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Re: [PATCH] doc: add caveat about roundtripping format-patch

From
PWPhillip Wood <phillip.wood123@gmail.com>
Date
Feb 10, 2026, 10:57 UTC
Message-ID
<7e6a19c0-332c-40dd-8aee-f6dd9324bcfa@gmail.com>
In-Reply-To
<c70adde6-e3db-4a46-bb29-a19d7aba8c7e@app.fastmail.com>
Hi Kristoffer
On 09/02/2026 17:59, Kristoffer Haugsbakk wrote:
Show 22 quoted lines
> Hi Phillip
> On Mon, Feb 9, 2026, at 17:42, Phillip Wood wrote:
>> On 08/02/2026 00:11, kristofferhaugsbakk@fastmail.com wrote:
>>> From: Kristoffer Haugsbakk <code@khaugsbakk.name>
>>>
>>> [snip]
>>> +Patches produced by linkgit:git-format-patch[1] or
>>> +linkgit:git-send-email[1] are inline. This means that the output of
>>> +these two commands can lead to a different commit message when applied
>>> +with linkgit:git-am[1]. It can also mean that the patch is not applied
>>> +correctly.
>>
>> Is this last sentence referring to diffs in the commit message being
>> applied? I don't think there are circumstances where the patch itself is
>> not applied correctly.
> 
> I tested with a line like
> 
>      Index x
> 
> Yesterday and got an empty patch when running git-am(1). But I couldn’t
> reproduce now. I must have made a mistake.

Oh, if you use "Index: x" (with a colon) does that mess up the patch application?

Show 5 quoted lines
> 
> I think this should be changed to:
> 
>      It can also mean that the patch that is applied is not the same as
>      the one that was generated.
That's a nice concise way of putting it
Show 17 quoted lines
> 
> (generated = shorthand for made by git-format-patch(1))
> 
> This sentence would then serve as an introduction for the “Furthermore,”
> paragraph later.
> 
>>> [snip]
>>> +----
>>> +```
>>> +diff ...
>>> +```
>>> +----
>>
>> I'm not sure the markdown really adds anything here
> 
> I don’t understand? It demonstrates a markup for code which does not use
> indentation.

But I think the markup is a distraction from the problem which is that the diff is not indented. Also calling it "Github MarkDown" is unfortunate as we try not to favor one forge over another and many sites support that syntax.

Thanks
Phillip
Show 39 quoted lines
> Well, maybe it should be:
> 
>      ----
>      ```
>      diff ...
>      ...
>      ```
>      ----
> 
> Or maybe...
> 
>      ----
>      ```
>      diff --git a/example.txt b/example.txt
>      ...
>      ```
>      ----
> 
> I’m leaning towards the latter.
> 
>>> [snip]
>>> +One might want to use a general-purpose utility like patch(1) instead,
>>
>> "Given these limitations, one might be tempted to ..."?
> 
> That’s good. That leads with the problem instead letting it trail off at
> the end of the sentence. I’ll use that.
> 
>>> +given these limitations. However, patch(1) will not only look for
>>> +unindented diffs (like linkgit:git-am[1]) but will try to apply indented
>>> +diffs as well.
>>
>> This is useful context.
>>
>> Thanks
>>
>> Phillip
> 
> Thanks for taking a look. It’s always appreciated.
Previous: Kristoffer HaugsbakkNext: Kristoffer Haugsbakk
Message 52 of 65 in “git-am applies commit message diffs”
  1. Matthias BeyerFeb 6, 2026
  2. Jacob KellerFeb 6, 2026
  3. Matthias BeyerFeb 6, 2026
  4. Jeff KingFeb 6, 2026
  5. 0/3 commit-msg.sample: reject messages that would confuse "git am"Phillip Wood, Feb 7, 2026
  6. 1/3 templates: add .gitattributes entry for sample hooksPhillip Wood, Feb 7, 2026
  7. 2/3 templates: detect commit messages containing diffsPhillip Wood, Feb 7, 2026
  8. 3/3 templates: detect messages that contain a separator linePhillip Wood, Feb 7, 2026
  9. Junio C HamanoFeb 7, 2026
  10. Kristoffer HaugsbakkFeb 7, 2026
  11. Junio C HamanoFeb 9, 2026
  12. Jeff KingFeb 9, 2026
  13. Phillip WoodFeb 9, 2026
  14. Jeff KingFeb 10, 2026
  15. Jeff KingFeb 9, 2026
  16. Phillip WoodFeb 9, 2026
  17. Matthias BeyerFeb 9, 2026
  18. Jeff KingFeb 10, 2026
  19. Patrick SteinhardtFeb 9, 2026
  20. Jacob KellerFeb 10, 2026
  21. Patrick SteinhardtFeb 10, 2026
  22. Junio C HamanoFeb 10, 2026
  23. Jacob KellerFeb 11, 2026
  24. Jacob KellerFeb 11, 2026
  25. Jeff KingFeb 11, 2026
  26. Kristoffer HaugsbakkFeb 11, 2026
  27. Junio C HamanoFeb 11, 2026
  28. Jeff KingFeb 10, 2026
  29. 0/2 commit-msg.sample: reject messages that would confuse "git am"Phillip Wood, Feb 13, 2026
  30. 1/2 templates: add .gitattributes entry for sample hooksPhillip Wood, Feb 13, 2026
  31. 2/2 templates: detect commit messages containing diffsPhillip Wood, Feb 13, 2026
  32. Kristoffer HaugsbakkFeb 13, 2026
  33. Junio C HamanoFeb 13, 2026
  34. Phillip WoodFeb 14, 2026
  35. Junio C HamanoFeb 13, 2026
  36. Phillip WoodFeb 14, 2026
  37. Junio C HamanoFeb 14, 2026
  38. Junio C HamanoFeb 13, 2026
  39. Florian WeimerFeb 6, 2026
  40. Jeff KingFeb 6, 2026
  41. Florian WeimerFeb 6, 2026
  42. Jeff KingFeb 6, 2026
  43. Kristoffer HaugsbakkFeb 6, 2026
  44. Jakob HaufeFeb 6, 2026
  45. Kristoffer HaugsbakkFeb 7, 2026
  46. Kristoffer HaugsbakkFeb 7, 2026
  47. doc: add caveat about roundtripping format-patchkristofferhaugsbakk@fastmail.com, Feb 8, 2026
  48. Junio C HamanoFeb 8, 2026
  49. Kristoffer HaugsbakkFeb 8, 2026
  50. Phillip WoodFeb 9, 2026
  51. Kristoffer HaugsbakkFeb 9, 2026
  52. Phillip WoodFeb 10, 2026
  53. Kristoffer HaugsbakkFeb 10, 2026
  54. doc: add caveat about roundtripping format-patchkristofferhaugsbakk@fastmail.com, Feb 9, 2026
  55. Junio C HamanoFeb 9, 2026
  56. Kristoffer HaugsbakkFeb 9, 2026
  57. Phillip WoodFeb 10, 2026
  58. Kristoffer HaugsbakkFeb 10, 2026
  59. doc: add caveat about round-tripping format-patchkristofferhaugsbakk@fastmail.com, Feb 12, 2026
  60. Junio C HamanoFeb 12, 2026
  61. Phillip WoodFeb 13, 2026
  62. Kristoffer HaugsbakkFeb 13, 2026
  63. Junio C HamanoFeb 13, 2026
  64. Christoph Anton MittererFeb 10, 2026
  65. Kristoffer HaugsbakkFeb 10, 2026

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