v3docs: rewrite the documentation of the text and eol attributes

Changes from v2:
- Correct incorrect statement in commit message about dependence of
  `eol` on `text`
- Use "normalize" to refer to conversion to LF, and "convert" for
  conversion from LF
- Add Helped-by line
- Reduce wordiness/redundancy
- Add Junio's suggested phrasing to introduce `eol`

Alex Henrie (1):
  docs: rewrite the documentation of the text and eol attributes

 Documentation/gitattributes.txt | 60 ++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 28 deletions(-)

Range-diff against v2:
1:  446fb632a5 ! 1:  3d5985bc28 docs: rewrite the documentation of the text and eol attributes
    @@ Commit message
         does not do anything to the line endings either.
     
         On top of that, in several places the documentation for the eol
    -    attribute sounds like it can force normalization on checkin and checkout
    -    all by itself, but eol doesn't control normalization on checkin and
    -    doesn't control normalization on checkout either unless accompanied by
    -    the text attribute.
    +    attribute sounds like it can turn on normalization on checkin, but eol
    +    only controls conversion on checkout. It also sounds like setting eol
    +    (or setting a config variable) is required to turn on conversion on
    +    checkout, but the text attribute can turn on conversion on checkout by
    +    itself if eol is unspecified.
     
         Rephrase the documentation of text, text=auto, eol, eol=crlf, and eol=lf
         to be clear about how they are the same, how they are different, and in
    -    what cases normalization is performed.
    +    what cases conversion is performed.
     
    +    Helped-by: Torsten Bögershausen <tboegi@web.de>
         Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
     
      ## Documentation/gitattributes.txt ##
     @@ Documentation/gitattributes.txt: repository upon 'git add' and 'git commit'.
    @@ Documentation/gitattributes.txt: repository upon 'git add' and 'git commit'.
     -`core.eol` (see the definitions of those options in
     -linkgit:git-config[1]).
     +This attribute marks the path as a text file, which enables end-of-line
    -+normalization on checkin and possibly also checkout: When a matching
    -+file is added to the index, even if it has CRLF line endings in the
    -+working directory, the file is stored in the index with LF line endings.
    -+Conversely, when the file is copied from the index to the working
    -+directory, its line endings may be converted from LF to CRLF depending
    -+on the `eol` attribute, the Git config, and the platform (see
    -+explanation of `eol` below).
    ++conversion: When a matching file is added to the index, the file's line
    ++endings are normalized to LF in the index.  Conversely, when the file is
    ++copied from the index to the working directory, its line endings may be
    ++converted from LF to CRLF depending on the `eol` attribute, the Git
    ++config, and the platform (see explanation of `eol` below).
      
      Set::
      
      	Setting the `text` attribute on a path enables end-of-line
     -	normalization and marks the path as a text file.  End-of-line
     -	conversion takes place without guessing the content type.
    -+	normalization on checkin and checkout as described above.  Line
    -+	endings are normalized in the index the next time the file is
    -+	checked in, even if the file was previously added to Git with CRLF
    -+	line endings.
    ++	conversion on checkin and checkout as described above.  Line endings
    ++	are normalized to LF in the index every time the file is checked in,
    ++	even if the file was previously added to Git with CRLF line endings.
      
      Unset::
      
    @@ Documentation/gitattributes.txt: Unset::
      Unspecified::
      
     @@ Documentation/gitattributes.txt: unspecified.
    - This attribute sets a specific line-ending style to be used in the
    - working directory.  This attribute has effect only if the `text`
    - attribute is set or unspecified, or if it is set to `auto`, the file is
    + `eol`
    + ^^^^^
    + 
    +-This attribute sets a specific line-ending style to be used in the
    +-working directory.  This attribute has effect only if the `text`
    +-attribute is set or unspecified, or if it is set to `auto`, the file is
     -detected as text, and it is stored with LF endings in the index.  Note
     -that setting this attribute on paths which are in the index with CRLF
     -line endings may make the paths to be considered dirty unless
     -`text=auto` is set. Adding the path to the index again will normalize
     -the line endings in the index.
    -+detected as text, and it is stored with LF endings in the index.
    ++This attribute marks a path to use a specific line-ending style in the
    ++working tree when it is checked out.  This attribute has effect only if
    ++the `text` attribute is set or unspecified, or if it is set to `auto`,
    ++the file is detected as text, and it is stored with LF endings in the
    ++index.
      
      Set to string value "crlf"::
      
    @@ Documentation/gitattributes.txt: unspecified.
     -	checkin and prevents conversion to CRLF when the file is
     -	checked out.
     +	This setting uses the same line endings in the working directory as
    -+	in the index, whether they are LF or CRLF.  However, unless
    -+	`text=auto`, adding the file to the index again will normalize its
    -+	line endings to LF in the index.
    ++	in the index when the file is checked out.
     +
     +Unspecified::
     +

These two sentences are confusing because the description of the text attribute sounds exactly the same as the description of the text=auto attribute:

"Setting the text attribute on a path enables end-of-line normalization"

"When text is set to "auto", the path is marked for automatic end-of-line conversion"

Unless the reader is already familiar with the two variants, there's a high probability that they will think that "end-of-line normalization" is the same thing as "automatic end-of-line conversion".

It's also not clear that the phrase "When the file has been committed with CRLF, no conversion is done" in the paragraph for text=auto does not apply equally to the bare text attribute which is described earlier. Moreover, it falsely implies that normalization is only suppressed if the file has been committed. In fact, running `git add` on a CRLF file, adding the text=auto attribute to the file, and running `git add` again does not do anything to the line endings either.

On top of that, in several places the documentation for the eol attribute sounds like it can turn on normalization on checkin, but eol only controls conversion on checkout. It also sounds like setting eol (or setting a config variable) is required to turn on conversion on checkout, but the text attribute can turn on conversion on checkout by itself if eol is unspecified.

Rephrase the documentation of text, text=auto, eol, eol=crlf, and eol=lf to be clear about how they are the same, how they are different, and in what cases conversion is performed.

Helped-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
---
 Documentation/gitattributes.txt | 60 ++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 28 deletions(-)

This looks much better, thanks. I have some minor comments: a) The commit message from above:

The word "doc" is used 2 times, that feel a little bit redundant (and should start with a uppercase letter)

"Docs: rewrite the documentation of the text and eol attributes"

Or may be shorter: "Rewrite the documentation of the text and eol attributes"

b) Some more comments inline: On Sun, Apr 30, 2023 at 08:35:33PM -0600, Alex Henrie wrote:

The word "These" is somewhat dangling: Which ones ? May be "The following two sentences" ?

Good.

True.

That's all good.

I still stumble accross "copied". May be shorter:

"the file is written into the working directory"

Good.

It enables even the normalization at checkin, see $ mkdir ttt $ cd ttt $ git init $ echo "*.sh eol=lf" >.gitattributes $ printf '#!/bin/sh\r\necho hello\r\n' >xx.sh $ git add xx.sh warning: CRLF will be replaced by LF in xx.sh. The file will have its original line endings in your working directory

It took me a while to understand it. Should the "," after "unspecified" be removed ?

Or, should we write:

The `eol` attribute automatically sets `text`, unless `-text`, `binary` or `text=auto` is specified.

I dunno.

That's good - I wonder if everyone understands Linux, MacOs and others as Unix.

May be something like this: The default, if `text` is set but neither of those variables, is `eol=crlf` on Windows and `eol=lf` on all other systems.

On Mon, May 1, 2023 at 10:17 PM Torsten Bögershausen <tboegi@web.de> wrote:

The commit message is modeled after 8c591dbfce, which is incidentally the commit that introduced the confusing wording discussed below. Unless there is a convention on how to write commit messages like this, I would rather follow the existing precedent.

The colon indicates that the sentence refers to the following sentences.

Maybe, but then it almost sounds like Git watches the directory for changes and transforms files as soon as the user creates them. Conversion only happens when writing files _from the index_. Moreover, the word "copy" does not always mean a byte-for-byte copy, and clearly does not mean that here.

This has got to be the most confusing Git feature ever. Clearly I did not understand how it works.

Your proposed wording makes the relationship between `text` and `eol` far more clear, and it avoids the need to repeat the detailed explanation of how normalization on checkin works. However, I think we still need to say in the introduction that `eol` does not work without `text`. How about this:

It has effect only if `text` or `text=auto` is set (see above), but specifying `eol` automatically sets `text` if `text` was left unspecified.

I've CCed the author of the original sentence on this email in case he wants to give any feedback on the rewrite.

That's fine, we can say "all other platforms" instead of "Unix" here. It would only become a problem if someone ports Git to DOS, which seems unlikely.

Thanks for the insight and help,

-Alex

Torsten Bögershausen wrote:

This suggestion goes against the Git guideline in SubmittingPatches [1]:

  The title sentence after the "area:" prefix omits the full stop at the
  end, and its first word is not capitalized (the omission of
  capitalization applies only to the word after the "area:" prefix of
  the title) unless there is a reason to capitalize it other than
  because it is the first word in the sentence.  E.g. "doc: clarify...",
  not "doc: Clarify...", or "githooks.txt: improve...", not
  "githooks.txt: Improve...".

If this is touching the documentation, it should have the "docs: " prefix, or "doc: ".

[1] https://git-scm.com/docs/SubmittingPatches

Changes from v3:
- Rewrite sentence about how `eol` can imply `text`
- Use the phrase "all other platforms" instead of the word "Unix"

Alex Henrie (1):
  docs: rewrite the documentation of the text and eol attributes

 Documentation/gitattributes.txt | 59 +++++++++++++++++----------------
 1 file changed, 31 insertions(+), 28 deletions(-)

Range-diff against v3:
1:  3d5985bc28 ! 1:  eccf627db1 docs: rewrite the documentation of the text and eol attributes
    @@ Commit message
         does not do anything to the line endings either.
     
         On top of that, in several places the documentation for the eol
    -    attribute sounds like it can turn on normalization on checkin, but eol
    -    only controls conversion on checkout. It also sounds like setting eol
    +    attribute sounds like either it does not affect normalization on checkin
    +    or it forces normalization on checkin. It also sounds like setting eol
         (or setting a config variable) is required to turn on conversion on
         checkout, but the text attribute can turn on conversion on checkout by
         itself if eol is unspecified.
    @@ Documentation/gitattributes.txt: unspecified.
     -`text=auto` is set. Adding the path to the index again will normalize
     -the line endings in the index.
     +This attribute marks a path to use a specific line-ending style in the
    -+working tree when it is checked out.  This attribute has effect only if
    -+the `text` attribute is set or unspecified, or if it is set to `auto`,
    -+the file is detected as text, and it is stored with LF endings in the
    -+index.
    ++working tree when it is checked out.  It has effect only if `text` or
    ++`text=auto` is set (see above), but specifying `eol` automatically sets
    ++`text` if `text` was left unspecified.
      
      Set to string value "crlf"::
      
    @@ Documentation/gitattributes.txt: unspecified.
     +	If the `eol` attribute is unspecified for a file, its line endings
     +	in the working directory are determined by the `core.autocrlf` or
     +	`core.eol` configuration variable (see the definitions of those
    -+	options in linkgit:git-config[1]).  The default if `text` is set but
    -+	neither of those variables is is `eol=lf` on Unix and `eol=crlf` on
    -+	Windows.
    ++	options in linkgit:git-config[1]).  If `text` is set but neither of
    ++	those variables is, the default is `eol=crlf` on Windows and
    ++	`eol=lf` on all other platforms.
      
      Backwards compatibility with `crlf` attribute
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These two sentences are confusing because the description of the text attribute sounds exactly the same as the description of the text=auto attribute:

"Setting the text attribute on a path enables end-of-line normalization"

"When text is set to "auto", the path is marked for automatic end-of-line conversion"

Unless the reader is already familiar with the two variants, there's a high probability that they will think that "end-of-line normalization" is the same thing as "automatic end-of-line conversion".

It's also not clear that the phrase "When the file has been committed with CRLF, no conversion is done" in the paragraph for text=auto does not apply equally to the bare text attribute which is described earlier. Moreover, it falsely implies that normalization is only suppressed if the file has been committed. In fact, running `git add` on a CRLF file, adding the text=auto attribute to the file, and running `git add` again does not do anything to the line endings either.

On top of that, in several places the documentation for the eol attribute sounds like either it does not affect normalization on checkin or it forces normalization on checkin. It also sounds like setting eol (or setting a config variable) is required to turn on conversion on checkout, but the text attribute can turn on conversion on checkout by itself if eol is unspecified.

Rephrase the documentation of text, text=auto, eol, eol=crlf, and eol=lf to be clear about how they are the same, how they are different, and in what cases conversion is performed.

Helped-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
---
 Documentation/gitattributes.txt | 59 +++++++++++++++++----------------
 1 file changed, 31 insertions(+), 28 deletions(-)

Alex Henrie <alexhenrie24@gmail.com> writes:

Will replace. Unless I hear objections soon, I'll mark it for 'next' and merge it down. Thanks.

On Wed, May 03, 2023 at 09:06:56AM -0700, Junio C Hamano wrote:

That's all fine with me - no objections. Happy line-ending ;-)

Torsten Bögershausen <tboegi@web.de> writes:

Thanks for a quick response. Let me merge it to 'next' on the next integration cycle.