Re: [PATCH] Fortran: Fix FMT_X/TR output into already-written content, [PR114618]

Disregard this effort, I am back to doing things the old fashioned way

On 6/14/26 10:05 PM, Jerry D wrote:
> See attached patch which cleans up I hope the last of the tabbing issues in 
> formatted output.  I renamed the existing test case and created a new one to 
> test several variations.
> 
> Comments appreciated.
> 
> Regression tested on X86_64.
> 
> Ok for mainline? No plans to backport unless someone thinks its needed.
> 
> Best regards,
> 
> Jerry
> 
> ---
> 
> When an X or TR edit descriptor advances the file position into
> content that has already been written (e.g. after a backward T or
> TL tab), formatted_transfer_scalar_write either corrupted the
> pending_spaces accounting or overwrote the existing characters with
> blanks.
> 
> Fix this by detecting the case where pending_spaces is negative and
> skips is positive (the advance falls within already-written content)
> and using write_x (skips, 0) to move the file position forward
> without overwriting.  Also, for stream I/O, compute bytes_used from
> fbuf->pos (the current write position) rather than fbuf->act (the
> high-water mark), since the two diverge after a backward tab followed
> by a partial overwrite, which previously prevented this case from
> being detected for stream units.
> 
> Assisted by: Claude Sonnet 4.6
> 
>      PR libfortran/114618
> 
> libgfortran/ChangeLog:
> 
>      * io/transfer.c (formatted_transfer_scalar_write): Use
>      fbuf->pos rather than fbuf->act for bytes_used with stream
>      I/O.  When pending_spaces is negative and skips is positive,
>      advance the position with write_x (skips, 0) instead of
>      overwriting existing content.
> 
> gcc/testsuite/ChangeLog:
> 
>      * gfortran.dg/pr114618.f90: Move to...
>      * gfortran.dg/fmt_t_10.f90: ...here.
>      * gfortran.dg/fmt_t_11.f90: New test.
> ---