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add lint less_concise_than_option_unwrap_or
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Original file line number | Diff line number | Diff line change |
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use crate::utils; | ||
use if_chain::if_chain; | ||
use rustc_errors::Applicability; | ||
use rustc_hir::{def, Arm, Expr, ExprKind, PatKind, QPath}; | ||
use rustc_lint::{LateContext, LateLintPass}; | ||
use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
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||
declare_clippy_lint! { | ||
/// **What it does:** | ||
/// Finds patterns that can be encoded more concisely with `Option::unwrap_or`. | ||
/// | ||
/// **Why is this bad?** | ||
/// Concise code helps focusing on behavior instead of boilerplate. | ||
/// | ||
/// **Known problems:** None. | ||
/// | ||
/// **Example:** | ||
/// ```rust | ||
/// match int_optional { | ||
/// Some(v) => v, | ||
/// None => 1, | ||
/// } | ||
/// ``` | ||
/// | ||
/// Use instead: | ||
/// ```rust | ||
/// int_optional.unwrap_or(1) | ||
/// ``` | ||
pub LESS_CONCISE_THAN_OPTION_UNWRAP_OR, | ||
pedantic, | ||
"finds patterns that can be encoded more concisely with `Option::unwrap_or`" | ||
} | ||
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declare_lint_pass!(LessConciseThan => [LESS_CONCISE_THAN_OPTION_UNWRAP_OR]); | ||
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impl LateLintPass<'_> for LessConciseThan { | ||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { | ||
if utils::in_macro(expr.span) { | ||
return; | ||
} | ||
if lint_option_unwrap_or_case(cx, expr) { | ||
return; | ||
} | ||
} | ||
} | ||
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||
fn lint_option_unwrap_or_case<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool { | ||
#[allow(clippy::needless_bool)] | ||
fn applicable_none_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> { | ||
if_chain! { | ||
if arms.len() == 2; | ||
if arms.iter().all(|arm| arm.guard.is_none()); | ||
if let Some((idx, none_arm)) = arms.iter().enumerate().find(|(_, arm)| | ||
if_chain! { | ||
if let PatKind::Path(ref qpath) = arm.pat.kind; | ||
if utils::match_qpath(qpath, &utils::paths::OPTION_NONE); | ||
then { true } | ||
else { false } | ||
} | ||
); | ||
let some_arm = &arms[1 - idx]; | ||
if let PatKind::TupleStruct(ref some_qpath, &[some_binding], _) = some_arm.pat.kind; | ||
if utils::match_qpath(some_qpath, &utils::paths::OPTION_SOME); | ||
if let PatKind::Binding(_, binding_hir_id, ..) = some_binding.kind; | ||
if let ExprKind::Path(QPath::Resolved(_, body_path)) = some_arm.body.kind; | ||
if let def::Res::Local(body_path_hir_id) = body_path.res; | ||
if body_path_hir_id == binding_hir_id; | ||
then { Some(none_arm) } | ||
else { None } | ||
} | ||
} | ||
if_chain! { | ||
if !utils::usage::contains_return_break_continue_macro(expr); | ||
if let ExprKind::Match (match_expr, match_arms, _) = expr.kind; | ||
let ty = cx.typeck_results().expr_ty(match_expr); | ||
if utils::is_type_diagnostic_item(cx, ty, sym!(option_type)); | ||
if let Some(none_arm) = applicable_none_arm(match_arms); | ||
if let Some(match_expr_snippet) = utils::snippet_opt(cx, match_expr.span); | ||
if let Some(none_body_snippet) = utils::snippet_opt(cx, none_arm.body.span); | ||
if let Some(indent) = utils::indent_of(cx, expr.span); | ||
then { | ||
let reindented_none_body = | ||
utils::reindent_multiline(none_body_snippet.into(), true, Some(indent)); | ||
let eager_eval = utils::eager_or_lazy::is_eagerness_candidate(cx, none_arm.body); | ||
let method = if eager_eval { | ||
"unwrap_or" | ||
} else { | ||
"unwrap_or_else" | ||
}; | ||
utils::span_lint_and_sugg( | ||
cx, | ||
LESS_CONCISE_THAN_OPTION_UNWRAP_OR, expr.span, | ||
"this pattern can be more concisely encoded with `Option::unwrap_or`", | ||
"replace with", | ||
format!( | ||
"{}.{}({}{})", | ||
match_expr_snippet, | ||
method, | ||
if eager_eval { ""} else { "|| " }, | ||
reindented_none_body | ||
), | ||
Applicability::MachineApplicable, | ||
); | ||
true | ||
} else { false} | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
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// run-rustfix | ||
#![warn(clippy::less_concise_than_option_unwrap_or)] | ||
#![allow(dead_code)] | ||
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fn unwrap_or() { | ||
// int case | ||
Some(1).unwrap_or(42); | ||
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// richer none expr | ||
Some(1).unwrap_or_else(|| 1 + 42); | ||
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// multiline case | ||
Some(1).unwrap_or_else(|| { | ||
let a = 1 + 42; | ||
let b = a + 42; | ||
b + 42 | ||
}); | ||
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// string case | ||
Some("Bob").unwrap_or("Alice"); | ||
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// don't lint | ||
match Some(1) { | ||
Some(i) => i + 2, | ||
None => 42, | ||
}; | ||
match Some(1) { | ||
Some(i) => i, | ||
None => return, | ||
}; | ||
for j in 0..4 { | ||
match Some(j) { | ||
Some(i) => i, | ||
None => continue, | ||
}; | ||
match Some(j) { | ||
Some(i) => i, | ||
None => break, | ||
}; | ||
} | ||
} | ||
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fn main() {} |
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