git diff bug?

Please see
http://github.com/techarcana/elisp/commit/63d672c296316c85690085930b05c642b88a9978#diff-2

Note how the @@ ... @@ clauses are followed by text from the previous
line's comment.  Not sure, but this strikes me as a line-ending issue.
custom.el was originally built on a linux machine; now I'm using a Mac.

Thanks!

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com

On Fri, Apr 03, 2009 at 09:10:42PM -0400, David Abrahams wrote:

Please see
http://github.com/techarcana/elisp/commit/63d672c296316c85690085930b05c642b88a9978#diff-2

Note how the @@ ... @@ clauses are followed by text from the previous
line's comment.  Not sure, but this strikes me as a line-ending issue.
custom.el was originally built on a linux machine; now I'm using a Mac.

This is as designed. The original file ("git show e7dd7db") contains (my
numbering seems different than what git produces; it is produced by "nl"
which is maybe treating some line endings differently earlier in the
file):

   102   '(mm-attachment-override-types (quote ("text/x-vcard" "application/pkcs7-mime" "application/x-pkcs7-mime" "application/pkcs7-signature" "application/x-pkcs7-signature" "image/*")) nil nil "
   103  Added image/* to display attached images inline")
   104   '(mm-discouraged-alternatives (quote ("text/html" "text/richtext" "image/.*")) nil nil "
   105  The documentation for this variable says it all")
   106   '(mm-inline-text-html-with-images t)
   107   '(muse-project-alist (quote (("WikiPlanner" ("~/plans" :default "index" :major-mode planner-mode :visit-link planner-visit-link)))))
   108   '(org-agenda-files (quote ("~/organizer.org")))

The changed text in your diff starts on 108. So we show 105-107 as
context lines. The text after the @@ clause is the "function header";
this is equivalent to "-p" in GNU diff. It's basically a guess about the
most interesting context to show, and looks alphabetic characters that
are left-aligned. In the case of lisp, it really isn't all that
interesting (and what looks so weird is that your file contains
a lot of

  "\nSome text"

so the text strings are all left-aligned. You can customize the regex
used to guess at the function header. See "defining a custom
hunk-header" in "git help attributes".

-Peff

On Fri, Apr 03, 2009 at 09:45:27PM -0400, Jeff King wrote:

This is as designed. The original file ("git show e7dd7db") contains (my
numbering seems different than what git produces; it is produced by "nl"
which is maybe treating some line endings differently earlier in the
file):

Sorry, this was just me failing to use "nl" correctly. I needed to use
"-ba" to number empty lines. So the line numbers do match git, and the
rest of my explanation holds.

-Peff

On Apr 3, 2009, at 9:45 PM, Jeff King wrote:

On Fri, Apr 03, 2009 at 09:10:42PM -0400, David Abrahams wrote:

quoted

Please see
http://github.com/techarcana/elisp/commit/63d672c296316c85690085930b05c642b88a9978#diff-2

Note how the @@ ... @@ clauses are followed by text from the previous
line's comment.  Not sure, but this strikes me as a line-ending issue.
custom.el was originally built on a linux machine; now I'm using a Mac.

This is as designed. The original file ("git show e7dd7db") contains (my
numbering seems different than what git produces; it is produced by "nl"
which is maybe treating some line endings differently earlier in the
file):

  102   '(mm-attachment-override-types (quote ("text/x-vcard" "application/pkcs7-mime" "application/x-pkcs7-mime" "application/pkcs7-signature" "application/x-pkcs7-signature" "image/*")) nil nil "
  103  Added image/* to display attached images inline")
  104   '(mm-discouraged-alternatives (quote ("text/html" "text/richtext" "image/.*")) nil nil "
  105  The documentation for this variable says it all")
  106   '(mm-inline-text-html-with-images t)
  107   '(muse-project-alist (quote (("WikiPlanner" ("~/plans" :default "index" :major-mode planner-mode :visit-link planner-visit-link)))))
  108   '(org-agenda-files (quote ("~/organizer.org")))

The changed text in your diff starts on 108. So we show 105-107 as
context lines. The text after the @@ clause is the "function header";
this is equivalent to "-p" in GNU diff. It's basically a guess about the
most interesting context to show, and looks alphabetic characters that
are left-aligned. In the case of lisp, it really isn't all that
interesting (and what looks so weird is that your file contains
a lot of

 "\nSome text"

so the text strings are all left-aligned. You can customize the regex
used to guess at the function header. See "defining a custom
hunk-header" in "git help attributes".

Hmm, so I tried sticking this .gitattributes in my repo

  *.el   diff=el
  [diff "el"]
        xfuncname = "^(\\(def[a-z]+ .+)$"

and git diff barfed with

  "el"] is not a valid attribute name: .gitattributes:2
  "^(\\(def[a-z]+ is not a valid attribute name: .gitattributes:3

What am I missing?  I tried googling, but from what turns up for me, it doesn't look like anyone else has ever tried to use this feature!

TIA,

--
David Abrahams
BoostPro Computing
http://boostpro.com

David Abrahams venit, vidit, dixit 06.04.2009 11:09:

On Apr 3, 2009, at 9:45 PM, Jeff King wrote:

quoted

On Fri, Apr 03, 2009 at 09:10:42PM -0400, David Abrahams wrote:

quoted

Please see
http://github.com/techarcana/elisp/commit/63d672c296316c85690085930b05c642b88a9978#diff-2

Note how the @@ ... @@ clauses are followed by text from the previous
line's comment.  Not sure, but this strikes me as a line-ending  
issue.
custom.el was originally built on a linux machine; now I'm using a  
Mac.

This is as designed. The original file ("git show e7dd7db") contains  
(my
numbering seems different than what git produces; it is produced by  
"nl"
which is maybe treating some line endings differently earlier in the
file):

  102   '(mm-attachment-override-types (quote ("text/x-vcard"  
"application/pkcs7-mime" "application/x-pkcs7-mime" "application/ 
pkcs7-signature" "application/x-pkcs7-signature" "image/*")) nil nil "
  103  Added image/* to display attached images inline")
  104   '(mm-discouraged-alternatives (quote ("text/html" "text/ 
richtext" "image/.*")) nil nil "
  105  The documentation for this variable says it all")
  106   '(mm-inline-text-html-with-images t)
  107   '(muse-project-alist (quote (("WikiPlanner" ("~/ 
plans" :default "index" :major-mode planner-mode :visit-link planner- 
visit-link)))))
  108   '(org-agenda-files (quote ("~/organizer.org")))

The changed text in your diff starts on 108. So we show 105-107 as
context lines. The text after the @@ clause is the "function header";
this is equivalent to "-p" in GNU diff. It's basically a guess about  
the
most interesting context to show, and looks alphabetic characters that
are left-aligned. In the case of lisp, it really isn't all that
interesting (and what looks so weird is that your file contains
a lot of

 "\nSome text"

so the text strings are all left-aligned. You can customize the regex
used to guess at the function header. See "defining a custom
hunk-header" in "git help attributes".

Hmm, so I tried sticking this .gitattributes in my repo

   *.el   diff=el
   [diff "el"]
         xfuncname = "^(\\(def[a-z]+ .+)$"

and git diff barfed with

   "el"] is not a valid attribute name: .gitattributes:2
   "^(\\(def[a-z]+ is not a valid attribute name: .gitattributes:3

What am I missing?  I tried googling, but from what turns up for me,  
it doesn't look like anyone else has ever tried to use this feature!

Well, I don't think anayone else has tried putting config lines into
.gitattributes ;)

The "*.el" line goes into .gitattributes (or .git/info/a...), the other
lines are config lines and thus goe into .git/config or .gitconfig.

Michael

On Mon, Apr 06, 2009 at 05:09:32AM -0400, David Abrahams wrote:

Hmm, so I tried sticking this .gitattributes in my repo

  *.el   diff=el
  [diff "el"]
        xfuncname = "^(\\(def[a-z]+ .+)$"

and git diff barfed with

As Michael explained, the first line goes into .gitattributes, and the
second two go into your .git/config.

The reason is that the first line is describing a property of files
in the repo: "*.el is of type 'el' for diffing". And thus it makes sense
for it to be committed along with the content in the repo.

But the latter two lines are about preference: "here is how _I_ would
like to generate diffs for el files". So they go in your personal config
which is not shipped with the repo. And most likely you would want to
put them not in per-repo config, but in your user config:
$HOME/.gitconfig.

All of that being said, it is obviously a documentation failure if it
didn't explain in which files the various parts go. If you don't mind,
can you skim over the documentation you read one more time and point out
where it led you wrong?  Maybe we can make it a little clearer.

-Peff

On Apr 6, 2009, at 10:44 AM, Michael J Gruber wrote:

Well, I don't think anayone else has tried putting config lines into
.gitattributes ;)

The "*.el" line goes into .gitattributes (or .git/info/a...), the other
lines are config lines and thus goe into .git/config or .gitconfig.

Aha, thanks.  The hunk header section in the gitattributes manpage turns out to be the only one that shows config stuff without mentioning a config file, thus my confusion.  I suggest a tiny patch ('cept I don't know how to write manpage format)

--
David Abrahams
BoostPro Computing
http://boostpro.com

On Apr 6, 2009, at 11:53 AM, Jeff King wrote:

All of that being said, it is obviously a documentation failure if it
didn't explain in which files the various parts go. If you don't mind,
can you skim over the documentation you read one more time and point out
where it led you wrong?  Maybe we can make it a little clearer.

Wow, that is a *really* admirable response.  Git itself may be a tad arcane, but the community has been fantastic. Thanks billionses for that -- it can only mean more a more learnable Git down the road.  I posted an answer to your question in a different reply.

--
David Abrahams
BoostPro Computing
http://boostpro.com

On Mon, Apr 06, 2009 at 01:58:08PM -0400, David Abrahams wrote:

quoted

The "*.el" line goes into .gitattributes (or .git/info/a...), the other
lines are config lines and thus goe into .git/config or .gitconfig.

Aha, thanks.  The hunk header section in the gitattributes manpage turns 
out to be the only one that shows config stuff without mentioning a config 
file, thus my confusion.  I suggest a tiny patch ('cept I don't know how 
to write manpage format)

Neither do I, but fortunately the git docs are all written in asciidoc. :)

Junio, does the patch below make sense to you?

-- >8 --
Subject: [PATCH] doc/gitattributes: clarify location of config text

The gitattributes documentation has a section on the "diff"
attribute, with subsections for each of the things you might
want to configure in your diff config section (external
diff, hunk headers, etc). The first such subsection
specifically notes that the definition of the diff driver
should go into $GIT_DIR/config, but subsequent sections do
not.

This location is implied if you are reading the
documentation sequentially, but it is not uncommon for a new
user to jump to (or be referred to) a specific section. For
a new user who does not know git well enough to recognize
the config syntax, it is not clear that those directives
don't also go into the gitattributes file.

This patch just mentions the config file in each subsection,
similar to the way it is mentioned in the first.

Signed-off-by: Jeff King <redacted>
---
Mentioning $GIT_DIR/config _and_ $HOME/.gitconfig in each subsection may
seem like overkill, but I really think we shouldn't make any assumption
that a reader has seen the previous sections. They otherwise stand alone
very well.

I arrived at these three sections by grepping for '^[' to find example
config file syntax.

 Documentation/gitattributes.txt |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 55668e3..b6260b1 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt

@@ -297,7 +297,8 @@ for paths.
 
 Then, you would define a "diff.tex.xfuncname" configuration to
 specify a regular expression that matches a line that you would
-want to appear as the hunk header "TEXT", like this:
+want to appear as the hunk header "TEXT". Add a section to your
+`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 
 ------------------------
 [diff "tex"]

@@ -345,7 +346,8 @@ split words in a line, by specifying an appropriate regular expression
 in the "diff.*.wordRegex" configuration variable.  For example, in TeX
 a backslash followed by a sequence of letters forms a command, but
 several such commands can be run together without intervening
-whitespace.  To separate them, use a regular expression such as
+whitespace.  To separate them, use a regular expression in your
+`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 
 ------------------------
 [diff "tex"]

@@ -373,7 +375,8 @@ resulting text on stdout.
 
 For example, to show the diff of the exif information of a
 file instead of the binary information (assuming you have the
-exif tool installed):
+exif tool installed), add the following section to your
+`$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
 
 ------------------------
 [diff "jpg"]

-- 
1.6.2.2.585.g1e067

I believe you need to have only the line

*.el diff=el

in the .gitattributes file.

The part

[diff = "el"]
   xfuncname = ...

has to be in the git config file. The .git/config file would do for this.


On Mon, Apr 6, 2009 at 2:39 PM, David Abrahams [off-list ref] wrote:

On Apr 3, 2009, at 9:45 PM, Jeff King wrote:

quoted

On Fri, Apr 03, 2009 at 09:10:42PM -0400, David Abrahams wrote:

quoted

Please see
http://github.com/techarcana/elisp/commit/63d672c296316c85690085930b05c642b88a9978#diff-2

Note how the @@ ... @@ clauses are followed by text from the previous
line's comment.  Not sure, but this strikes me as a line-ending issue.
custom.el was originally built on a linux machine; now I'm using a Mac.

This is as designed. The original file ("git show e7dd7db") contains (my
numbering seems different than what git produces; it is produced by "nl"
which is maybe treating some line endings differently earlier in the
file):

 102   '(mm-attachment-override-types (quote ("text/x-vcard" "application/pkcs7-mime" "application/x-pkcs7-mime" "application/pkcs7-signature" "application/x-pkcs7-signature" "image/*")) nil nil "
 103  Added image/* to display attached images inline")
 104   '(mm-discouraged-alternatives (quote ("text/html" "text/richtext" "image/.*")) nil nil "
 105  The documentation for this variable says it all")
 106   '(mm-inline-text-html-with-images t)
 107   '(muse-project-alist (quote (("WikiPlanner" ("~/plans" :default "index" :major-mode planner-mode :visit-link planner-visit-link)))))
 108   '(org-agenda-files (quote ("~/organizer.org")))

The changed text in your diff starts on 108. So we show 105-107 as
context lines. The text after the @@ clause is the "function header";
this is equivalent to "-p" in GNU diff. It's basically a guess about the
most interesting context to show, and looks alphabetic characters that
are left-aligned. In the case of lisp, it really isn't all that
interesting (and what looks so weird is that your file contains
a lot of

 "\nSome text"

so the text strings are all left-aligned. You can customize the regex
used to guess at the function header. See "defining a custom
hunk-header" in "git help attributes".

Hmm, so I tried sticking this .gitattributes in my repo

 *.el   diff=el
 [diff "el"]
       xfuncname = "^(\\(def[a-z]+ .+)$"

and git diff barfed with

 "el"] is not a valid attribute name: .gitattributes:2
 "^(\\(def[a-z]+ is not a valid attribute name: .gitattributes:3

What am I missing?  I tried googling, but from what turns up for me, it doesn't look like anyone else has ever tried to use this feature!

TIA,

--
David Abrahams
BoostPro Computing
http://boostpro.com




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