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

Trevor Gross
2023-10-08T09:56:20Z

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@gmail.com>
Signed-off-by: Trevor Gross <tmgross@umich.edu>
---

Original mention of this problem in [1]

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

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