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[redundant_guards]: lint empty string checks

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This commit is contained in:
y21 2023-11-15 19:33:30 +01:00
parent abf01e469b
commit ef587d22a4
1 changed files with 40 additions and 13 deletions
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53
clippy_lints/src/matches/redundant_guards.rs
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@ -1,6 +1,6 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::path_to_local;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::source::snippet;
use clippy_utils::visitors::{for_each_expr, is_local_used};
use rustc_ast::{BorrowKind, LitKind};
use rustc_errors::Applicability;
@ -9,6 +9,7 @@
use rustc_lint::LateContext;
use rustc_span::symbol::Ident;
use rustc_span::Span;
use std::borrow::Cow;
use std::ops::ControlFlow;
use super::REDUNDANT_GUARDS;
@ -41,7 +42,14 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
(PatKind::Ref(..), None) | (_, Some(_)) => continue,
_ => arm.pat.span,
};
emit_redundant_guards(cx, outer_arm, if_expr.span, pat_span, &binding, arm.guard);
emit_redundant_guards(
cx,
outer_arm,
if_expr.span,
snippet(cx, pat_span, "<binding>"),
&binding,
arm.guard,
);
}
// `Some(x) if let Some(2) = x`
else if let Guard::IfLet(let_expr) = guard
@ -52,7 +60,14 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
(PatKind::Ref(..), None) | (_, Some(_)) => continue,
_ => let_expr.pat.span,
};
emit_redundant_guards(cx, outer_arm, let_expr.span, pat_span, &binding, None);
emit_redundant_guards(
cx,
outer_arm,
let_expr.span,
snippet(cx, pat_span, "<binding>"),
&binding,
None,
);
}
// `Some(x) if x == Some(2)`
// `Some(x) if Some(2) == x`
@ -78,7 +93,25 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
(ExprKind::AddrOf(..), None) | (_, Some(_)) => continue,
_ => pat.span,
};
emit_redundant_guards(cx, outer_arm, if_expr.span, pat_span, &binding, None);
emit_redundant_guards(
cx,
outer_arm,
if_expr.span,
snippet(cx, pat_span, "<binding>"),
&binding,
None,
);
} else if let Guard::If(if_expr) = guard
&& let ExprKind::MethodCall(path, recv, ..) = if_expr.kind
&& let Some(binding) = get_pat_binding(cx, recv, outer_arm)
{
let ty = cx.typeck_results().expr_ty(recv).peel_refs();
if path.ident.name == sym!(is_empty) && ty.is_str() {
// `s if s.is_empty()` becomes ""
emit_redundant_guards(cx, outer_arm, if_expr.span, r#""""#.into(), &binding, None)
}
}
}
}
@ -134,19 +167,16 @@ fn emit_redundant_guards<'tcx>(
cx: &LateContext<'tcx>,
outer_arm: &Arm<'tcx>,
guard_span: Span,
pat_span: Span,
binding_replacement: Cow<'static, str>,
pat_binding: &PatBindingInfo,
inner_guard: Option<Guard<'_>>,
) {
let mut app = Applicability::MaybeIncorrect;
span_lint_and_then(
cx,
REDUNDANT_GUARDS,
guard_span.source_callsite(),
"redundant guard",
|diag| {
let binding_replacement = snippet_with_applicability(cx, pat_span, "<binding_repl>", &mut app);
let suggestion_span = match *pat_binding {
PatBindingInfo {
span,
@ -170,14 +200,11 @@ fn emit_redundant_guards<'tcx>(
Guard::IfLet(l) => ("if let", l.span),
};
format!(
" {prefix} {}",
snippet_with_applicability(cx, span, "<guard>", &mut app),
)
format!(" {prefix} {}", snippet(cx, span, "<guard>"))
}),
),
],
app,
Applicability::MaybeIncorrect,
);
},
);