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Re: [PATCH v2 07/12] diff: update the way rewrite diff handles incomplete lines

From
Patrick Steinhardt <ps@pks.im>
Date
Nov 10, 2025, 10:06 UTC
Message-ID
<aRG5NSvzeie_J3x9@pks.im>
In-Reply-To
<20251105213052.1499224-8-gitster@pobox.com>
On Wed, Nov 05, 2025 at 01:30:47PM -0800, Junio C Hamano wrote:
Show 5 quoted lines
> The diff_symbol based output framework uses one DIFF_SYMBOL_* enum
> value per the kind of output lines of "git diff", which corresponds
> to one output line from the xdiff machinery used internally.  Most
> notably, DIFF_SYMBOL_PLUS and DIFF_SYMBOL_MINUS that correspond to
> "+" and "-" lines are designed to always take a complete line, even

"complete line" as in newline-terminated? I only recognized that this is what you meant in the next paragraph, so it might be useful to clarify here already what you mean.

Show 44 quoted lines
> diff --git a/diff.c b/diff.c
> index 347cd9c6e9..99298720f4 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -1786,22 +1777,36 @@ static void emit_rewrite_lines(struct emit_callback *ecbdata,
>  	const char *endp = NULL;
>  
>  	while (0 < size) {
> -		int len;
> +		int len, plen;
> +		char *pdata = NULL;
>  
>  		endp = memchr(data, '\n', size);
>  		len = endp ? (endp - data + 1) : size;
> +		plen = len;
> +
> +		if (!endp) {
> +			plen = len + 1;
> +			pdata = xmalloc(plen + 2);
> +			memcpy(pdata, data, len);
> +			pdata[len] = '\n';
> +			pdata[len + 1] = '\0';
> +		}
>  		if (prefix != '+') {
>  			ecbdata->lno_in_preimage++;
> -			emit_del_line(ecbdata, data, len);
> +			emit_del_line(ecbdata, pdata ? pdata : data, plen);
>  		} else {
>  			ecbdata->lno_in_postimage++;
> -			emit_add_line(ecbdata, data, len);
> +			emit_add_line(ecbdata, pdata ? pdata : data, plen);
>  		}
> +		free(pdata);
>  		size -= len;
>  		data += len;
>  	}
> -	if (!endp)
> -		emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_NO_LF_EOF, NULL, 0, 0);
> +	if (!endp) {
> +		static const char nneof[] = "\\ No newline at end of file\n";
> +		ecbdata->last_line_kind = prefix;
> +		emit_incomplete_line(ecbdata, nneof, sizeof(nneof) - 1);
> +	}
>  }

Okay. I was wondering at first how this would get executed for both pre- and postimage if it's not part of the loop anymore. But this is mostly showing my complete ignorance for the "diff" subsystem, as we end up calling `emit_rewrite_lines()` itself once for each image.

Patrick
Previous: Junio C HamanoNext: Junio C Hamano
Message 35 of 73 in “Incomplete lines”
  1. 00/12 Incomplete linesJunio C Hamano, Nov 4, 2025
  2. 01/12 whitespace: correct bit assignment commentsJunio C Hamano, Nov 4, 2025
  3. 02/12 diff: emit_line_ws_markup() if/else style fixJunio C Hamano, Nov 4, 2025
  4. 03/12 diff: correct suppress_blank_empty hackJunio C Hamano, Nov 4, 2025
  5. 04/12 diff: fix incorrect counting of line numbersJunio C Hamano, Nov 4, 2025
  6. Phillip WoodNov 10, 2025
  7. Junio C HamanoNov 10, 2025
  8. Phillip WoodNov 11, 2025
  9. Junio C HamanoNov 11, 2025
  10. 05/12 diff: refactor output of incomplete lineJunio C Hamano, Nov 4, 2025
  11. 06/12 diff: call emit_callback ecbdata everywhereJunio C Hamano, Nov 4, 2025
  12. 07/12 diff: update the way rewrite diff handles incomplete linesJunio C Hamano, Nov 4, 2025
  13. Phillip WoodNov 10, 2025
  14. Junio C HamanoNov 10, 2025
  15. 08/12 apply: revamp the parsing of incomplete linesJunio C Hamano, Nov 4, 2025
  16. 09/12 whitespace: allocate a few more bitsJunio C Hamano, Nov 4, 2025
  17. 10/12 apply: check and fix incomplete linesJunio C Hamano, Nov 4, 2025
  18. 11/12 diff: highlight and error out on incomplete linesJunio C Hamano, Nov 4, 2025
  19. Phillip WoodNov 10, 2025
  20. Junio C HamanoNov 10, 2025
  21. D. Ben KnobleNov 10, 2025
  22. 12/12 attr: enable incomplete-line whitespace error for this projectJunio C Hamano, Nov 4, 2025
  23. Phillip WoodNov 10, 2025
  24. Junio C HamanoNov 10, 2025
  25. 00/12 Incomplete linesJunio C Hamano, Nov 5, 2025
  26. 01/12 whitespace: correct bit assignment commentsJunio C Hamano, Nov 5, 2025
  27. 02/12 diff: emit_line_ws_markup() if/else style fixJunio C Hamano, Nov 5, 2025
  28. 03/12 diff: correct suppress_blank_empty hackJunio C Hamano, Nov 5, 2025
  29. 04/12 diff: fix incorrect counting of line numbersJunio C Hamano, Nov 5, 2025
  30. 05/12 diff: refactor output of incomplete lineJunio C Hamano, Nov 5, 2025
  31. Patrick SteinhardtNov 10, 2025
  32. Junio C HamanoNov 10, 2025
  33. 06/12 diff: call emit_callback ecbdata everywhereJunio C Hamano, Nov 5, 2025
  34. 07/12 diff: update the way rewrite diff handles incomplete linesJunio C Hamano, Nov 5, 2025
  35. Patrick SteinhardtNov 10, 2025
  36. Junio C HamanoNov 10, 2025
  37. 08/12 apply: revamp the parsing of incomplete linesJunio C Hamano, Nov 5, 2025
  38. 09/12 whitespace: allocate a few more bits and define WS_INCOMPLETE_LINEJunio C Hamano, Nov 5, 2025
  39. 10/12 apply: check and fix incomplete linesJunio C Hamano, Nov 5, 2025
  40. 11/12 diff: highlight and error out on incomplete linesJunio C Hamano, Nov 5, 2025
  41. 12/12 attr: enable incomplete-line whitespace error for this projectJunio C Hamano, Nov 5, 2025
  42. Patrick SteinhardtNov 10, 2025
  43. Phillip WoodNov 10, 2025
  44. 00/12 Incomplete linesJunio C Hamano, Nov 11, 2025
  45. 01/12 whitespace: correct bit assignment commentsJunio C Hamano, Nov 11, 2025
  46. 02/12 diff: emit_line_ws_markup() if/else style fixJunio C Hamano, Nov 11, 2025
  47. 03/12 diff: correct suppress_blank_empty hackJunio C Hamano, Nov 11, 2025
  48. 04/12 diff: fix incorrect counting of line numbersJunio C Hamano, Nov 11, 2025
  49. 05/12 diff: refactor output of incomplete lineJunio C Hamano, Nov 11, 2025
  50. 06/12 diff: call emit_callback ecbdata everywhereJunio C Hamano, Nov 11, 2025
  51. 07/12 diff: update the way rewrite diff handles incomplete linesJunio C Hamano, Nov 11, 2025
  52. 08/12 apply: revamp the parsing of incomplete linesJunio C Hamano, Nov 11, 2025
  53. 09/12 whitespace: allocate a few more bits and define WS_INCOMPLETE_LINEJunio C Hamano, Nov 11, 2025
  54. 10/12 apply: check and fix incomplete linesJunio C Hamano, Nov 11, 2025
  55. 11/12 diff: highlight and error out on incomplete linesJunio C Hamano, Nov 11, 2025
  56. 12/12 attr: enable incomplete-line whitespace error for this projectJunio C Hamano, Nov 11, 2025
  57. Phillip WoodNov 11, 2025
  58. 00/12 Incomplete linesJunio C Hamano, Nov 12, 2025
  59. 01/12 whitespace: correct bit assignment commentsJunio C Hamano, Nov 12, 2025
  60. 02/12 diff: emit_line_ws_markup() if/else style fixJunio C Hamano, Nov 12, 2025
  61. 03/12 diff: correct suppress_blank_empty hackJunio C Hamano, Nov 12, 2025
  62. 04/12 diff: keep track of the type of the last line seenJunio C Hamano, Nov 12, 2025
  63. 05/12 diff: refactor output of incomplete lineJunio C Hamano, Nov 12, 2025
  64. 06/12 diff: call emit_callback ecbdata everywhereJunio C Hamano, Nov 12, 2025
  65. 07/12 diff: update the way rewrite diff handles incomplete linesJunio C Hamano, Nov 12, 2025
  66. 08/12 apply: revamp the parsing of incomplete linesJunio C Hamano, Nov 12, 2025
  67. 09/12 whitespace: allocate a few more bits and define WS_INCOMPLETE_LINEJunio C Hamano, Nov 12, 2025
  68. 10/12 apply: check and fix incomplete linesJunio C Hamano, Nov 12, 2025
  69. 11/12 diff: highlight and error out on incomplete linesJunio C Hamano, Nov 12, 2025
  70. 12/12 attr: enable incomplete-line whitespace error for this projectJunio C Hamano, Nov 12, 2025
  71. Phillip WoodNov 14, 2025
  72. Junio C HamanoNov 14, 2025
  73. Junio C HamanoNov 23, 2025

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