diff mercurial/helptext/merge-tools.txt @ 43632:2e017696181f

help: create packages for the help text These files need to be loaded as resources with PyOxidizer, instead of using filesystem representations. AFAICT, the resource loading mechanisms only work for the named package given to it, and can't reach into a subdirectory. While here, the `help` directory is renamed to `helptext`. Without this, trying to load external help text crashed in mercurial/help.py when importing `.i18n`, saying there's no `mercurial.help.i18n` module. Differential Revision: https://phab.mercurial-scm.org/D7376
author Matt Harbison <matt_harbison@yahoo.com>
date Wed, 13 Nov 2019 21:52:25 -0500
parents mercurial/help/merge-tools.txt@0dfcc348d383
children
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+To merge files Mercurial uses merge tools.
+
+A merge tool combines two different versions of a file into a merged
+file. Merge tools are given the two files and the greatest common
+ancestor of the two file versions, so they can determine the changes
+made on both branches.
+
+Merge tools are used both for :hg:`resolve`, :hg:`merge`, :hg:`update`,
+:hg:`backout` and in several extensions.
+
+Usually, the merge tool tries to automatically reconcile the files by
+combining all non-overlapping changes that occurred separately in
+the two different evolutions of the same initial base file. Furthermore, some
+interactive merge programs make it easier to manually resolve
+conflicting merges, either in a graphical way, or by inserting some
+conflict markers. Mercurial does not include any interactive merge
+programs but relies on external tools for that.
+
+Available merge tools
+=====================
+
+External merge tools and their properties are configured in the
+merge-tools configuration section - see hgrc(5) - but they can often just
+be named by their executable.
+
+A merge tool is generally usable if its executable can be found on the
+system and if it can handle the merge. The executable is found if it
+is an absolute or relative executable path or the name of an
+application in the executable search path. The tool is assumed to be
+able to handle the merge if it can handle symlinks if the file is a
+symlink, if it can handle binary files if the file is binary, and if a
+GUI is available if the tool requires a GUI.
+
+There are some internal merge tools which can be used. The internal
+merge tools are:
+
+.. internaltoolsmarker
+
+Internal tools are always available and do not require a GUI but will
+by default not handle symlinks or binary files. See next section for
+detail about "actual capabilities" described above.
+
+Choosing a merge tool
+=====================
+
+Mercurial uses these rules when deciding which merge tool to use:
+
+1. If a tool has been specified with the --tool option to merge or resolve, it
+   is used.  If it is the name of a tool in the merge-tools configuration, its
+   configuration is used. Otherwise the specified tool must be executable by
+   the shell.
+
+2. If the ``HGMERGE`` environment variable is present, its value is used and
+   must be executable by the shell.
+
+3. If the filename of the file to be merged matches any of the patterns in the
+   merge-patterns configuration section, the first usable merge tool
+   corresponding to a matching pattern is used.
+
+4. If ui.merge is set it will be considered next. If the value is not the name
+   of a configured tool, the specified value is used and must be executable by
+   the shell. Otherwise the named tool is used if it is usable.
+
+5. If any usable merge tools are present in the merge-tools configuration
+   section, the one with the highest priority is used.
+
+6. If a program named ``hgmerge`` can be found on the system, it is used - but
+   it will by default not be used for symlinks and binary files.
+
+7. If the file to be merged is not binary and is not a symlink, then
+   internal ``:merge`` is used.
+
+8. Otherwise, ``:prompt`` is used.
+
+For historical reason, Mercurial treats merge tools as below while
+examining rules above.
+
+==== =============== ====== =======
+step specified via   binary symlink
+==== =============== ====== =======
+1.   --tool          o/o    o/o
+2.   HGMERGE         o/o    o/o
+3.   merge-patterns  o/o(*) x/?(*)
+4.   ui.merge        x/?(*) x/?(*)
+==== =============== ====== =======
+
+Each capability column indicates Mercurial behavior for
+internal/external merge tools at examining each rule.
+
+- "o": "assume that a tool has capability"
+- "x": "assume that a tool does not have capability"
+- "?": "check actual capability of a tool"
+
+If ``merge.strict-capability-check`` configuration is true, Mercurial
+checks capabilities of merge tools strictly in (*) cases above (= each
+capability column becomes "?/?"). It is false by default for backward
+compatibility.
+
+.. note::
+
+   After selecting a merge program, Mercurial will by default attempt
+   to merge the files using a simple merge algorithm first. Only if it doesn't
+   succeed because of conflicting changes will Mercurial actually execute the
+   merge program. Whether to use the simple merge algorithm first can be
+   controlled by the premerge setting of the merge tool. Premerge is enabled by
+   default unless the file is binary or a symlink.
+
+See the merge-tools and ui sections of hgrc(5) for details on the
+configuration of merge tools.