests/ui/expr/if/bad-if-let-suggestion.rs
View file

@ -1,6 +1,3 @@
// FIXME(compiler-errors): This really should suggest `let` on the RHS of the
// `&&` operator, but that's kinda hard to do because of precedence.
// Instead, for now we just make sure not to suggest `if let let`.
fn a() {
if let x = 1 && i = 2 {}
//~^ ERROR cannot find value `i` in this scope

22
tests/ui/expr/if/bad-if-let-suggestion.stderr
View file

@ -1,19 +1,27 @@
error: expected expression, found `let` statement
--> $DIR/bad-if-let-suggestion.rs:5:8
--> $DIR/bad-if-let-suggestion.rs:2:8
|
LL | if let x = 1 && i = 2 {}
| ^^^^^^^^^
|
= note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to continue the let-chain
|
LL | if let x = 1 && let i = 2 {}
| +++
help: you might have meant to compare for equality
|
LL | if let x = 1 && i == 2 {}
| +
error[E0425]: cannot find value `i` in this scope
--> $DIR/bad-if-let-suggestion.rs:5:21
--> $DIR/bad-if-let-suggestion.rs:2:21
|
LL | if let x = 1 && i = 2 {}
| ^ not found in this scope
error[E0425]: cannot find value `i` in this scope
--> $DIR/bad-if-let-suggestion.rs:12:9
--> $DIR/bad-if-let-suggestion.rs:9:9
|
LL | fn a() {
| ------ similarly named function `a` defined here
@ -22,7 +30,7 @@ LL | if (i + j) = i {}
| ^ help: a function with a similar name exists: `a`
error[E0425]: cannot find value `j` in this scope
--> $DIR/bad-if-let-suggestion.rs:12:13
--> $DIR/bad-if-let-suggestion.rs:9:13
|
LL | fn a() {
| ------ similarly named function `a` defined here
@ -31,7 +39,7 @@ LL | if (i + j) = i {}
| ^ help: a function with a similar name exists: `a`
error[E0425]: cannot find value `i` in this scope
--> $DIR/bad-if-let-suggestion.rs:12:18
--> $DIR/bad-if-let-suggestion.rs:9:18
|
LL | fn a() {
| ------ similarly named function `a` defined here
@ -40,7 +48,7 @@ LL | if (i + j) = i {}
| ^ help: a function with a similar name exists: `a`
error[E0425]: cannot find value `x` in this scope
--> $DIR/bad-if-let-suggestion.rs:19:8
--> $DIR/bad-if-let-suggestion.rs:16:8
|
LL | fn a() {
| ------ similarly named function `a` defined here
@ -49,7 +57,7 @@ LL | if x[0] = 1 {}
| ^ help: a function with a similar name exists: `a`
error[E0308]: mismatched types
--> $DIR/bad-if-let-suggestion.rs:5:8
--> $DIR/bad-if-let-suggestion.rs:2:8
|
LL | if let x = 1 && i = 2 {}
| ^^^^^^^^^^^^^^^^^^ expected `bool`, found `()`

8
tests/ui/rfcs/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.stderr
View file

@ -29,6 +29,10 @@ LL | if let Some(elem) = _opt && [1, 2, 3][let _ = &&let Some(x) = Some(
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to compare for equality
|
LL | if let Some(elem) = _opt && [1, 2, 3][let _ = &&let Some(x) = Some(42)] == 1 {
| +
error: expected expression, found `let` statement
--> $DIR/invalid-let-in-a-valid-let-context.rs:24:23
@ -53,6 +57,10 @@ LL | if let Some(elem) = _opt && [1, 2, 3][let _ = ()] = 1 {
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to compare for equality
|
LL | if let Some(elem) = _opt && [1, 2, 3][let _ = ()] == 1 {
| +
error: expected expression, found `let` statement
--> $DIR/invalid-let-in-a-valid-let-context.rs:42:21