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git/diff-merges.c
Elijah Newren 0dec322d31 diff-merges: avoid history simplifications when diffing merges
Doing diffs for merges are special; they should typically avoid history
simplification.  For example, with

    git log --diff-merges=first-parent -- path

the default history simplification would remove merge commits from
consideration if the file "path" matched the second parent.  That is
counter to what the user wants when looking for first-parent diffs.
Similar comments can be made for --diff-merges=separate (which diffs
against both parents) and --diff-merges=remerge (which diffs against a
remerge of the merge commit).

However, history simplification still makes sense if not doing diffing
merges, and it also makes sense for the combined and dense-combined
forms of diffing merges (because both of those are defined to only show
a diff when the merge result at the relevant paths differs from *both*
parents).

So, for separate, first-parent, and remerge styles of diff-merges, turn
off history simplification.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-02 10:02:28 -08:00

180 lines
4.2 KiB
C

#include "diff-merges.h"
#include "revision.h"
typedef void (*diff_merges_setup_func_t)(struct rev_info *);
static void set_separate(struct rev_info *revs);
static diff_merges_setup_func_t set_to_default = set_separate;
static int suppress_m_parsing;
static void suppress(struct rev_info *revs)
{
revs->separate_merges = 0;
revs->first_parent_merges = 0;
revs->combine_merges = 0;
revs->dense_combined_merges = 0;
revs->combined_all_paths = 0;
revs->merges_imply_patch = 0;
revs->merges_need_diff = 0;
revs->remerge_diff = 0;
}
static void set_separate(struct rev_info *revs)
{
suppress(revs);
revs->separate_merges = 1;
revs->simplify_history = 0;
}
static void set_first_parent(struct rev_info *revs)
{
set_separate(revs);
revs->first_parent_merges = 1;
}
static void set_combined(struct rev_info *revs)
{
suppress(revs);
revs->combine_merges = 1;
revs->dense_combined_merges = 0;
}
static void set_dense_combined(struct rev_info *revs)
{
suppress(revs);
revs->combine_merges = 1;
revs->dense_combined_merges = 1;
}
static void set_remerge_diff(struct rev_info *revs)
{
suppress(revs);
revs->remerge_diff = 1;
revs->simplify_history = 0;
}
static diff_merges_setup_func_t func_by_opt(const char *optarg)
{
if (!strcmp(optarg, "off") || !strcmp(optarg, "none"))
return suppress;
if (!strcmp(optarg, "1") || !strcmp(optarg, "first-parent"))
return set_first_parent;
else if (!strcmp(optarg, "separate"))
return set_separate;
else if (!strcmp(optarg, "c") || !strcmp(optarg, "combined"))
return set_combined;
else if (!strcmp(optarg, "cc") || !strcmp(optarg, "dense-combined"))
return set_dense_combined;
else if (!strcmp(optarg, "r") || !strcmp(optarg, "remerge"))
return set_remerge_diff;
else if (!strcmp(optarg, "m") || !strcmp(optarg, "on"))
return set_to_default;
return NULL;
}
static void set_diff_merges(struct rev_info *revs, const char *optarg)
{
diff_merges_setup_func_t func = func_by_opt(optarg);
if (!func)
die(_("unknown value for --diff-merges: %s"), optarg);
func(revs);
/* NOTE: the merges_need_diff flag is cleared by func() call */
if (func != suppress)
revs->merges_need_diff = 1;
}
/*
* Public functions. They are in the order they are called.
*/
int diff_merges_config(const char *value)
{
diff_merges_setup_func_t func = func_by_opt(value);
if (!func)
return -1;
set_to_default = func;
return 0;
}
void diff_merges_suppress_m_parsing(void)
{
suppress_m_parsing = 1;
}
int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
{
int argcount = 1;
const char *optarg;
const char *arg = argv[0];
if (!suppress_m_parsing && !strcmp(arg, "-m")) {
set_to_default(revs);
} else if (!strcmp(arg, "-c")) {
set_combined(revs);
revs->merges_imply_patch = 1;
} else if (!strcmp(arg, "--cc")) {
set_dense_combined(revs);
revs->merges_imply_patch = 1;
} else if (!strcmp(arg, "--remerge-diff")) {
set_remerge_diff(revs);
revs->merges_imply_patch = 1;
} else if (!strcmp(arg, "--no-diff-merges")) {
suppress(revs);
} else if (!strcmp(arg, "--combined-all-paths")) {
revs->combined_all_paths = 1;
} else if ((argcount = parse_long_opt("diff-merges", argv, &optarg))) {
set_diff_merges(revs, optarg);
} else
return 0;
revs->explicit_diff_merges = 1;
return argcount;
}
void diff_merges_suppress(struct rev_info *revs)
{
suppress(revs);
}
void diff_merges_default_to_first_parent(struct rev_info *revs)
{
if (!revs->explicit_diff_merges)
revs->separate_merges = 1;
if (revs->separate_merges)
revs->first_parent_merges = 1;
}
void diff_merges_default_to_dense_combined(struct rev_info *revs)
{
if (!revs->explicit_diff_merges)
set_dense_combined(revs);
}
void diff_merges_set_dense_combined_if_unset(struct rev_info *revs)
{
if (!revs->combine_merges)
set_dense_combined(revs);
}
void diff_merges_setup_revs(struct rev_info *revs)
{
if (revs->combine_merges == 0)
revs->dense_combined_merges = 0;
if (revs->separate_merges == 0)
revs->first_parent_merges = 0;
if (revs->combined_all_paths && !revs->combine_merges)
die("--combined-all-paths makes no sense without -c or --cc");
if (revs->merges_imply_patch)
revs->diff = 1;
if (revs->merges_imply_patch || revs->merges_need_diff) {
if (!revs->diffopt.output_format)
revs->diffopt.output_format = DIFF_FORMAT_PATCH;
}
}