Add c'…' idea.

text/3348-c-str-literal.md

@@ -95,7 +95,12 @@ Interactions with string related macros:
 # Unresolved questions
 [unresolved-questions]: #unresolved-questions
 
+- Also add `c'…'` as [`c_char`](https://doc.rust-lang.org/stable/core/ffi/type.c_char.html) literal?
+
+  It'd be identical to `b'…'`, except it'd be a `c_char` (`i8`) instead of `u8`.
+
 - Should we make `&CStr` a thin pointer before stabilizing this? (If so, how?)
+
 - Should the (unstable) [`concat_bytes` macro](https://github.com/rust-lang/rust/issues/87555) accept C string literals? (If so, should it evaluate to a C string or byte string?)
 
 # Future possibilities