From 15fc6cfd1ca770891a10ea1eb2ddf2fe05bc2428 Mon Sep 17 00:00:00 2001
From: Linshu Yang <linshuy2@illinois.edu>
Date: Fri, 2 Jan 2026 05:20:23 +0000
Subject: [PATCH] fix: `string_from_utf8_as_bytes` wrongly unmangled macros

---
 clippy_lints/src/strings.rs               |  3 ++-
 tests/ui/string_from_utf8_as_bytes.fixed  | 10 ++++++++++
 tests/ui/string_from_utf8_as_bytes.rs     | 10 ++++++++++
 tests/ui/string_from_utf8_as_bytes.stderr | 10 ++++++++--
 4 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/clippy_lints/src/strings.rs b/clippy_lints/src/strings.rs
index 609504ffc233..c0be724bcdee 100644
--- a/clippy_lints/src/strings.rs
+++ b/clippy_lints/src/strings.rs
@@ -273,6 +273,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
             let string_expression = &expressions[0].0;
 
             let snippet_app = snippet_with_applicability(cx, string_expression.span, "..", &mut applicability);
+            let (right_snip, _) = snippet_with_context(cx, right.span, e.span.ctxt(), "..", &mut applicability);
 
             span_lint_and_sugg(
                 cx,
@@ -280,7 +281,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
                 e.span,
                 "calling a slice of `as_bytes()` with `from_utf8` should be not necessary",
                 "try",
-                format!("Some(&{snippet_app}[{}])", snippet(cx, right.span, "..")),
+                format!("Some(&{snippet_app}[{right_snip}])"),
                 applicability,
             );
         }
diff --git a/tests/ui/string_from_utf8_as_bytes.fixed b/tests/ui/string_from_utf8_as_bytes.fixed
index 193217114d88..98fa3a4fcf70 100644
--- a/tests/ui/string_from_utf8_as_bytes.fixed
+++ b/tests/ui/string_from_utf8_as_bytes.fixed
@@ -1,6 +1,16 @@
 #![warn(clippy::string_from_utf8_as_bytes)]
 
+macro_rules! test_range {
+    ($start:expr, $end:expr) => {
+        $start..$end
+    };
+}
+
 fn main() {
     let _ = Some(&"Hello World!"[6..11]);
     //~^ string_from_utf8_as_bytes
+
+    let s = "Hello World!";
+    let _ = Some(&s[test_range!(6, 11)]);
+    //~^ string_from_utf8_as_bytes
 }
diff --git a/tests/ui/string_from_utf8_as_bytes.rs b/tests/ui/string_from_utf8_as_bytes.rs
index 49beb19ee40f..6354d5376ad6 100644
--- a/tests/ui/string_from_utf8_as_bytes.rs
+++ b/tests/ui/string_from_utf8_as_bytes.rs
@@ -1,6 +1,16 @@
 #![warn(clippy::string_from_utf8_as_bytes)]
 
+macro_rules! test_range {
+    ($start:expr, $end:expr) => {
+        $start..$end
+    };
+}
+
 fn main() {
     let _ = std::str::from_utf8(&"Hello World!".as_bytes()[6..11]);
     //~^ string_from_utf8_as_bytes
+
+    let s = "Hello World!";
+    let _ = std::str::from_utf8(&s.as_bytes()[test_range!(6, 11)]);
+    //~^ string_from_utf8_as_bytes
 }
diff --git a/tests/ui/string_from_utf8_as_bytes.stderr b/tests/ui/string_from_utf8_as_bytes.stderr
index 99c8d8ae4eab..bba9ec0caf19 100644
--- a/tests/ui/string_from_utf8_as_bytes.stderr
+++ b/tests/ui/string_from_utf8_as_bytes.stderr
@@ -1,5 +1,5 @@
 error: calling a slice of `as_bytes()` with `from_utf8` should be not necessary
-  --> tests/ui/string_from_utf8_as_bytes.rs:4:13
+  --> tests/ui/string_from_utf8_as_bytes.rs:10:13
    |
 LL |     let _ = std::str::from_utf8(&"Hello World!".as_bytes()[6..11]);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(&"Hello World!"[6..11])`
@@ -7,5 +7,11 @@ LL |     let _ = std::str::from_utf8(&"Hello World!".as_bytes()[6..11]);
    = note: `-D clippy::string-from-utf8-as-bytes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::string_from_utf8_as_bytes)]`
 
-error: aborting due to 1 previous error
+error: calling a slice of `as_bytes()` with `from_utf8` should be not necessary
+  --> tests/ui/string_from_utf8_as_bytes.rs:14:13
+   |
+LL |     let _ = std::str::from_utf8(&s.as_bytes()[test_range!(6, 11)]);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(&s[test_range!(6, 11)])`
+
+error: aborting due to 2 previous errors