git mailinfo splits a message into headers, commit message, and patch text, but does not actually parse the patch text. As a result, the patch portion produced by git mailinfo can contain something that looks like a patch, but actually isn't.
Is there a way to get the patch data, as parsed by git apply or git am, and dump it back in patch format, without actually applying the patch to a working tree?
Junio C HamanoRe: git mailinfo with patch parser
Florian Weimer <fw@deneb.enyo.de> writes:
> git mailinfo splits a message into headers, commit message, and patch > text, but does not actually parse the patch text. As a result, the > patch portion produced by git mailinfo can contain something that > looks like a patch, but actually isn't.
Yes, mailinfo is about splitting the header, log message and the remainder, and parsing the remainder to use it as a patch text is left to the consumer of the "patch" file it produces.
> Is there a way to get the patch data, as parsed by git apply or git > am, and dump it back in patch format, without actually applying the > patch to a working tree?
So, "the patch data as used by apply" is what you get from mailinfo. If it is a patch that applies to what you have in the working tree and/or the index is something you can/must ask "git apply". IOW, when "git mailinfo" stored in $GIT_DIR/rebase-apply/patch the "remainder" of the message, you could
git apply --check [--index] $GIT_DIR/rebase-apply/patch
to see if it is an OK patch. If it is, then there is no need to further "dump it back in patch format"; what you just fed to "apply --check" is already in the patch format.
Re: git mailinfo with patch parser
* Junio C. Hamano:
>> Is there a way to get the patch data, as parsed by git apply or git >> am, and dump it back in patch format, without actually applying the >> patch to a working tree? > > So, "the patch data as used by apply" is what you get from mailinfo. > If it is a patch that applies to what you have in the working tree > and/or the index is something you can/must ask "git apply". IOW, > when "git mailinfo" stored in $GIT_DIR/rebase-apply/patch the > "remainder" of the message, you could > > git apply --check [--index] $GIT_DIR/rebase-apply/patch > > to see if it is an OK patch. If it is, then there is no need to > further "dump it back in patch format"; what you just fed to "apply > --check" is already in the patch format.
Yes, but that requires a fully patched up Git repository containing the right blobs.
We know from experience that it is easy for humans to misread patches and fail to notice that certain patch hunks are actually ignored by git apply and similar tools. If there was a way to feed the patch through the parser and serialize it back, these discrepancies would be more noticeable, I think. Any data ignored by git apply/git am would be missing from the output.