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Originally, with no base, Git gave P4Merge $LOCAL as a dummy base:
p4merge "$LOCAL" "$LOCAL" "$REMOTE" "$MERGED"
Commit 0a0ec7bd changed this to:
p4merge "empty file" "$LOCAL" "$REMOTE" "$MERGED"
to avoid the problem of being unable to save in some circumstances with
similar inputs.
Unfortunately this approach produces much worse results on differing
inputs. P4Merge really regards the blank file as the base, and once you
have just a couple of differences between the two branches you end up
with one a massive full-file conflict. The 3-way diff is not readable,
and you have to invoke "difftool MERGE_HEAD HEAD" manually to get a
useful view.
The original approach appears to have invoked special 2-way merge
behaviour in P4Merge that occurs only if the base filename is "" or
equal to the left input. You get a good visual comparison, and it does
not auto-resolve differences. (Normally if one branch matched the base,
it would autoresolve to the other branch).
But there appears to be no way of getting this 2-way behaviour and being
able to reliably save. Having base==left appears to be triggering other
assumptions. There are tricks the user can use to force the save icon
on, but it's not intuitive.
So we now follow a suggestion given in the original patch's discussion:
generate a virtual base, consisting of the lines common to the two
branches. This is the same as the technique used in resolve and octopus
merges, so we relocate that code to a shared function.
Note that if there are no differences at the same location, this
technique can lead to automatic resolution without conflict, combining
everything from the 2 files. As with the other merges using this
technique, we assume the user will inspect the result before saving.
Signed-off-by: Kevin Bracey <kevin@bracey.fi>
Reviewed-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
93 lines
2.7 KiB
Text
93 lines
2.7 KiB
Text
git-sh-setup(1)
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===============
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NAME
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----
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git-sh-setup - Common Git shell script setup code
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SYNOPSIS
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--------
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[verse]
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'. "$(git --exec-path)/git-sh-setup"'
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DESCRIPTION
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-----------
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This is not a command the end user would want to run. Ever.
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This documentation is meant for people who are studying the
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Porcelain-ish scripts and/or are writing new ones.
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The 'git sh-setup' scriptlet is designed to be sourced (using
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`.`) by other shell scripts to set up some variables pointing at
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the normal Git directories and a few helper shell functions.
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Before sourcing it, your script should set up a few variables;
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`USAGE` (and `LONG_USAGE`, if any) is used to define message
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given by `usage()` shell function. `SUBDIRECTORY_OK` can be set
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if the script can run from a subdirectory of the working tree
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(some commands do not).
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The scriptlet sets `GIT_DIR` and `GIT_OBJECT_DIRECTORY` shell
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variables, but does *not* export them to the environment.
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FUNCTIONS
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---------
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die::
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exit after emitting the supplied error message to the
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standard error stream.
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usage::
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die with the usage message.
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set_reflog_action::
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set the message that will be recorded to describe the
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end-user action in the reflog, when the script updates a
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ref.
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git_editor::
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runs an editor of user's choice (GIT_EDITOR, core.editor, VISUAL or
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EDITOR) on a given file, but error out if no editor is specified
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and the terminal is dumb.
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is_bare_repository::
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outputs `true` or `false` to the standard output stream
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to indicate if the repository is a bare repository
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(i.e. without an associated working tree).
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cd_to_toplevel::
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runs chdir to the toplevel of the working tree.
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require_work_tree::
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checks if the current directory is within the working tree
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of the repository, and otherwise dies.
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require_work_tree_exists::
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checks if the working tree associated with the repository
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exists, and otherwise dies. Often done before calling
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cd_to_toplevel, which is impossible to do if there is no
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working tree.
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require_clean_work_tree <action> [<hint>]::
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checks that the working tree and index associated with the
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repository have no uncommitted changes to tracked files.
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Otherwise it emits an error message of the form `Cannot
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<action>: <reason>. <hint>`, and dies. Example:
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+
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----------------
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require_clean_work_tree rebase "Please commit or stash them."
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----------------
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get_author_ident_from_commit::
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outputs code for use with eval to set the GIT_AUTHOR_NAME,
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GIT_AUTHOR_EMAIL and GIT_AUTHOR_DATE variables for a given commit.
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create_virtual_base::
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modifies the first file so only lines in common with the
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second file remain. If there is insufficient common material,
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then the first file is left empty. The result is suitable
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as a virtual base input for a 3-way merge.
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GIT
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---
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Part of the linkgit:git[1] suite
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