fix: incorrect error message for string literal suffixes

compiler/rustc_parse/src/parser/expr.rs

@@ -1561,7 +1561,31 @@ impl<'a> Parser<'a> {
     fn parse_expr_lit(&mut self) -> PResult<'a, Box<Expr>> {
         let lo = self.token.span;
         match self.parse_opt_token_lit() {
-            Some((token_lit, _)) => {
+            Some((token_lit, span)) => {
+                // For raw string literals with suffixes, report the error immediately
+                // This helps provide better error messages for cases like r#"..."#suffix
+                if token_lit.suffix.is_some()
+                    && matches!(token_lit.kind, token::StrRaw(_))
+                    && ast::LitKind::from_token_lit(token_lit).is_err()
+                {
+                    if let Err(err) = ast::LitKind::from_token_lit(token_lit) {
+                        let guar = report_lit_error(&self.psess, err, token_lit, span);
+                        let token_lit = token::Lit::new(token::Err(guar), token_lit.symbol, None);
+                        let expr =
+                            self.mk_expr(lo.to(self.prev_token.span), ExprKind::Lit(token_lit));
+
+                        // Consume the next token if it looks like another string literal
+                        // This prevents cascading errors when raw strings with invalid suffixes
+                        // are immediately followed by another string
+                        if let TokenKind::Literal(lit) = &self.token.kind {
+                            if matches!(lit.kind, token::LitKind::Str | token::LitKind::StrRaw(_)) {
+                                self.bump();
+                            }
+                        }
+
+                        return self.maybe_recover_from_bad_qpath(expr);
+                    }
+                }
                 let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Lit(token_lit));
                 self.maybe_recover_from_bad_qpath(expr)
             }

tests/ui/parser/bad-lit-suffixes.stderr

@@ -10,6 +10,12 @@ error: suffixes on string literals are invalid
 LL |     "C"suffix
    |     ^^^^^^^^^ invalid suffix `suffix`
 
+error: suffixes on string literals are invalid
+  --> $DIR/bad-lit-suffixes.rs:14:5
+   |
+LL |     r#""#suffix;
+   |     ^^^^^^^^^^^ invalid suffix `suffix`
+
 error: suffixes on string literals are invalid
   --> $DIR/bad-lit-suffixes.rs:30:17
    |
@@ -62,12 +68,6 @@ error: suffixes on byte string literals are invalid
 LL |     b""suffix;
    |     ^^^^^^^^^ invalid suffix `suffix`
 
-error: suffixes on string literals are invalid
-  --> $DIR/bad-lit-suffixes.rs:14:5
-   |
-LL |     r#""#suffix;
-   |     ^^^^^^^^^^^ invalid suffix `suffix`
-
 error: suffixes on byte string literals are invalid
   --> $DIR/bad-lit-suffixes.rs:15:5
    |

tests/ui/parser/raw-string-suffix-invalid.rs

@@ -0,0 +1,7 @@
+// Test for issue #144161: Wrong error for string literal suffix when stuck together
+// This tests the case where a raw string has an invalid suffix immediately followed by another string
+
+fn main() {
+    let s = r#" \\ "#r"\\ ";
+    //~^ ERROR suffixes on string literals are invalid
+}

tests/ui/parser/raw-string-suffix-invalid.stderr

@@ -0,0 +1,8 @@
+error: suffixes on string literals are invalid
+  --> $DIR/raw-string-suffix-invalid.rs:5:13
+   |
+LL |     let s = r#" \ "#r"\ ";
+   |             ^^^^^^^^^^ invalid suffix `r`
+
+error: aborting due to 1 previous error
+

tests/ui/parser/raw-string-suffix-long.rs

@@ -0,0 +1,7 @@
+// Test for raw string literals with invalid suffixes
+
+fn main() {
+    // Raw string literal with hash delimiters and suffix
+    let s2 = r##"test"##suffix;
+    //~^ ERROR suffixes on string literals are invalid
+}

tests/ui/parser/raw-string-suffix-long.stderr

@@ -0,0 +1,8 @@
+error: suffixes on string literals are invalid
+  --> $DIR/raw-string-suffix-long.rs:5:14
+   |
+LL |     let s2 = r##"test"##suffix;
+   |              ^^^^^^^^^^^^^^^^^ invalid suffix `suffix`
+
+error: aborting due to 1 previous error
+

tests/ui/parser/raw-string-suffix-word.rs

@@ -0,0 +1,7 @@
+// Test for raw string literal with word suffix
+
+fn main() {
+    // Raw string literal with word suffix
+    let s3 = r#"test"#invalid;
+    //~^ ERROR suffixes on string literals are invalid
+}

tests/ui/parser/raw-string-suffix-word.stderr

@@ -0,0 +1,8 @@
+error: suffixes on string literals are invalid
+  --> $DIR/raw-string-suffix-word.rs:5:14
+   |
+LL |     let s3 = r#"test"#invalid;
+   |              ^^^^^^^^^^^^^^^^ invalid suffix `invalid`
+
+error: aborting due to 1 previous error
+