[Bug]: %% escape prints two percent signs when no format argument remains

[leo-aa88]

Description

The %% escape (a literal percent sign) is only collapsed to a single % when there is still an unconsumed format argument. When the format string has no remaining arguments — e.g. yapping("100%%"), or any %% that appears after all arguments have been consumed — both percent characters are emitted literally, so the output contains %% instead of %. This affects yapping, yappin, baka, and yapto (they share the formatter / the same code shape).

Minimal reproduction code

skibidi main {
    yapping("100%%");
    yapping("with arg %d and %%", 5);
    bussin 0;
}

Expected behavior

100%
with arg 5 and %

(As in C printf, %% always prints a single %.)

Actual behavior

$ ./brainrot pct.brainrot
100%%
with arg 5 and %%

Note the second line: after %d consumes the only argument, the trailing %% is also emitted literally.

Brainrot version / commit

19b9563

Operating system

Ubuntu on WSL2 (Linux 5.15)

Additional context

Root cause: stdrot/yapping.c (stdrot_format_to_stream) and identically stdrot/baka.c. The %% handling lives inside the branch guarded by if (*format == '%' && arg_idx < arg_count):

if (*format == '%' && arg_idx < arg_count)
{
    ...
    if (*format == '%') { buffer[buffer_offset++] = '%'; format++; continue; }
    ...
}
else
{
    buffer[buffer_offset++] = *format++;   // copies each '%' literally
}

When arg_idx >= arg_count, a % (including the first % of a %%) falls to the else branch and is copied verbatim, so %% survives as two characters. The %% escape should be recognized regardless of whether arguments remain — it consumes no argument.

[OkiriGabriel]

I'd like to take this issue. Could a maintainer assign it to me?

I'll open a linked PR once assigned.