zig fmt: fix asm_legacy conversion with quoted identifier

renderSpace takes the length of the original lexeme, so passing the
length of the new lexeme is not correct.

lib/std/zig/Ast/Render.zig

@@ -3673,7 +3673,7 @@ fn tokenSliceForRender(tree: Ast, token_index: Ast.TokenIndex) []const u8 {
     return ret;
 }
 
-fn writeStringLiteralAsIdentifier(r: *Render, token_index: Ast.TokenIndex) !usize {
+fn writeStringLiteralAsIdentifier(r: *Render, token_index: Ast.TokenIndex) Error!usize {
     const tree = r.tree;
     const ais = r.ais;
     assert(tree.tokenTag(token_index) == .string_literal);
@@ -3681,12 +3681,11 @@ fn writeStringLiteralAsIdentifier(r: *Render, token_index: Ast.TokenIndex) !usiz
     const unquoted = lexeme[1..][0 .. lexeme.len - 2];
     if (std.zig.isValidId(unquoted)) {
         try ais.writeAll(unquoted);
-        return unquoted.len;
     } else {
         try ais.writeByte('@');
         try ais.writeAll(lexeme);
-        return lexeme.len + 1;
     }
+    return lexeme.len;
 }
 
 fn hasSameLineComment(tree: Ast, token_index: Ast.TokenIndex) bool {

lib/std/zig/parser_test.zig

@@ -6777,6 +6777,19 @@ test "zig fmt: canonicalize stray backslashes in identifiers" {
     );
 }
 
+test "zig fmt: asm_legacy conversion with quoted identifier" {
+    try testTransform(
+        \\const a = asm (x :: [L] "" (q) : "");
+    ,
+        \\const a = asm (x
+        \\    :
+        \\    : [L] "" (q),
+        \\    : .{ .@"" = true }
+        \\);
+        \\
+    );
+}
+
 test "recovery: top level" {
     try testError(
         \\test "" {inline}