format macro argument parsing fix

compiler/rustc_parse_format/src/lib.rs

@@ -213,11 +213,13 @@ impl<'a> Iterator for Parser<'a> {
                         Some(String(self.string(pos + 1)))
                     } else {
                         let arg = self.argument();
-                        if let Some(end) = self.must_consume('}') {
-                            let start = self.to_span_index(pos);
-                            let end = self.to_span_index(end + 1);
+                        if let Some(rbrace_byte_idx) = self.must_consume('}') {
+                            let lbrace_inner_offset = self.to_span_index(pos);
+                            let rbrace_inner_offset = self.to_span_index(rbrace_byte_idx);
                             if self.is_literal {
-                                self.arg_places.push(start.to(end));
+                                self.arg_places.push(
+                                    lbrace_inner_offset.to(InnerOffset(rbrace_inner_offset.0 + 1)),
+                                );
                             }
                         }
                         Some(NextArgument(arg))

src/test/ui/macros/issue-83344.rs

@@ -0,0 +1,6 @@
+// check-fail
+
+fn main() {
+    println!("{}\
+"); //~^ ERROR: 1 positional argument in format string, but no arguments were given
+}

src/test/ui/macros/issue-83344.stderr

@@ -0,0 +1,8 @@
+error: 1 positional argument in format string, but no arguments were given
+  --> $DIR/issue-83344.rs:4:15
+   |
+LL |     println!("{}\
+   |               ^^
+
+error: aborting due to previous error
+

src/tools/clippy/tests/ui/write_literal_2.stderr

@@ -75,8 +75,9 @@ LL |         "1", "2", "3",
    |
 help: try this
    |
-LL |         "some 1{} / {}", "2", "3",
-   |               ^        --
+LL |         "some 1/
+LL |         {} / {}", "2", "3",
+   |
 
 error: literal with an empty format string
   --> $DIR/write_literal_2.rs:25:14