Handle interpolated literal errors

compiler/rustc_parse/src/parser/expr.rs

@@ -2023,17 +2023,14 @@ pub(super) fn parse_opt_meta_item_lit(&mut self) -> Option<MetaItemLit> {
         let recovered = self.recover_after_dot();
         let token = recovered.as_ref().unwrap_or(&self.token);
         match token::Lit::from_token(token) {
-            Some(token_lit) => {
-                match MetaItemLit::from_token_lit(token_lit, token.span) {
+            Some(lit) => {
+                match MetaItemLit::from_token_lit(lit, token.span) {
                     Ok(lit) => {
                         self.bump();
                         Some(lit)
                     }
                     Err(err) => {
-                        let span = token.span;
-                        let token::Literal(lit) = token.kind else {
-                            unreachable!();
-                        };
+                        let span = token.uninterpolated_span();
                         self.bump();
                         report_lit_error(&self.sess, err, lit, span);
                         // Pack possible quotes and prefixes from the original literal into

tests/ui/parser/lit-err-in-macro.rs

@@ -0,0 +1,10 @@
+macro_rules! f {
+    ($abi:literal) => {
+        extern $abi fn f() {}
+    }
+}
+
+f!("Foo"__);
+//~^ ERROR suffixes on string literals are invalid
+
+fn main() {}

tests/ui/parser/lit-err-in-macro.stderr

@@ -0,0 +1,8 @@
+error: suffixes on string literals are invalid
+  --> $DIR/lit-err-in-macro.rs:7:4
+   |
+LL | f!("Foo"__);
+   |    ^^^^^^^ invalid suffix `__`
+
+error: aborting due to previous error
+