[PATCH] rust: macros: update 'paste!' macro to accept string literals

[Trevor Gross]

Enable combining identifiers with string literals in the 'paste!' macro.
This allows combining user-specified strings with affixes to create
namespaced identifiers.

This sample code:

    macro_rules! m {
        ($name:lit) => {
            paste!(struct [<_some_ $name _struct_>];)
        }
    }

    m!("foo_bar");

Would previously cause a compilation error. It will now generate:

    struct _some_foo_bar_struct_;

Reported-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
Signed-off-by: Trevor Gross <tmgross@xxxxxxxxx>
---

Original mention of this problem in [1]

[1]: https://lore.kernel.org/rust-for-linux/20231008.164906.1151622782836568538.fujita.tomonori@xxxxxxxxx/

 rust/macros/paste.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/rust/macros/paste.rs b/rust/macros/paste.rs
index 385a78434224..f40d42b35b58 100644
--- a/rust/macros/paste.rs
+++ b/rust/macros/paste.rs
@@ -9,7 +9,15 @@ fn concat(tokens: &[TokenTree], group_span: Span) -> TokenTree {
     loop {
         match tokens.next() {
             None => break,
-            Some(TokenTree::Literal(lit)) => segments.push((lit.to_string(), lit.span())),
+            Some(TokenTree::Literal(lit)) => {
+                // Allow us to concat string literals by stripping quotes
+                let mut value = lit.to_string();
+                if value.starts_with('"') && value.ends_with('"') {
+                    value.remove(0);
+                    value.pop();
+                }
+                segments.push((value, lit.span()));
+            }
             Some(TokenTree::Ident(ident)) => {
                 let mut value = ident.to_string();
                 if value.starts_with("r#") {
-- 
2.34.1