f0e586c251
Unlike past similar work done in #6228, expand the existing `or_fun_call` lint to detect `or_insert` calls with a `T::new()` or `T::default()` argument, much like currently done for `unwrap_or` calls. In that case, suggest the use of `or_default`, which is more idiomatic. Note that even with this change, `or_insert_with(T::default)` calls aren't detected as candidates for `or_default()`, in the same manner that currently `unwrap_or_else(T::default)` calls aren't detected as candidates for `unwrap_or_default()`. Also, as a nearby cleanup, change `KNOW_TYPES` from `static` to `const`, since as far as I understand it's preferred (should Clippy have a lint for that?). Fixes #3812.
27 lines
No EOL
637 B
Text
27 lines
No EOL
637 B
Text
### What it does
|
|
Checks for calls to `.or(foo(..))`, `.unwrap_or(foo(..))`,
|
|
`.or_insert(foo(..))` etc., and suggests to use `.or_else(|| foo(..))`,
|
|
`.unwrap_or_else(|| foo(..))`, `.unwrap_or_default()` or `.or_default()`
|
|
etc. instead.
|
|
|
|
### Why is this bad?
|
|
The function will always be called and potentially
|
|
allocate an object acting as the default.
|
|
|
|
### Known problems
|
|
If the function has side-effects, not calling it will
|
|
change the semantic of the program, but you shouldn't rely on that anyway.
|
|
|
|
### Example
|
|
```
|
|
foo.unwrap_or(String::new());
|
|
```
|
|
|
|
Use instead:
|
|
```
|
|
foo.unwrap_or_else(String::new);
|
|
|
|
// or
|
|
|
|
foo.unwrap_or_default();
|
|
``` |