fix: transmute_bytes_to_str wrongly unmangled macros

Author: profetia

clippy_lints/src/transmute/transmute_ref_to_ref.rs

@@ -1,6 +1,6 @@
 use super::{TRANSMUTE_BYTES_TO_STR, TRANSMUTE_PTR_TO_PTR};
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
-use clippy_utils::source::snippet;
+use clippy_utils::source::snippet_with_context;
 use clippy_utils::{std_or_core, sugg};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, Mutability};
@@ -29,7 +29,8 @@ pub(super) fn check<'tcx>(
 
             let postfix = if from_mutbl == Mutability::Mut { "_mut" } else { "" };
 
-            let snippet = snippet(cx, arg.span, "..");
+            let mut applicability = Applicability::MachineApplicable;
+            let (snippet, _) = snippet_with_context(cx, arg.span, e.span.ctxt(), "..", &mut applicability);
 
             span_lint_and_sugg(
                 cx,

tests/ui/transmute.rs

@@ -128,4 +128,17 @@ fn bytes_to_str(mb: &mut [u8]) {
     //~^ transmute_bytes_to_str
 }
 
+fn issue16104() {
+    let b = vec![1_u8, 2_u8];
+    macro_rules! take_ref {
+        ($x:expr) => {
+            $x.as_slice()
+        };
+    }
+    unsafe {
+        let _: &str = std::mem::transmute(take_ref!(b));
+        //~^ transmute_bytes_to_str
+    }
+}
+
 fn main() {}

tests/ui/transmute.stderr

@@ -106,5 +106,11 @@ error: transmute from a `&[u8]` to a `&str`
 LL |     const _: &str = unsafe { std::mem::transmute(B) };
    |                              ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_unchecked(B)`
 
-error: aborting due to 16 previous errors
+error: transmute from a `&[u8]` to a `&str`
+  --> tests/ui/transmute.rs:139:23
+   |
+LL |         let _: &str = std::mem::transmute(take_ref!(b));
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(take_ref!(b)).unwrap()`
+
+error: aborting due to 17 previous errors