proc_macro: Add Literal::c_string constructor

Author: novafacing

library/proc_macro/src/lib.rs

@@ -45,6 +45,7 @@ mod diagnostic;
 #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
 pub use diagnostic::{Diagnostic, Level, MultiSpan};
 
+use std::ffi::CStr;
 use std::ops::{Range, RangeBounds};
 use std::path::PathBuf;
 use std::str::FromStr;
@@ -1351,6 +1352,15 @@ impl Literal {
         Literal::new(bridge::LitKind::ByteStr, &string, None)
     }
 
+    /// C string literal.
+    #[stable(feature = "c_str_literals", since = "1.76.0")]
+    pub fn c_string(string: &CStr) -> Literal {
+        let quoted = format!("{:?}", string);
+        assert!(quoted.starts_with('"') && quoted.ends_with('"'));
+        let symbol = &quoted[1..quoted.len() - 1];
+        Literal::new(bridge::LitKind::CStr, symbol, None)
+    }
+
     /// Returns the span encompassing this literal.
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn span(&self) -> Span {

tests/ui/feature-gates/feature-gate-proc_macro_c_string.rs

@@ -0,0 +1,10 @@
+// force-host
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+use proc_macro::Literal;
+
+fn test() {
+    Literal::c_string(c"a"); //~ ERROR use of unstable library feature 'c_str_literals'
+}

tests/ui/proc-macro/auxiliary/api/mod.rs

@@ -5,6 +5,7 @@
 #![crate_name = "proc_macro_api_tests"]
 #![feature(proc_macro_span)]
 #![feature(proc_macro_byte_character)]
+#![feature(c_str_literals)]
 #![deny(dead_code)] // catch if a test function is never called
 
 extern crate proc_macro;

tests/ui/proc-macro/auxiliary/api/parse.rs

@@ -23,6 +23,10 @@ fn test_display_literal() {
         Literal::string("a \t ❤ ' \" \u{1}").to_string(),
         "\"a \\t ❤ ' \\\" \\u{1}\"",
     );
+    assert_eq!(
+        Literal::c_string(c"a \t ❤ ' \" \u{1}").to_string(),
+        "\"a \\t ❤ ' \\\" \\u{1}\"",
+    );
     assert_eq!(Literal::character('a').to_string(), "'a'");
     assert_eq!(Literal::character('\t').to_string(), "'\\t'");
     assert_eq!(Literal::character('❤').to_string(), "'❤'");
@@ -41,6 +45,7 @@ fn test_parse_literal() {
     assert_eq!("b'a'".parse::<Literal>().unwrap().to_string(), "b'a'");
     assert_eq!("\"\n\"".parse::<Literal>().unwrap().to_string(), "\"\n\"");
     assert_eq!("b\"\"".parse::<Literal>().unwrap().to_string(), "b\"\"");
+    assert_eq!("c\"\"".parse::<Literal>().unwrap().to_string(), "c\"\"");
     assert_eq!("r##\"\"##".parse::<Literal>().unwrap().to_string(), "r##\"\"##");
     assert_eq!("10ulong".parse::<Literal>().unwrap().to_string(), "10ulong");
     assert_eq!("-10ulong".parse::<Literal>().unwrap().to_string(), "-10ulong");