[gcc/devel/rust/master] libproc_macro: Implement Display for LexError

[gcc/devel/rust/master] libproc_macro: Implement Display for LexError

[Thomas Schwinge]

https://gcc.gnu.org/g:b74ef5aca042ea3f89c5b5eedd027dac9a457425

commit b74ef5aca042ea3f89c5b5eedd027dac9a457425
Author: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date:   Mon Feb 20 13:40:03 2023 +0100

    libproc_macro: Implement Display for LexError
    
    Implement the Display trait for LexError by writing an error string to
    the the output formatter.
    
    ChangeLog:
    
            * librust/proc_macro/rust/lib.rs: Implement Display for
            LexError.
    
    Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Diff:
---
 librust/proc_macro/rust/lib.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/librust/proc_macro/rust/lib.rs b/librust/proc_macro/rust/lib.rs
index 31676f15199..13f66f04fac 100644
--- a/librust/proc_macro/rust/lib.rs
+++ b/librust/proc_macro/rust/lib.rs
@@ -124,8 +124,8 @@ impl From<Literal> for TokenTree {
 pub struct LexError;
 
 impl fmt::Display for LexError {
-    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        todo!("Implement this function")
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("cannot parse string into token stream")
     }
 }