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Rollup merge of #132658 - estebank:const-in-pattern-typo, r=Nadrieril
Detect const in pattern with typo
When writing a constant name incorrectly in a pattern, the pattern will be identified as a new binding. We look for consts in the current crate, consts that where imported in the current crate and for local `let` bindings in case someone got them confused with `const`s.
```
error: unreachable pattern
--> $DIR/const-with-typo-in-pattern-binding.rs:30:9
|
LL | GOOOD => {}
| ----- matches any value
LL |
LL | _ => {}
| ^ no value can reach this
|
help: you might have meant to pattern match against the value of similarly named constant `GOOD` instead of introducing a new catch-all binding
|
LL | GOOD => {}
| ~~~~
```
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,45 @@ | ||
| #![deny(unreachable_patterns)] //~ NOTE the lint level is defined here | ||
| #![allow(non_snake_case, non_upper_case_globals)] | ||
| mod x { | ||
| pub use std::env::consts::ARCH; | ||
| const X: i32 = 0; //~ NOTE there is a constant of the same name | ||
| } | ||
| fn main() { | ||
| let input: i32 = 42; | ||
|
|
||
| const god: i32 = 1; | ||
| const GOOD: i32 = 1; | ||
| const BAD: i32 = 2; | ||
|
|
||
| let name: i32 = 42; //~ NOTE there is a binding of the same name | ||
|
|
||
| match input { | ||
| X => {} //~ NOTE matches any value | ||
| _ => {} //~ ERROR unreachable pattern | ||
| //~^ NOTE no value can reach this | ||
| } | ||
| match input { | ||
| GOD => {} //~ HELP you might have meant to pattern match against the value of similarly named constant `god` | ||
| //~^ NOTE matches any value | ||
| _ => {} //~ ERROR unreachable pattern | ||
| //~^ NOTE no value can reach this | ||
| } | ||
| match input { | ||
| GOOOD => {} //~ HELP you might have meant to pattern match against the value of similarly named constant `GOOD` | ||
| //~^ NOTE matches any value | ||
| _ => {} //~ ERROR unreachable pattern | ||
| //~^ NOTE no value can reach this | ||
| } | ||
| match input { | ||
| name => {} | ||
| //~^ NOTE matches any value | ||
| _ => {} //~ ERROR unreachable pattern | ||
| //~^ NOTE no value can reach this | ||
| } | ||
| match "" { | ||
| ARCH => {} //~ HELP you might have meant to pattern match against the value of constant `ARCH` | ||
| //~^ NOTE matches any value | ||
| _ => {} //~ ERROR unreachable pattern | ||
| //~^ NOTE no value can reach this | ||
| } | ||
| } |
78 changes: 78 additions & 0 deletions
78
tests/ui/resolve/const-with-typo-in-pattern-binding.stderr
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| error: unreachable pattern | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:18:9 | ||
| | | ||
| LL | X => {} | ||
| | - matches any value | ||
| LL | _ => {} | ||
| | ^ no value can reach this | ||
| | | ||
| note: there is a constant of the same name, which could have been used to pattern match against its value instead of introducing a new catch-all binding, but it is not accessible from this scope | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:5:5 | ||
| | | ||
| LL | const X: i32 = 0; | ||
| | ^^^^^^^^^^^^ | ||
| note: the lint level is defined here | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:1:9 | ||
| | | ||
| LL | #![deny(unreachable_patterns)] | ||
| | ^^^^^^^^^^^^^^^^^^^^ | ||
|
|
||
| error: unreachable pattern | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:24:9 | ||
| | | ||
| LL | GOD => {} | ||
| | --- matches any value | ||
| LL | | ||
| LL | _ => {} | ||
| | ^ no value can reach this | ||
| | | ||
| help: you might have meant to pattern match against the value of similarly named constant `god` instead of introducing a new catch-all binding | ||
| | | ||
| LL | god => {} | ||
| | ~~~ | ||
|
|
||
| error: unreachable pattern | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:30:9 | ||
| | | ||
| LL | GOOOD => {} | ||
| | ----- matches any value | ||
| LL | | ||
| LL | _ => {} | ||
| | ^ no value can reach this | ||
| | | ||
| help: you might have meant to pattern match against the value of similarly named constant `GOOD` instead of introducing a new catch-all binding | ||
| | | ||
| LL | GOOD => {} | ||
| | ~~~~ | ||
|
|
||
| error: unreachable pattern | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:36:9 | ||
| | | ||
| LL | name => {} | ||
| | ---- matches any value | ||
| LL | | ||
| LL | _ => {} | ||
| | ^ no value can reach this | ||
| | | ||
| note: there is a binding of the same name; if you meant to pattern match against the value of that binding, that is a feature of constants that is not available for `let` bindings | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:14:9 | ||
| | | ||
| LL | let name: i32 = 42; | ||
| | ^^^^ | ||
|
|
||
| error: unreachable pattern | ||
| --> $DIR/const-with-typo-in-pattern-binding.rs:42:9 | ||
| | | ||
| LL | ARCH => {} | ||
| | ---- matches any value | ||
| LL | | ||
| LL | _ => {} | ||
| | ^ no value can reach this | ||
| | | ||
| help: you might have meant to pattern match against the value of constant `ARCH` instead of introducing a new catch-all binding | ||
| | | ||
| LL | std::env::consts::ARCH => {} | ||
| | ~~~~~~~~~~~~~~~~~~~~~~ | ||
|
|
||
| error: aborting due to 5 previous errors | ||
|
|