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Auto merge of #9289 - mkrasnitski:9094, r=xFrednet

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Extend `if_then_some_else_none` to also suggest `bool::then_some`

Closes #9094.

changelog: Extend `if_then_some_else_none` to also suggest `bool::then_some`
This commit is contained in:
bors 2022-08-12 06:25:59 +00:00
commit 05fc1c7dbc
2 changed files with 52 additions and 46 deletions
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90
clippy_lints/src/if_then_some_else_none.rs
View file

@ -1,7 +1,7 @@
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::eager_or_lazy::switch_to_eager_eval;
use clippy_utils::source::snippet_with_macro_callsite;
use clippy_utils::{contains_return, higher, is_else_clause, is_lang_ctor, meets_msrv, msrvs, peel_blocks};
use if_chain::if_chain;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{Expr, ExprKind, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
@ -11,10 +11,12 @@ use rustc_session::{declare_tool_lint, impl_lint_pass};
declare_clippy_lint! {
/// ### What it does
/// Checks for if-else that could be written to `bool::then`.
/// Checks for if-else that could be written using either `bool::then` or `bool::then_some`.
///
/// ### Why is this bad?
/// Looks a little redundant. Using `bool::then` helps it have less lines of code.
/// Looks a little redundant. Using `bool::then` is more concise and incurs no loss of clarity.
/// For simple calculations and known values, use `bool::then_some`, which is eagerly evaluated
/// in comparison to `bool::then`.
///
/// ### Example
/// ```rust
@ -39,7 +41,7 @@ declare_clippy_lint! {
#[clippy::version = "1.53.0"]
pub IF_THEN_SOME_ELSE_NONE,
restriction,
"Finds if-else that could be written using `bool::then`"
"Finds if-else that could be written using either `bool::then` or `bool::then_some`"
}
pub struct IfThenSomeElseNone {
@ -56,7 +58,7 @@ impl IfThenSomeElseNone {
impl_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
if !meets_msrv(self.msrv, msrvs::BOOL_THEN) {
return;
}
@ -70,43 +72,47 @@ impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
return;
}
if_chain! {
if let Some(higher::If { cond, then, r#else: Some(els) }) = higher::If::hir(expr);
if let ExprKind::Block(then_block, _) = then.kind;
if let Some(then_expr) = then_block.expr;
if let ExprKind::Call(then_call, [then_arg]) = then_expr.kind;
if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
if is_lang_ctor(cx, then_call_qpath, OptionSome);
if let ExprKind::Path(ref qpath) = peel_blocks(els).kind;
if is_lang_ctor(cx, qpath, OptionNone);
if !stmts_contains_early_return(then_block.stmts);
then {
let cond_snip = snippet_with_macro_callsite(cx, cond.span, "[condition]");
let cond_snip = if matches!(cond.kind, ExprKind::Unary(_, _) | ExprKind::Binary(_, _, _)) {
format!("({})", cond_snip)
} else {
cond_snip.into_owned()
};
let arg_snip = snippet_with_macro_callsite(cx, then_arg.span, "");
let closure_body = if then_block.stmts.is_empty() {
arg_snip.into_owned()
} else {
format!("{{ /* snippet */ {} }}", arg_snip)
};
let help = format!(
"consider using `bool::then` like: `{}.then(|| {})`",
cond_snip,
closure_body,
);
span_lint_and_help(
cx,
IF_THEN_SOME_ELSE_NONE,
expr.span,
"this could be simplified with `bool::then`",
None,
&help,
);
}
if let Some(higher::If { cond, then, r#else: Some(els) }) = higher::If::hir(expr)
&& let ExprKind::Block(then_block, _) = then.kind
&& let Some(then_expr) = then_block.expr
&& let ExprKind::Call(then_call, [then_arg]) = then_expr.kind
&& let ExprKind::Path(ref then_call_qpath) = then_call.kind
&& is_lang_ctor(cx, then_call_qpath, OptionSome)
&& let ExprKind::Path(ref qpath) = peel_blocks(els).kind
&& is_lang_ctor(cx, qpath, OptionNone)
&& !stmts_contains_early_return(then_block.stmts)
{
let cond_snip = snippet_with_macro_callsite(cx, cond.span, "[condition]");
let cond_snip = if matches!(cond.kind, ExprKind::Unary(_, _) | ExprKind::Binary(_, _, _)) {
format!("({})", cond_snip)
} else {
cond_snip.into_owned()
};
let arg_snip = snippet_with_macro_callsite(cx, then_arg.span, "");
let mut method_body = if then_block.stmts.is_empty() {
arg_snip.into_owned()
} else {
format!("{{ /* snippet */ {} }}", arg_snip)
};
let method_name = if switch_to_eager_eval(cx, expr) && meets_msrv(self.msrv, msrvs::BOOL_THEN_SOME) {
"then_some"
} else {
method_body.insert_str(0, "|| ");
"then"
};
let help = format!(
"consider using `bool::{}` like: `{}.{}({})`",
method_name, cond_snip, method_name, method_body,
);
span_lint_and_help(
cx,
IF_THEN_SOME_ELSE_NONE,
expr.span,
&format!("this could be simplified with `bool::{}`", method_name),
None,
&help,
);
}
}

8
tests/ui/if_then_some_else_none.stderr
View file

@ -27,21 +27,21 @@ LL | | };
|
= help: consider using `bool::then` like: `matches!(true, true).then(|| { /* snippet */ matches!(true, false) })`
error: this could be simplified with `bool::then`
error: this could be simplified with `bool::then_some`
--> $DIR/if_then_some_else_none.rs:23:28
|
LL | let _ = x.and_then(|o| if o < 32 { Some(o) } else { None });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using `bool::then` like: `(o < 32).then(|| o)`
= help: consider using `bool::then_some` like: `(o < 32).then_some(o)`
error: this could be simplified with `bool::then`
error: this could be simplified with `bool::then_some`
--> $DIR/if_then_some_else_none.rs:27:13
|
LL | let _ = if !x { Some(0) } else { None };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using `bool::then` like: `(!x).then(|| 0)`
= help: consider using `bool::then_some` like: `(!x).then_some(0)`
error: this could be simplified with `bool::then`
--> $DIR/if_then_some_else_none.rs:82:13