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Scenario: clone-from-submodule, under the monorepo's line endings

Git applies a repository's .gitattributes to its own files, never to a submodule's. Once the submodule is a folder, the monorepo's attributes would apply to its files too. Where they would change a checkout -- text and eol for line endings, as here, filter, ident and working-tree-encoding -- the conversion refuses, and names the line that unsets them for the folder. With that line committed, it converts.

  • Monorepo, on main: .gitattributes wants .bat files with CRLF. vendor/a/ is a submodule of the upstream, checked out at add run.bat.
  • Upstream ($UPSTREAM, reached as https://git.example.com/a.git): seed, newer, then build.bat committed with CRLF and run.bat with LF.

Output​

setup.bash builds this state:

$ build_scenario scenario_monorepo_line_endings https://git.example.com/a.git
$ cat .gitattributes
*.bat text eol=crlf

The submodule is a repository of its own, and none of its attributes are set:

$ git -C vendor/a check-attr text eol -- build.bat run.bat
build.bat: text: unspecified
build.bat: eol: unspecified
run.bat: text: unspecified
run.bat: eol: unspecified

In the monorepo, the root's would apply. The conversion refuses, and nothing changes:

$ git splice clone --from-submodule vendor/a
===  vendor/a: fetching https://git.example.com/a.git
!!   vendor/a: attributes in .gitattributes or above it would change how Git checks out or stores some of its files, unlike in upstream -- add 'vendor/a/** !text !eol !filter !ident !working-tree-encoding' to .gitattributes, commit it, and run clone again
[1]

The line it names unsets them, and the other attributes that change a checkout, for the folder again. Commit it:

$ echo 'vendor/a/** !text !eol !filter !ident !working-tree-encoding' >>.gitattributes && git commit -q -m "keep the monorepo's line endings off vendor/a" .gitattributes
$ git splice clone --from-submodule vendor/a
===  vendor/a: fetching https://git.example.com/a.git
ok   vendor/a: cloned f758343 from the submodule
===  vendor/a: pinned at f758343, as the submodule was -- pull brings in nothing and push refuses on main until it follows a branch: git config --file vendor/a/.splice --unset upstream.origin.default-pin
===  vendor/a: the submodule's repository stays in .*/monorepo/\.git/modules/vendor/a -- remove it once you don't need it (regex)
$ git check-attr text eol -- vendor/a/build.bat
vendor/a/build.bat: text: unspecified
vendor/a/build.bat: eol: unspecified

Nothing shows as changed:

$ git status --short

Attributes added later​

The line wins over the lines before it in the same file. A rule added after it applies to the splice again, a known gap (#311):

$ printf '*.txt text eol=crlf\n' >>.gitattributes && git check-attr eol -- vendor/a/file.txt
vendor/a/file.txt: eol: crlf

So does one in a .gitattributes deeper than the line's, between the root and the splice:

$ git checkout -q -- .gitattributes && printf '*.txt text eol=crlf\n' >vendor/.gitattributes && git check-attr eol -- vendor/a/file.txt
vendor/a/file.txt: eol: crlf
$ rm vendor/.gitattributes

Without the line​

With the .gitattributes from before the line, Git stores build.bat with LF the next time it's added, and the next push would send that change to the upstream:

$ git checkout -q HEAD~2 -- .gitattributes && git add --renormalize vendor/a && git status --short
M  .gitattributes
M  vendor/a/build.bat

And a checkout would give run.bat, which the submodule had with LF, CRLF instead (^M):

$ rm vendor/a/run.bat && git checkout -- vendor/a/run.bat && cat -A vendor/a/run.bat
echo run^M$