diff mbox series

diff: align move detection error handling with other options

Message ID 20181113213357.205769-1-sbeller@google.com (mailing list archive)
State New, archived
Headers show
Series diff: align move detection error handling with other options | expand

Commit Message

Stefan Beller Nov. 13, 2018, 9:33 p.m. UTC 
This changes the error handling for the options --color-moved-ws
and --color-moved-ws to be like the rest of the options.

Move the die() call out of parse_color_moved_ws into the parsing
of command line options. As the function returns a bit field, change
its signature to return an unsigned instead of an int; add a new bit
to signal errors. Once the error is signaled, we discard the other
bits, such that it doesn't matter if the error bit overlaps with any
other bit.

Signed-off-by: Stefan Beller <sbeller@google.com>
---

c.f.
./git -c diff.colormovedws=bogus diff HEAD
error: unknown color-moved-ws mode 'bogus'
fatal: unable to parse 'diff.colormovedws' from command-line config
./git -c core.abbrev=41 diff
error: abbrev length out of range: 41
fatal: unable to parse 'core.abbrev' from command-line config

./git diff --color=bogus
error: option `color' expects "always", "auto", or "never"
./git -c diff.colormovedws=bogus diff HEAD
error: unknown color-moved-ws mode 'bogus'
fatal: unable to parse 'diff.colormovedws' from command-line config


 diff.c                     | 25 ++++++++++++++++---------
 diff.h                     |  3 ++-
 t/t4015-diff-whitespace.sh | 18 ++++++++++++++++++
 3 files changed, 36 insertions(+), 10 deletions(-)

Comments

Junio C Hamano Nov. 14, 2018, 7:27 a.m. UTC | #1 
Stefan Beller <sbeller@google.com> writes:

>Subject: Re: [PATCH] diff: align move detection error handling with other options

When sending an updated version of existing topic, please make sure
you indicate as such with v$n etc.  I will assume that this is to
replace the patch queued on sb/diff-color-moved-config-option-fixup
topic.  Please do not assume that all messages on the References:
header are visible in the readers' MUA to show which thread it is a
response to.  At least a hint like v$n (or mentioning the name of
the topic branch if the previous round is already in 'pu') would
make the reader realize that the References: header can be used if
the reader wants to find in what context the patch is relevant,
especially when redoing a change whose previous round is more than a
week old, as we see too many changes in a day already.

> This changes the error handling for the options --color-moved-ws
> and --color-moved-ws to be like the rest of the options.
>
> Move the die() call out of parse_color_moved_ws into the parsing
> of command line options. As the function returns a bit field, change
> its signature to return an unsigned instead of an int; add a new bit
> to signal errors. Once the error is signaled, we discard the other
> bits, such that it doesn't matter if the error bit overlaps with any
> other bit.

OK.  That sound better than the original.

>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>
> c.f.
> ./git -c diff.colormovedws=bogus diff HEAD
> error: unknown color-moved-ws mode 'bogus'
> fatal: unable to parse 'diff.colormovedws' from command-line config

These double messages may be something we want to fix eventually,
but I think that the issue is not specific to the config callback of
diff API, but something the config API needs to support to allow its
users produce a better single message (the first part is merely
giving a more detailed explanation why Git was unable to parse, and
should ideally be folded into the second part).

More generally, even if git_diff_ui_config() was called, as long as
we do not do the "--color-moved" and "--color-moved-ws" operations,
the user shouldn't even get an "unknown mode" message, let alone
"fatal".  The above (and other existing uses of "return -1"s in the
same config callback) should actually become an example of what not
to do, as "diff HEAD" does not *care* what value that variable has.

But again, fixing that anti-pattern is a much larger change.  Once
we move diff.c to the more modern git_config_get*() based interface,
instead of the old style git_config() callback based interface, it
would become easier to update it so that the complaint will be given
(and kill the command) only when a variable whose value actually
_matters_ is unparsable.

Thanks.
diff mbox series

Patch

diff --git a/diff.c b/diff.c
index 8647db3d30..d7d467b605 100644
--- a/diff.c
+++ b/diff.c
@@ -291,7 +291,7 @@  static int parse_color_moved(const char *arg)
 		return error(_("color moved setting must be one of 'no', 'default', 'blocks', 'zebra', 'dimmed-zebra', 'plain'"));
 }
 
-static int parse_color_moved_ws(const char *arg)
+static unsigned parse_color_moved_ws(const char *arg)
 {
 	int ret = 0;
 	struct string_list l = STRING_LIST_INIT_DUP;
@@ -312,15 +312,19 @@  static int parse_color_moved_ws(const char *arg)
 			ret |= XDF_IGNORE_WHITESPACE;
 		else if (!strcmp(sb.buf, "allow-indentation-change"))
 			ret |= COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE;
-		else
-			error(_("ignoring unknown color-moved-ws mode '%s'"), sb.buf);
+		else {
+			ret |= COLOR_MOVED_WS_ERROR;
+			error(_("unknown color-moved-ws mode '%s', possible values are 'ignore-space-change', 'ignore-space-at-eol', 'ignore-all-space', 'allow-indentation-change'"), sb.buf);
+		}
 
 		strbuf_release(&sb);
 	}
 
 	if ((ret & COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) &&
-	    (ret & XDF_WHITESPACE_FLAGS))
-		die(_("color-moved-ws: allow-indentation-change cannot be combined with other white space modes"));
+	    (ret & XDF_WHITESPACE_FLAGS)) {
+		error(_("color-moved-ws: allow-indentation-change cannot be combined with other white space modes"));
+		ret |= COLOR_MOVED_WS_ERROR;
+	}
 
 	string_list_clear(&l, 0);
 
@@ -341,8 +345,8 @@  int git_diff_ui_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 	if (!strcmp(var, "diff.colormovedws")) {
-		int cm = parse_color_moved_ws(value);
-		if (cm < 0)
+		unsigned cm = parse_color_moved_ws(value);
+		if (cm & COLOR_MOVED_WS_ERROR)
 			return -1;
 		diff_color_moved_ws_default = cm;
 		return 0;
@@ -5032,10 +5036,13 @@  int diff_opt_parse(struct diff_options *options,
 	else if (skip_prefix(arg, "--color-moved=", &arg)) {
 		int cm = parse_color_moved(arg);
 		if (cm < 0)
-			die("bad --color-moved argument: %s", arg);
+			return error("bad --color-moved argument: %s", arg);
 		options->color_moved = cm;
 	} else if (skip_prefix(arg, "--color-moved-ws=", &arg)) {
-		options->color_moved_ws_handling = parse_color_moved_ws(arg);
+		unsigned cm = parse_color_moved_ws(arg);
+		if (cm & COLOR_MOVED_WS_ERROR)
+			return -1;
+		options->color_moved_ws_handling = cm;
 	} else if (skip_to_optional_arg_default(arg, "--color-words", &options->word_regex, NULL)) {
 		options->use_color = 1;
 		options->word_diff = DIFF_WORDS_COLOR;
diff --git a/diff.h b/diff.h
index ce5e8a8183..9e8061ca29 100644
--- a/diff.h
+++ b/diff.h
@@ -225,7 +225,8 @@  struct diff_options {
 
 	/* XDF_WHITESPACE_FLAGS regarding block detection are set at 2, 3, 4 */
 	#define COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE (1<<5)
-	int color_moved_ws_handling;
+	#define COLOR_MOVED_WS_ERROR (1<<0)
+	unsigned color_moved_ws_handling;
 
 	struct repository *repo;
 };
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index a9fb226c5a..9a3e4fdfec 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1890,6 +1890,24 @@  test_expect_success 'compare whitespace delta across moved blocks' '
 	test_cmp expected actual
 '
 
+test_expect_success 'bogus settings in move detection erroring out' '
+	test_must_fail git diff --color-moved=bogus 2>err &&
+	test_i18ngrep "must be one of" err &&
+	test_i18ngrep bogus err &&
+
+	test_must_fail git -c diff.colormoved=bogus diff 2>err &&
+	test_i18ngrep "must be one of" err &&
+	test_i18ngrep "from command-line config" err &&
+
+	test_must_fail git diff --color-moved-ws=bogus 2>err &&
+	test_i18ngrep "possible values" err &&
+	test_i18ngrep bogus err &&
+
+	test_must_fail git -c diff.colormovedws=bogus diff 2>err &&
+	test_i18ngrep "possible values" err &&
+	test_i18ngrep "from command-line config" err
+'
+
 test_expect_success 'compare whitespace delta incompatible with other space options' '
 	test_must_fail git diff \
 		--color-moved-ws=allow-indentation-change,ignore-all-space \