Fix sliced_string_as_bytes FP with a RangeFull

Author: yotamofek

clippy_lints/src/methods/sliced_string_as_bytes.rs

@@ -1,15 +1,21 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::higher;
 use clippy_utils::res::MaybeDef;
 use clippy_utils::source::snippet_with_applicability;
 use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, LangItem, is_range_literal};
+use rustc_hir::{Expr, ExprKind, LangItem};
 use rustc_lint::LateContext;
 
 use super::SLICED_STRING_AS_BYTES;
 
+/// Checks if `index` is any type of range except `RangeFull` (i.e. `..`)
+fn is_bounded_range_literal(cx: &LateContext<'_>, index: &Expr<'_>) -> bool {
+    higher::Range::hir(cx, index).is_some_and(|range| Option::or(range.start, range.end).is_some())
+}
+
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>) {
     if let ExprKind::Index(indexed, index, _) = recv.kind
-        && is_range_literal(index)
+        && is_bounded_range_literal(cx, index)
         && let ty = cx.typeck_results().expr_ty(indexed).peel_refs()
         && (ty.is_str() || ty.is_lang_item(cx, LangItem::String))
     {

tests/ui/sliced_string_as_bytes.fixed

@@ -32,6 +32,12 @@ fn main() {
     let bytes = &"consectetur adipiscing".as_bytes()[..=5];
     //~^ sliced_string_as_bytes
 
+    // this lint is a perf lint meant to catch utf-8 alignment checks.
+    // while the slicing here *is* redundant, it's more like a needless borrow, and shouldn't affect
+    // perf
+    let bytes = s[..].as_bytes();
+    let bytes = string[..].as_bytes();
+
     let f = Foo;
     let bytes = f[0..4].as_bytes();
 }

tests/ui/sliced_string_as_bytes.rs

@@ -32,6 +32,12 @@ fn main() {
     let bytes = "consectetur adipiscing"[..=5].as_bytes();
     //~^ sliced_string_as_bytes
 
+    // this lint is a perf lint meant to catch utf-8 alignment checks.
+    // while the slicing here *is* redundant, it's more like a needless borrow, and shouldn't affect
+    // perf
+    let bytes = s[..].as_bytes();
+    let bytes = string[..].as_bytes();
+
     let f = Foo;
     let bytes = f[0..4].as_bytes();
 }