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[PATCH v4 1/3] add -p: detect more mismatches between plain vs colored diffs

From
Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date
Aug 31, 2022, 20:31 UTC
Message-ID
<25187c3a3c2bb440ab0af34011db41361d4e2496.1661977877.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.1336.v4.git.1661977877.gitgitgadget@gmail.com>
From: Johannes Schindelin <johannes.schindelin@gmx.de>

When parsing the colored version of a diff, the interactive `add` command really relies on the colored version having the same number of lines as the plain (uncolored) version. That is an invariant.

We already have code to verify correctly when the colored diff has less lines than the plain diff. Modulo an off-by-one bug: If the last diff line has no matching colored one, the code pretends to succeed, still.

To make matters worse, when we adjusted the test in 1e4ffc765db (t3701: adjust difffilter test, 2020-01-14), we did not catch this because `add -p` fails for a _different_ reason: it does not find any colored hunk header that contains a parseable line range.

If we change the test case so that the line range _can_ be parsed, the bug is exposed.

Let's address all of the above by
- fixing the off-by-one,
- adjusting the test case to allow `add -p` to parse the line range
- making the test case more stringent by verifying that the expected
  error message is shown
Also adjust a misleading code comment about the now-fixed code.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 add-patch.c                | 5 ++++-
 t/t3701-add-interactive.sh | 5 +++--
 2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/add-patch.c b/add-patch.c
index 509ca04456b..34f3807ff32 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -592,7 +592,10 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 			if (colored_eol)
 				colored_p = colored_eol + 1;
 			else if (p != pend)
-				/* colored shorter than non-colored? */
+				/* non-colored has more lines? */
+				goto mismatched_output;
+			else if (colored_p == colored_pend)
+				/* last line has no matching colored one? */
 				goto mismatched_output;
 			else
 				colored_p = colored_pend;
diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index 3b7df9bed5a..8a594700f7b 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -761,9 +761,10 @@ test_expect_success 'detect bogus diffFilter output' '
 	git reset --hard &&
 
 	echo content >test &&
-	test_config interactive.diffFilter "sed 1d" &&
+	test_config interactive.diffFilter "sed 6d" &&
 	printf y >y &&
-	force_color test_must_fail git add -p <y
+	force_color test_must_fail git add -p <y >output 2>&1 &&
+	grep "mismatched output" output
 '
 
 test_expect_success 'handle very large filtered diff' '
-- 
gitgitgadget
Previous: Johannes SchindelinNext: Phillip Wood
Message 56 of 67 in “built-in add -p: support diff-so-fancy better”
  1. 0/3 built-in add -p: support diff-so-fancy betterJohannes Schindelin via GitGitGadget, Aug 23, 2022
  2. 3/3 add -p: handle `diff-so-fancy`'s hunk headers betterJohannes Schindelin via GitGitGadget, Aug 23, 2022
  3. 1/3 t3701: redefine what is "bogus" output of a diff filterJohannes Schindelin via GitGitGadget, Aug 23, 2022
  4. 2/3 add -p: gracefully ignore unparseable hunk headers in colored diffsJohannes Schindelin via GitGitGadget, Aug 23, 2022
  5. Philippe BlainAug 24, 2022
  6. Johannes SchindelinAug 24, 2022
  7. Philippe BlainAug 24, 2022
  8. Philippe BlainAug 24, 2022
  9. Junio C HamanoAug 24, 2022
  10. Johannes SchindelinAug 24, 2022
  11. Junio C HamanoAug 24, 2022
  12. 0/4 built-in add -p: support diff-so-fancy betterJohannes Schindelin via GitGitGadget, Aug 24, 2022
  13. 1/4 t3701: redefine what is "bogus" output of a diff filterJohannes Schindelin via GitGitGadget, Aug 24, 2022
  14. 2/4 add -p: gracefully ignore unparseable hunk headers in colored diffsJohannes Schindelin via GitGitGadget, Aug 24, 2022
  15. Junio C HamanoAug 29, 2022
  16. 3/4 add -p: handle `diff-so-fancy`'s hunk headers betterJohannes Schindelin via GitGitGadget, Aug 24, 2022
  17. Junio C HamanoAug 29, 2022
  18. Johannes SchindelinAug 29, 2022
  19. Junio C HamanoAug 29, 2022
  20. Johannes SchindelinAug 30, 2022
  21. 4/4 add -p: ignore dirty submodulesJohannes Schindelin via GitGitGadget, Aug 24, 2022
  22. Junio C HamanoAug 24, 2022
  23. Philippe BlainAug 25, 2022
  24. Johannes SchindelinAug 26, 2022
  25. Philippe BlainAug 26, 2022
  26. 0/5 built-in add -p: support diff-so-fancy betterJohannes Schindelin via GitGitGadget, Aug 29, 2022
  27. 1/5 t3701: redefine what is "bogus" output of a diff filterJohannes Schindelin via GitGitGadget, Aug 29, 2022
  28. Phillip WoodAug 30, 2022
  29. Junio C HamanoAug 30, 2022
  30. Phillip WoodAug 31, 2022
  31. Jeff KingAug 31, 2022
  32. Jeff KingAug 31, 2022
  33. Johannes SchindelinAug 31, 2022
  34. 2/5 add -p: gracefully ignore unparseable hunk headers in colored diffsJohannes Schindelin via GitGitGadget, Aug 29, 2022
  35. 4/5 add -p: handle `diff-so-fancy`'s hunk headers betterJohannes Schindelin via GitGitGadget, Aug 29, 2022
  36. Phillip WoodAug 30, 2022
  37. 3/5 add -p: insert space in colored hunk header as neededJohannes Schindelin via GitGitGadget, Aug 29, 2022
  38. 5/5 add -p: ignore dirty submodulesJohannes Schindelin via GitGitGadget, Aug 29, 2022
  39. Phillip WoodAug 30, 2022
  40. Johannes SchindelinAug 31, 2022
  41. Junio C HamanoAug 31, 2022
  42. Johannes SchindelinAug 31, 2022
  43. Junio C HamanoAug 29, 2022
  44. Johannes SchindelinAug 30, 2022
  45. Phillip WoodAug 30, 2022
  46. Johannes SchindelinAug 31, 2022
  47. 0/3 built-in add -p: support diff-so-fancy betterJohannes Schindelin via GitGitGadget, Aug 31, 2022
  48. 2/3 add -p: gracefully handle unparseable hunk headers in colored diffsJohannes Schindelin via GitGitGadget, Aug 31, 2022
  49. Phillip WoodSep 1, 2022
  50. Johannes SchindelinSep 1, 2022
  51. 3/3 add -p: ignore dirty submodulesJohannes Schindelin via GitGitGadget, Aug 31, 2022
  52. Jeff KingSep 1, 2022
  53. Jeff KingSep 1, 2022
  54. Junio C HamanoSep 1, 2022
  55. Johannes SchindelinSep 2, 2022
  56. 1/3 add -p: detect more mismatches between plain vs colored diffsJohannes Schindelin via GitGitGadget, Aug 31, 2022
  57. Phillip WoodSep 1, 2022
  58. Phillip WoodSep 1, 2022
  59. Junio C HamanoSep 1, 2022
  60. 0/3 built-in add -p: support diff-so-fancy betterJohannes Schindelin via GitGitGadget, Sep 1, 2022
  61. 1/3 add -p: detect more mismatches between plain vs colored diffsJohannes Schindelin via GitGitGadget, Sep 1, 2022
  62. 3/3 add -p: ignore dirty submodulesJohannes Schindelin via GitGitGadget, Sep 1, 2022
  63. Junio C HamanoSep 1, 2022
  64. 2/3 add -p: gracefully handle unparseable hunk headers in colored diffsJohannes Schindelin via GitGitGadget, Sep 1, 2022
  65. Phillip WoodSep 1, 2022
  66. Phillip WoodSep 1, 2022
  67. Junio C HamanoSep 1, 2022

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