git/ll-merge.h
Elijah Newren 35f6967161 ll-merge: make callers responsible for showing warnings
Since some callers may want to send warning messages to somewhere other
than stdout/stderr, stop printing "warning: Cannot merge binary files"
from ll-merge and instead modify the return status of ll_merge() to
indicate when a merge of binary files has occurred.  Message printing
probably does not belong in a "low-level merge" anyway.

This commit continues printing the message as-is, just from the callers
instead of within ll_merge().  Future changes will start handling the
message differently in the merge-ort codepath.

There was one special case here: the callers in rerere.c do NOT check
for and print such a message; since those code paths explicitly skip
over binary files, there is no reason to check for a return status of
LL_MERGE_BINARY_CONFLICT or print the related message.

Note that my methodology included first modifying ll_merge() to return
a struct, so that the compiler would catch all the callers for me and
ensure I had modified all of them.  After modifying all of them, I then
changed the struct to an enum.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-02 10:02:27 -08:00

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/*
* Low level 3-way in-core file merge.
*/
#ifndef LL_MERGE_H
#define LL_MERGE_H
#include "xdiff/xdiff.h"
/**
*
* Calling sequence:
* ----------------
*
* - Prepare a `struct ll_merge_options` to record options.
* If you have no special requests, skip this and pass `NULL`
* as the `opts` parameter to use the default options.
*
* - Allocate an mmbuffer_t variable for the result.
*
* - Allocate and fill variables with the file's original content
* and two modified versions (using `read_mmfile`, for example).
*
* - Call `ll_merge()`.
*
* - Read the merged content from `result_buf.ptr` and `result_buf.size`.
*
* - Release buffers when finished. A simple
* `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr);
* free(result_buf.ptr);` will do.
*
* If the modifications do not merge cleanly, `ll_merge` will return a
* nonzero value and `result_buf` will generally include a description of
* the conflict bracketed by markers such as the traditional `<<<<<<<`
* and `>>>>>>>`.
*
* The `ancestor_label`, `our_label`, and `their_label` parameters are
* used to label the different sides of a conflict if the merge driver
* supports this.
*/
struct index_state;
/**
* This describes the set of options the calling program wants to affect
* the operation of a low-level (single file) merge.
*/
struct ll_merge_options {
/**
* Behave as though this were part of a merge between common ancestors in
* a recursive merge (merges of binary files may need to be handled
* differently in such cases, for example). If a helper program is
* specified by the `[merge "<driver>"] recursive` configuration, it will
* be used.
*/
unsigned virtual_ancestor : 1;
/**
* Resolve local conflicts automatically in favor of one side or the other
* (as in 'git merge-file' `--ours`/`--theirs`/`--union`). Can be `0`,
* `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`,
* or `XDL_MERGE_FAVOR_UNION`.
*/
unsigned variant : 2;
/**
* Resmudge and clean the "base", "theirs" and "ours" files before merging.
* Use this when the merge is likely to have overlapped with a change in
* smudge/clean or end-of-line normalization rules.
*/
unsigned renormalize : 1;
/**
* Increase the length of conflict markers so that nested conflicts
 * can be differentiated.
*/
unsigned extra_marker_size;
/* Extra xpparam_t flags as defined in xdiff/xdiff.h. */
long xdl_opts;
};
enum ll_merge_result {
LL_MERGE_ERROR = -1,
LL_MERGE_OK = 0,
LL_MERGE_CONFLICT,
LL_MERGE_BINARY_CONFLICT,
};
/**
* Perform a three-way single-file merge in core. This is a thin wrapper
* around `xdl_merge` that takes the path and any merge backend specified in
* `.gitattributes` or `.git/info/attributes` into account.
* Returns 0 for a clean merge.
*/
enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
const char *path,
mmfile_t *ancestor, const char *ancestor_label,
mmfile_t *ours, const char *our_label,
mmfile_t *theirs, const char *their_label,
struct index_state *istate,
const struct ll_merge_options *opts);
int ll_merge_marker_size(struct index_state *istate, const char *path);
void reset_merge_attributes(void);
#endif