[PATCH 00/10] fix bug, use existing enums

I have some feature changes planned for parse-options.[ch], including
ones that allow us to delete some boilerplate (and sometimes buggy)
code in built-ins by having the API do heavier lifting.

In adding anything to the API I've found it hard to deal with it using
its own enums inconsistently, sometimes it's an "int", sometimes it's
the "enum", and having the "default" cases makes it hard to assert
that you've added things to all the right places.

2-6,7-10/10 is that rather straightforward conversion. 1,7/10 also
have fixes to existing bugs that happened due to mixing up the enum
fields in one way or the other.

Ævar Arnfjörð Bjarmason (10):
  parse-options.h: move PARSE_OPT_SHELL_EVAL between enums
  parse-options.[ch]: consistently use "enum parse_opt_flags"
  parse-options.[ch]: consistently use "enum parse_opt_result"
  parse-options.c: use exhaustive "case" arms for "enum parse_opt_type"
  parse-options.h: make the "flags" in "struct option" an enum
  parse-options.c: move optname() earlier in the file
  commit-graph: stop using optname()
  parse-options.[ch]: make opt{bug,name}() "static"
  parse-options tests: test optname() output
  parse-options: change OPT_{SHORT,UNSET} to an enum

 builtin/blame.c          |   3 +
 builtin/commit-graph.c   |   3 +-
 builtin/shortlog.c       |   3 +
 parse-options.c          | 116 ++++++++++++++++++++++++++-------------
 parse-options.h          |  26 ++++-----
 t/t0040-parse-options.sh |  42 +++++++++++++-
 6 files changed, 138 insertions(+), 55 deletions(-)

-- 
2.33.0.1340.ge9f77250f2b

Fix a bad landmine of a bug which has been with us ever since
PARSE_OPT_SHELL_EVAL was added in 47e9cd28f8a (parseopt: wrap
rev-parse --parseopt usage for eval consumption, 2010-06-12).

It's an argument to parse_options() and should therefore be in "enum
parse_opt_flags", but it was added to the per-option "enum
parse_opt_option_flags" by mistake.

Therefore as soon as we'd have an enum member in the former that
reached its value of "1 << 8" we'd run into a seemingly bizarre bug
where that new option would turn on the unrelated PARSE_OPT_SHELL_EVAL
in "git rev-parse --parseopt" by proxy.

I manually checked that no other enum members suffered from such
overlap, by setting the values to non-overlapping values, and making
the relevant codepaths BUG() out if the given value was above/below
the expected (excluding flags=0 in the case of "enum
parse_opt_flags").

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.h b/parse-options.h
index 39d90882548..3a3176ae65c 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -33,6 +33,7 @@ enum parse_opt_flags {
 	PARSE_OPT_KEEP_UNKNOWN = 1 << 3,
 	PARSE_OPT_NO_INTERNAL_HELP = 1 << 4,
 	PARSE_OPT_ONE_SHOT = 1 << 5,
+	PARSE_OPT_SHELL_EVAL = 1 << 6,
 };
 
 enum parse_opt_option_flags {

@@ -44,7 +45,6 @@ enum parse_opt_option_flags {
 	PARSE_OPT_NODASH = 1 << 5,
 	PARSE_OPT_LITERAL_ARGHELP = 1 << 6,
 	PARSE_OPT_FROM_ALIAS = 1 << 7,
-	PARSE_OPT_SHELL_EVAL = 1 << 8,
 	PARSE_OPT_NOCOMPLETE = 1 << 9,
 	PARSE_OPT_COMP_ARG = 1 << 10,
 	PARSE_OPT_CMDMODE = 1 << 11,

-- 
2.33.0.1340.ge9f77250f2b

Use the "enum parse_opt_flags" instead of an "int flags" as arguments
to the various functions in parse-options.c. This will help to catch
cases where we're not handling cases in switch statements, and
generally make it obvious which "flags" we're referring to in this
case.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 13 ++++++++-----
 parse-options.h |  6 ++++--
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 55c5821b08d..9dce8b7f8a8 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -481,7 +481,8 @@ static void parse_options_check(const struct option *opts)
 
 static void parse_options_start_1(struct parse_opt_ctx_t *ctx,
 				  int argc, const char **argv, const char *prefix,
-				  const struct option *options, int flags)
+				  const struct option *options,
+				  enum parse_opt_flags flags)
 {
 	ctx->argc = argc;
 	ctx->argv = argv;

@@ -506,7 +507,8 @@ static void parse_options_start_1(struct parse_opt_ctx_t *ctx,
 
 void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 int argc, const char **argv, const char *prefix,
-			 const struct option *options, int flags)
+			 const struct option *options,
+			 enum parse_opt_flags flags)
 {
 	memset(ctx, 0, sizeof(*ctx));
 	parse_options_start_1(ctx, argc, argv, prefix, options, flags);

@@ -838,8 +840,9 @@ int parse_options_end(struct parse_opt_ctx_t *ctx)
 }
 
 int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options, const char * const usagestr[],
-		  int flags)
+		  const struct option *options,
+		  const char * const usagestr[],
+		  enum parse_opt_flags flags)
 {
 	struct parse_opt_ctx_t ctx;
 	struct option *real_options;

@@ -861,7 +864,7 @@ int parse_options(int argc, const char **argv, const char *prefix,
 	case PARSE_OPT_NON_OPTION:
 	case PARSE_OPT_DONE:
 		break;
-	default: /* PARSE_OPT_UNKNOWN */
+	case PARSE_OPT_UNKNOWN:
 		if (ctx.argv[0][1] == '-') {
 			error(_("unknown option `%s'"), ctx.argv[0] + 2);
 		} else if (isascii(*ctx.opt)) {

diff --git a/parse-options.h b/parse-options.h
index 3a3176ae65c..fb5aafd4f7b 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -213,7 +213,8 @@ struct option {
  */
 int parse_options(int argc, const char **argv, const char *prefix,
 		  const struct option *options,
-		  const char * const usagestr[], int flags);
+		  const char * const usagestr[],
+		  enum parse_opt_flags flags);
 
 NORETURN void usage_with_options(const char * const *usagestr,
 				 const struct option *options);

@@ -270,7 +271,8 @@ struct parse_opt_ctx_t {
 
 void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 int argc, const char **argv, const char *prefix,
-			 const struct option *options, int flags);
+			 const struct option *options,
+			 enum parse_opt_flags flags);
 
 int parse_options_step(struct parse_opt_ctx_t *ctx,
 		       const struct option *options,

-- 
2.33.0.1340.ge9f77250f2b

Use the "enum parse_opt_result" instead of an "int flags" as the
return value of the applicable functions in parse-options.c.

This will help catch future bugs, such as the missing "case" arms in
the two existing users of the API in "blame.c" and "shortlog.c". A
third caller in 309be813c9b (update-index: migrate to parse-options
API, 2010-12-01) was already checking for these.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 builtin/blame.c    |  3 +++
 builtin/shortlog.c |  3 +++
 parse-options.c    | 15 ++++++++-------
 parse-options.h    | 15 ++++++++-------
 4 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/builtin/blame.c b/builtin/blame.c
index 641523ff9af..9273fb222d5 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c

@@ -917,6 +917,9 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 			    PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_ARGV0);
 	for (;;) {
 		switch (parse_options_step(&ctx, options, blame_opt_usage)) {
+		case PARSE_OPT_NON_OPTION:
+		case PARSE_OPT_UNKNOWN:
+			break;
 		case PARSE_OPT_HELP:
 		case PARSE_OPT_ERROR:
 			exit(129);

diff --git a/builtin/shortlog.c b/builtin/shortlog.c
index 3e7ab1ca821..e7f7af5de3f 100644
--- a/builtin/shortlog.c
+++ b/builtin/shortlog.c

@@ -374,6 +374,9 @@ int cmd_shortlog(int argc, const char **argv, const char *prefix)
 
 	for (;;) {
 		switch (parse_options_step(&ctx, options, shortlog_usage)) {
+		case PARSE_OPT_NON_OPTION:
+		case PARSE_OPT_UNKNOWN:
+			break;
 		case PARSE_OPT_HELP:
 		case PARSE_OPT_ERROR:
 			exit(129);

diff --git a/parse-options.c b/parse-options.c
index 9dce8b7f8a8..799cd884f2b 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -703,9 +703,9 @@ static int usage_with_options_internal(struct parse_opt_ctx_t *,
 				       const char * const *,
 				       const struct option *, int, int);
 
-int parse_options_step(struct parse_opt_ctx_t *ctx,
-		       const struct option *options,
-		       const char * const usagestr[])
+enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
+					 const struct option *options,
+					 const char * const usagestr[])
 {
 	int internal_help = !(ctx->flags & PARSE_OPT_NO_INTERNAL_HELP);
 

@@ -839,10 +839,11 @@ int parse_options_end(struct parse_opt_ctx_t *ctx)
 	return ctx->cpidx + ctx->argc;
 }
 
-int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options,
-		  const char * const usagestr[],
-		  enum parse_opt_flags flags)
+enum parse_opt_result parse_options(int argc, const char **argv,
+				    const char *prefix,
+				    const struct option *options,
+				    const char * const usagestr[],
+				    enum parse_opt_flags flags)
 {
 	struct parse_opt_ctx_t ctx;
 	struct option *real_options;

diff --git a/parse-options.h b/parse-options.h
index fb5aafd4f7b..d931300f4d6 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -211,10 +211,11 @@ struct option {
  * untouched and parse_options() returns the number of options
  * processed.
  */
-int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options,
-		  const char * const usagestr[],
-		  enum parse_opt_flags flags);
+enum parse_opt_result parse_options(int argc, const char **argv,
+				    const char *prefix,
+				    const struct option *options,
+				    const char * const usagestr[],
+				    enum parse_opt_flags flags);
 
 NORETURN void usage_with_options(const char * const *usagestr,
 				 const struct option *options);

@@ -274,9 +275,9 @@ void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 const struct option *options,
 			 enum parse_opt_flags flags);
 
-int parse_options_step(struct parse_opt_ctx_t *ctx,
-		       const struct option *options,
-		       const char * const usagestr[]);
+enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
+					 const struct option *options,
+					 const char * const usagestr[]);
 
 int parse_options_end(struct parse_opt_ctx_t *ctx);
 

-- 
2.33.0.1340.ge9f77250f2b

Change code in get_value(), parse_options_check() etc. to do away with
the "default" case in favor of exhaustively checking the relevant
fields.

The added "return -1" is needed for the GCC version commented on
inline, my local clang 11.0.1-2 does not require it. Let's add it for
now to appease GCC.

The added "special types" etc. comments correspond to the relevant
comments and ordering on the "enum parse_opt_type". Let's try to keep
the same order and commentary as there where possible for
clarity. This doesn't reach that end-state, and due to the different
handling of options it's probably not worth it to get there, but let's
match its ordering where it's easy to do so.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 43 ++++++++++++++++++++++++++++++++++++++-----
 parse-options.h |  2 +-
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 799cd884f2b..733cbfa8821 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -219,9 +219,14 @@ static enum parse_opt_result get_value(struct parse_opt_ctx_t *p,
 				     optname(opt, flags));
 		return 0;
 
-	default:
+	/* special types */
+	case OPTION_END:
+	case OPTION_GROUP:
+	case OPTION_NUMBER:
+	case OPTION_ALIAS:
 		BUG("opt->type %d should not happen", opt->type);
 	}
+	return -1; /* gcc 10.2.1-6's -Werror=return-type */
 }
 
 static enum parse_opt_result parse_short_opt(struct parse_opt_ctx_t *p,

@@ -468,8 +473,15 @@ static void parse_options_check(const struct option *opts)
 			BUG("OPT_ALIAS() should not remain at this point. "
 			    "Are you using parse_options_step() directly?\n"
 			    "That case is not supported yet.");
-		default:
-			; /* ok. (usually accepts an argument) */
+
+		case OPTION_BITOP:
+		case OPTION_END:
+		case OPTION_FILENAME:
+		case OPTION_GROUP:
+		case OPTION_INTEGER:
+		case OPTION_MAGNITUDE:
+		case OPTION_STRING:
+			break;
 		}
 		if (opts->argh &&
 		    strcspn(opts->argh, " _") != strlen(opts->argh))

@@ -543,7 +555,15 @@ static void show_negated_gitcomp(const struct option *opts, int show_all,
 		case OPTION_SET_INT:
 			has_unset_form = 1;
 			break;
-		default:
+		/* special types */
+		case OPTION_END:
+		case OPTION_GROUP:
+		case OPTION_NUMBER:
+		case OPTION_ALIAS:
+		/* options with no arguments */
+		case OPTION_BITOP:
+		/* options with arguments (usually) */
+		case OPTION_LOWLEVEL_CALLBACK:
 			break;
 		}
 		if (!has_unset_form)

@@ -593,7 +613,20 @@ static int show_gitcomp(const struct option *opts, int show_all)
 				break;
 			suffix = "=";
 			break;
-		default:
+		/* special types */
+		case OPTION_END:
+		case OPTION_NUMBER:
+		case OPTION_ALIAS:
+
+		/* options with no arguments */
+		case OPTION_BIT:
+		case OPTION_NEGBIT:
+		case OPTION_BITOP:
+		case OPTION_COUNTUP:
+		case OPTION_SET_INT:
+
+		/* options with arguments (usually) */
+		case OPTION_LOWLEVEL_CALLBACK:
 			break;
 		}
 		if (opts->flags & PARSE_OPT_COMP_ARG)

diff --git a/parse-options.h b/parse-options.h
index d931300f4d6..a1c7c86ad30 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -264,7 +264,7 @@ struct parse_opt_ctx_t {
 	const char **out;
 	int argc, cpidx, total;
 	const char *opt;
-	int flags;
+	enum parse_opt_flags flags;
 	const char *prefix;
 	const char **alias_groups; /* must be in groups of 3 elements! */
 	struct option *updated_options;

-- 
2.33.0.1340.ge9f77250f2b

Change the "flags" members of "struct option" to refer to their
corresponding "enum" defined earlier in the file.

The benefit of changing this to an enum isn't as great as with some
"enum parse_opt_type" as we'll always check this as a bitfield, so we
can't rely on the compiler checking "case" arms for us. But let's do
it for consistency with the rest of the file.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.h b/parse-options.h
index a1c7c86ad30..74b66ba6e93 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -134,7 +134,7 @@ struct option {
 	const char *argh;
 	const char *help;
 
-	int flags;
+	enum parse_opt_option_flags flags;
 	parse_opt_cb *callback;
 	intptr_t defval;
 	parse_opt_ll_cb *ll_callback;

-- 
2.33.0.1340.ge9f77250f2b

Stop using optname() in builtin/commit-graph.c to emit an error with
the --max-new-filters option. This changes code added in 809e0327f57
(builtin/commit-graph.c: introduce '--max-new-filters=<n>',
2020-09-18).

See 9440b831ad5 (parse-options: replace opterror() with optname(),
2018-11-10) for why using optname() like this is considered bad,
i.e. it's assembling human-readable output piecemeal, and the "option
`X'" at the start can't be translated.

It didn't matter in this case, but this code was also buggy in its use
of "opt->flags" to optname(), that function expects flags, but not
*those* flags.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 builtin/commit-graph.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 0386f5c7755..36552db89fe 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c

@@ -172,8 +172,7 @@ static int write_option_max_new_filters(const struct option *opt,
 		const char *s;
 		*to = strtol(arg, (char **)&s, 10);
 		if (*s)
-			return error(_("%s expects a numerical value"),
-				     optname(opt, opt->flags));
+			return error(_("option `max-new-filters' expects a numerical value"));
 	}
 	return 0;
 }

-- 
2.33.0.1340.ge9f77250f2b

In preparation for making "optname" a static function move it above
its first user in parse-options.c.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 733cbfa8821..238a283db5d 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -22,6 +22,21 @@ int optbug(const struct option *opt, const char *reason)
 	return error("BUG: switch '%c' %s", opt->short_name, reason);
 }
 
+const char *optname(const struct option *opt, int flags)
+{
+	static struct strbuf sb = STRBUF_INIT;
+
+	strbuf_reset(&sb);
+	if (flags & OPT_SHORT)
+		strbuf_addf(&sb, "switch `%c'", opt->short_name);
+	else if (flags & OPT_UNSET)
+		strbuf_addf(&sb, "option `no-%s'", opt->long_name);
+	else
+		strbuf_addf(&sb, "option `%s'", opt->long_name);
+
+	return sb.buf;
+}
+
 static enum parse_opt_result get_arg(struct parse_opt_ctx_t *p,
 				     const struct option *opt,
 				     int flags, const char **arg)

@@ -1037,18 +1052,3 @@ void NORETURN usage_msg_opt(const char *msg,
 	fprintf(stderr, "fatal: %s\n\n", msg);
 	usage_with_options(usagestr, options);
 }
-
-const char *optname(const struct option *opt, int flags)
-{
-	static struct strbuf sb = STRBUF_INIT;
-
-	strbuf_reset(&sb);
-	if (flags & OPT_SHORT)
-		strbuf_addf(&sb, "switch `%c'", opt->short_name);
-	else if (flags & OPT_UNSET)
-		strbuf_addf(&sb, "option `no-%s'", opt->long_name);
-	else
-		strbuf_addf(&sb, "option `%s'", opt->long_name);
-
-	return sb.buf;
-}

-- 
2.33.0.1340.ge9f77250f2b

Change these two functions to "static", the last user of "optname()"
outside of parse-options.c itself went away in the preceding commit,
for the reasons noted in 9440b831ad5 (parse-options: replace
opterror() with optname(), 2018-11-10) we shouldn't be adding any more
users of it.

The "optbug()" function was never used outside of parse-options.c, but
was made non-static in 1f275b7c4ca (parse-options: export opterr,
optbug, 2011-08-11). I think the only external user of optname() was
the commit-graph.c caller added in 09e0327f57 (builtin/commit-graph.c:
introduce '--max-new-filters=<n>', 2020-09-18).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 4 ++--
 parse-options.h | 3 ---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 238a283db5d..57e95846e83 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -11,7 +11,7 @@ static int disallow_abbreviated_options;
 #define OPT_SHORT 1
 #define OPT_UNSET 2
 
-int optbug(const struct option *opt, const char *reason)
+static int optbug(const struct option *opt, const char *reason)
 {
 	if (opt->long_name) {
 		if (opt->short_name)

@@ -22,7 +22,7 @@ int optbug(const struct option *opt, const char *reason)
 	return error("BUG: switch '%c' %s", opt->short_name, reason);
 }
 
-const char *optname(const struct option *opt, int flags)
+static const char *optname(const struct option *opt, int flags)
 {
 	static struct strbuf sb = STRBUF_INIT;
 

diff --git a/parse-options.h b/parse-options.h
index 74b66ba6e93..dd79c9c566f 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -224,9 +224,6 @@ NORETURN void usage_msg_opt(const char *msg,
 			    const char * const *usagestr,
 			    const struct option *options);
 
-int optbug(const struct option *opt, const char *reason);
-const char *optname(const struct option *opt, int flags);
-
 /*
  * Use these assertions for callbacks that expect to be called with NONEG and
  * NOARG respectively, and do not otherwise handle the "unset" and "arg"

-- 
2.33.0.1340.ge9f77250f2b

There were no tests for checking the specific output that we'll
generate in optname(), let's add some. That output was added back in
4a59fd13122 (Add a simple option parser., 2007-10-15).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 t/t0040-parse-options.sh | 42 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index da310ed29b1..d6f391a497b 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh

@@ -168,9 +168,45 @@ test_expect_success 'long options' '
 '
 
 test_expect_success 'missing required value' '
-	test_expect_code 129 test-tool parse-options -s &&
-	test_expect_code 129 test-tool parse-options --string &&
-	test_expect_code 129 test-tool parse-options --file
+	cat >expect <<-\EOF &&
+	error: switch `s'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options -s 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `string'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options --string 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `file'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options --file 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'superfluous value provided: boolean' '
+	cat >expect <<-\EOF &&
+	error: option `yes'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --yes=hi 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `no-yes'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --no-yes=hi 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'superfluous value provided: cmdmode' '
+	cat >expect <<-\EOF &&
+	error: option `mode1'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --mode1=hi 2>actual &&
+	test_cmp expect actual
 '
 
 cat >expect <<\EOF

-- 
2.33.0.1340.ge9f77250f2b

Change the comparisons against OPT_SHORT and OPT_UNSET to an enum
which keeps track of how a given option got parsed. The case of "0"
was an implicit OPT_LONG, so let's add an explicit label for it.

Due to the xor in 0f1930c5875 (parse-options: allow positivation of
options starting, with no-, 2012-02-25) the code already relied on
this being set back to 0. To avoid refactoring the logic involved in
that let's just start the enum at "0" instead of the usual "1<<0" (1),
but BUG() out if we don't have one of our expected flags.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 57e95846e83..1eb3b51f753 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -8,8 +8,11 @@
 
 static int disallow_abbreviated_options;
 
-#define OPT_SHORT 1
-#define OPT_UNSET 2
+enum opt_parsed {
+	OPT_LONG  = 0,
+	OPT_SHORT = 1<<0,
+	OPT_UNSET = 1<<1,
+};
 
 static int optbug(const struct option *opt, const char *reason)
 {

@@ -22,7 +25,7 @@ static int optbug(const struct option *opt, const char *reason)
 	return error("BUG: switch '%c' %s", opt->short_name, reason);
 }
 
-static const char *optname(const struct option *opt, int flags)
+static const char *optname(const struct option *opt, enum opt_parsed flags)
 {
 	static struct strbuf sb = STRBUF_INIT;
 

@@ -31,15 +34,17 @@ static const char *optname(const struct option *opt, int flags)
 		strbuf_addf(&sb, "switch `%c'", opt->short_name);
 	else if (flags & OPT_UNSET)
 		strbuf_addf(&sb, "option `no-%s'", opt->long_name);
-	else
+	else if (flags == OPT_LONG)
 		strbuf_addf(&sb, "option `%s'", opt->long_name);
+	else
+		BUG("optname() got unknown flags %d", flags);
 
 	return sb.buf;
 }
 
 static enum parse_opt_result get_arg(struct parse_opt_ctx_t *p,
 				     const struct option *opt,
-				     int flags, const char **arg)
+				     enum opt_parsed flags, const char **arg)
 {
 	if (p->opt) {
 		*arg = p->opt;

@@ -65,7 +70,7 @@ static void fix_filename(const char *prefix, const char **file)
 static enum parse_opt_result opt_command_mode_error(
 	const struct option *opt,
 	const struct option *all_opts,
-	int flags)
+	enum opt_parsed flags)
 {
 	const struct option *that;
 	struct strbuf that_name = STRBUF_INIT;

@@ -97,7 +102,7 @@ static enum parse_opt_result opt_command_mode_error(
 static enum parse_opt_result get_value(struct parse_opt_ctx_t *p,
 				       const struct option *opt,
 				       const struct option *all_opts,
-				       int flags)
+				       enum opt_parsed flags)
 {
 	const char *s, *arg;
 	const int unset = flags & OPT_UNSET;

@@ -318,11 +323,11 @@ static enum parse_opt_result parse_long_opt(
 	const struct option *all_opts = options;
 	const char *arg_end = strchrnul(arg, '=');
 	const struct option *abbrev_option = NULL, *ambiguous_option = NULL;
-	int abbrev_flags = 0, ambiguous_flags = 0;
+	enum opt_parsed abbrev_flags = OPT_LONG, ambiguous_flags = OPT_LONG;
 
 	for (; options->type != OPTION_END; options++) {
 		const char *rest, *long_name = options->long_name;
-		int flags = 0, opt_flags = 0;
+		enum opt_parsed flags = OPT_LONG, opt_flags = OPT_LONG;
 
 		if (!long_name)
 			continue;

-- 
2.33.0.1340.ge9f77250f2b

On Tue, Sep 28, 2021 at 03:14:28PM +0200, Ævar Arnfjörð Bjarmason wrote:

Stop using optname() in builtin/commit-graph.c to emit an error with
the --max-new-filters option. This changes code added in 809e0327f57
(builtin/commit-graph.c: introduce '--max-new-filters=<n>',
2020-09-18).

See 9440b831ad5 (parse-options: replace opterror() with optname(),
2018-11-10) for why using optname() like this is considered bad,
i.e. it's assembling human-readable output piecemeal, and the "option
`X'" at the start can't be translated.

In fact, using optname there (which blames to me) was a mistake for an
even simpler reason: there is no abbreviated form of
`--max-new-filters`, and we know that by the time this error is emitted
that we got the positive form instead of `--no-max-new-filters`.

So we could have just written the option's name verbatim, and given
translators something easier to work with.

Makes sense. The `'-style quoting is still weird to me. It is consistent
with some of the conversions in 9440b831ad5, but most importantly with
how parse-options.c:get_value() behaves (because it calls optname
underneath).

(This has nothing to do with your patch, but I thought the custom
write_option_max_new_filters callback was weird when I wrote it. It's
working around trying to make the negated form set a value to `-1`
instead of `0`. But it's an annoying hack, because we have to call
strtol() ourselves when we're not negated. *sigh*).

Looks good to me.

Thanks,
Taylor

On Wed, Sep 29 2021, Taylor Blau wrote:

On Tue, Sep 28, 2021 at 03:14:28PM +0200, Ævar Arnfjörð Bjarmason wrote:

quoted

Stop using optname() in builtin/commit-graph.c to emit an error with
the --max-new-filters option. This changes code added in 809e0327f57
(builtin/commit-graph.c: introduce '--max-new-filters=<n>',
2020-09-18).

See 9440b831ad5 (parse-options: replace opterror() with optname(),
2018-11-10) for why using optname() like this is considered bad,
i.e. it's assembling human-readable output piecemeal, and the "option
`X'" at the start can't be translated.

In fact, using optname there (which blames to me) was a mistake for an
even simpler reason: there is no abbreviated form of
`--max-new-filters`, and we know that by the time this error is emitted
that we got the positive form instead of `--no-max-new-filters`.

So we could have just written the option's name verbatim, and given
translators something easier to work with.

As an aside: Did you intend for this to work:

    git commit-graph write --max-new-filters=123 --no-max-new-filters

It's in the docstring, but then you're using OPT_CALLBACK_F(), but just
to set a flag of "0", so a OPT_CALLBACK() would do, along with a
PARSE_OPT_NONEG.

I'm about to re-roll this, but won't change that, but I think it
probably makes sense as a follow-on cleanuup.

I think you'd probably want a BUG_ON_OPT_NEG() instead for the "unset"
handling here. This seems like another case of mixing the state of
parse_options() with that of flags for the underlying API that we
discussed elsewhere either for this command or multi-pack-index. But
more on that below...

Also the usage if --no-* is wanted should not be:

    [--no-max-new-filters] [--max-new-filters <n>]

But is currently:

    [--[no-]max-new-filters <n>]

Which says the --no-* will take the <n>, but it won't.

quoted

It didn't matter in this case, but this code was also buggy in its use
of "opt->flags" to optname(), that function expects flags, but not
*those* flags.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 builtin/commit-graph.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 0386f5c7755..36552db89fe 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c

@@ -172,8 +172,7 @@ static int write_option_max_new_filters(const struct option *opt,
 		const char *s;
 		*to = strtol(arg, (char **)&s, 10);
 		if (*s)
-			return error(_("%s expects a numerical value"),
-				     optname(opt, opt->flags));
+			return error(_("option `max-new-filters' expects a numerical value"));

Makes sense. The `'-style quoting is still weird to me. It is consistent
with some of the conversions in 9440b831ad5, but most importantly with
how parse-options.c:get_value() behaves (because it calls optname
underneath).

Yeah I just reproduced the existing output here.

(This has nothing to do with your patch, but I thought the custom
write_option_max_new_filters callback was weird when I wrote it. It's
working around trying to make the negated form set a value to `-1`
instead of `0`. But it's an annoying hack, because we have to call
strtol() ourselves when we're not negated. *sigh*).

...on the "more on that below", looks like you intended that -1 handling
in some way, but I don't really see why yet, other than the "mixing the
state" I noted above.

I have some feature changes planned for parse-options.[ch], including
ones that allow us to delete some boilerplate (and sometimes buggy)
code in built-ins by having the API do heavier lifting.

In adding anything to the API I've found it hard to deal with it using
its own enums inconsistently, sometimes it's an "int", sometimes it's
the "enum", and having the "default" cases makes it hard to assert
that you've added things to all the right places.

This re-roll of the v1[1] should hopefully address all the feedback on
that version, particularly the motivation for the enum-as-bitfield
labeling, as expanded on in 02/11.

1. http://lore.kernel.org/git/cover-00.10-00000000000-20210928T130905Z-avarab@gmail.com

Ævar Arnfjörð Bjarmason (11):
  parse-options.h: move PARSE_OPT_SHELL_EVAL between enums
  parse-options.[ch]: consistently use "enum parse_opt_flags"
  parse-options.[ch]: consistently use "enum parse_opt_result"
  parse-options.c: use exhaustive "case" arms for "enum
    parse_opt_result"
  parse-options.c: use exhaustive "case" arms for "enum parse_opt_type"
  parse-options.h: make the "flags" in "struct option" an enum
  parse-options.c: move optname() earlier in the file
  commit-graph: stop using optname()
  parse-options.[ch]: make opt{bug,name}() "static"
  parse-options tests: test optname() output
  parse-options: change OPT_{SHORT,UNSET} to an enum

 builtin/blame.c          |   3 +
 builtin/commit-graph.c   |   3 +-
 builtin/shortlog.c       |   3 +
 parse-options.c          | 135 ++++++++++++++++++++++++++-------------
 parse-options.h          |  26 ++++----
 t/t0040-parse-options.sh |  42 +++++++++++-
 6 files changed, 151 insertions(+), 61 deletions(-)

Range-diff against v1:
 1:  19d1573a4e0 =  1:  553931702df parse-options.h: move PARSE_OPT_SHELL_EVAL between enums
 2:  289bb437eb5 !  2:  99f5251c557 parse-options.[ch]: consistently use "enum parse_opt_flags"
    @@ Commit message
         parse-options.[ch]: consistently use "enum parse_opt_flags"
     
         Use the "enum parse_opt_flags" instead of an "int flags" as arguments
    -    to the various functions in parse-options.c. This will help to catch
    -    cases where we're not handling cases in switch statements, and
    -    generally make it obvious which "flags" we're referring to in this
    -    case.
    +    to the various functions in parse-options.c.
    +
    +    In C enums aren't first-class types, and the "enum
    +    parse_opt_option_flag" uses a enum-as-bitfield pattern. So unlike
    +    exhaustively enumerated "case" arms we're not going to get validation
    +    that we used the "right" enum labels.
    +
    +    I.e. this won't catch the sort of bug that was fixed with
    +    "PARSE_OPT_SHELL_EVAL" in the preceding commit.
    +
    +    But there's still a benefit to doing this when it comes to the wider C
    +    ecosystem. E.g. the GNU debugger (gdb) will helpfully detect and print
    +    out meaningful enum labels in this case. Here's the output before and
    +    after when breaking in "parse_options()" after invoking "git stash
    +    show":
    +
    +    Before:
    +
    +        (gdb) p flags
    +        $1 = 9
    +
    +    After:
    +
    +        (gdb) p flags
    +        $1 = (PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_UNKNOWN)
    +
    +    Of course as noted in[1] there's a limit to this smartness,
    +    i.e. manually setting it with unrelated enum labels won't be
    +    caught. There are some third-party extensions to do more exhaustive
    +    checking[2], perhaps we'll be able to make use of them sooner than
    +    later.
    +
    +    We've also got prior art using this pattern in the codebase. See
    +    e.g. "enum bloom_filter_computed" added in 312cff52074 (bloom: split
    +    'get_bloom_filter()' in two, 2020-09-16) and the "permitted" enum
    +    added in ce910287e72 (add -p: fix checking of user input, 2020-08-17).
    +
    +    1. https://lore.kernel.org/git/87mtnvvj3c.fsf@evledraar.gmail.com/
    +    2. https://github.com/sinelaw/elfs-clang-plugins/blob/master/enums_conversion/README.md
     
         Signed-off-by: Ævar Arnfjörð Bjarmason [off-list ref]
     
    @@ parse-options.c: int parse_options_end(struct parse_opt_ctx_t *ctx)
      {
      	struct parse_opt_ctx_t ctx;
      	struct option *real_options;
    -@@ parse-options.c: int parse_options(int argc, const char **argv, const char *prefix,
    - 	case PARSE_OPT_NON_OPTION:
    - 	case PARSE_OPT_DONE:
    - 		break;
    --	default: /* PARSE_OPT_UNKNOWN */
    -+	case PARSE_OPT_UNKNOWN:
    - 		if (ctx.argv[0][1] == '-') {
    - 			error(_("unknown option `%s'"), ctx.argv[0] + 2);
    - 		} else if (isascii(*ctx.opt)) {
     
      ## parse-options.h ##
     @@ parse-options.h: struct option {
 3:  fbcbaa47329 !  3:  be198e42df9 parse-options.[ch]: consistently use "enum parse_opt_result"
    @@ Commit message
         third caller in 309be813c9b (update-index: migrate to parse-options
         API, 2010-12-01) was already checking for these.
     
    +    As can be seen when trying to sort through the deluge of warnings
    +    produced when compiling this with CC=g++ (mostly unrelated to this
    +    change) we're not consistently using "enum parse_opt_result" even now,
    +    i.e. we'll return error() and "return 0;". See f41179f16ba
    +    (parse-options: avoid magic return codes, 2019-01-27) for a commit
    +    which started changing some of that.
    +
    +    I'm not doing any more of that exhaustive migration here, and it's
    +    probably not worthwhile past the point of being able to check "enum
    +    parse_opt_result" in switch().
    +
         Signed-off-by: Ævar Arnfjörð Bjarmason [off-list ref]
     
      ## builtin/blame.c ##
    @@ builtin/shortlog.c: int cmd_shortlog(int argc, const char **argv, const char *pr
      			exit(129);
     
      ## parse-options.c ##
    -@@ parse-options.c: static int usage_with_options_internal(struct parse_opt_ctx_t *,
    - 				       const char * const *,
    - 				       const struct option *, int, int);
    +@@ parse-options.c: static void free_preprocessed_options(struct option *options)
    + 	free(options);
    + }
      
    +-static int usage_with_options_internal(struct parse_opt_ctx_t *,
    +-				       const char * const *,
    +-				       const struct option *, int, int);
    +-
     -int parse_options_step(struct parse_opt_ctx_t *ctx,
     -		       const struct option *options,
     -		       const char * const usagestr[])
    ++static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t *,
    ++							 const char * const *,
    ++							 const struct option *,
    ++							 int, int);
    ++
     +enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
     +					 const struct option *options,
     +					 const char * const usagestr[])
    @@ parse-options.c: int parse_options_end(struct parse_opt_ctx_t *ctx)
      {
      	struct parse_opt_ctx_t ctx;
      	struct option *real_options;
    +@@ parse-options.c: static int usage_argh(const struct option *opts, FILE *outfile)
    + #define USAGE_OPTS_WIDTH 24
    + #define USAGE_GAP         2
    + 
    +-static int usage_with_options_internal(struct parse_opt_ctx_t *ctx,
    +-				       const char * const *usagestr,
    +-				       const struct option *opts, int full, int err)
    ++static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t *ctx,
    ++							 const char * const *usagestr,
    ++							 const struct option *opts,
    ++							 int full, int err)
    + {
    + 	FILE *outfile = err ? stderr : stdout;
    + 	int need_newline;
     
      ## parse-options.h ##
     @@ parse-options.h: struct option {
 -:  ----------- >  4:  a253db7a60d parse-options.c: use exhaustive "case" arms for "enum parse_opt_result"
 4:  624a19000e1 !  5:  467828780d0 parse-options.c: use exhaustive "case" arms for "enum parse_opt_type"
    @@ Commit message
         handling of options it's probably not worth it to get there, but let's
         match its ordering where it's easy to do so.
     
    +    There was a discussion about whether this was worth the added
    +    verbosity, as argued in[1] I think it's worth it for getting
    +    compile-time checking when adding new option types. We *should* have
    +    tests for some of these, but e.g. in the show_gitcomp() case one might
    +    run through the whole test suite and only hit a missing case at the
    +    end on the completion tests.
    +
    +    This technically changes the handling of OPTION_END, but it's
    +    obviously the right thing to do. We're calling this code from within a
    +    loop that uses OPTION_END as a break condition, so it was never caught
    +    by the "default" case.
    +
    +    So let's make encountering OPTION_END a BUG(), just like it already is
    +    in the get_value() handling added in 4a59fd13122 (Add a simple option
    +    parser., 2007-10-15).
    +
    +    1. https://lore.kernel.org/git/87tui3vk8y.fsf@evledraar.gmail.com/
    +
         Signed-off-by: Ævar Arnfjörð Bjarmason [off-list ref]
     
      ## parse-options.c ##
    @@ parse-options.c: static enum parse_opt_result get_value(struct parse_opt_ctx_t *
      }
      
      static enum parse_opt_result parse_short_opt(struct parse_opt_ctx_t *p,
    +@@ parse-options.c: static void parse_options_check(const struct option *opts)
    + 			err |= optbug(opts, "uses feature "
    + 					"not supported for dashless options");
    + 		switch (opts->type) {
    ++		case OPTION_END:
    ++			BUG("unreachable");
    ++
    + 		case OPTION_COUNTUP:
    + 		case OPTION_BIT:
    + 		case OPTION_NEGBIT:
     @@ parse-options.c: static void parse_options_check(const struct option *opts)
      			BUG("OPT_ALIAS() should not remain at this point. "
      			    "Are you using parse_options_step() directly?\n"
    @@ parse-options.c: static void parse_options_check(const struct option *opts)
     -			; /* ok. (usually accepts an argument) */
     +
     +		case OPTION_BITOP:
    -+		case OPTION_END:
     +		case OPTION_FILENAME:
     +		case OPTION_GROUP:
     +		case OPTION_INTEGER:
    @@ parse-options.c: static void parse_options_check(const struct option *opts)
      		}
      		if (opts->argh &&
      		    strcspn(opts->argh, " _") != strlen(opts->argh))
    +@@ parse-options.c: static void show_negated_gitcomp(const struct option *opts, int show_all,
    + 			continue;
    + 
    + 		switch (opts->type) {
    ++		case OPTION_END:
    ++			BUG("unreachable");
    ++
    + 		case OPTION_STRING:
    + 		case OPTION_FILENAME:
    + 		case OPTION_INTEGER:
     @@ parse-options.c: static void show_negated_gitcomp(const struct option *opts, int show_all,
      		case OPTION_SET_INT:
      			has_unset_form = 1;
      			break;
     -		default:
     +		/* special types */
    -+		case OPTION_END:
     +		case OPTION_GROUP:
     +		case OPTION_NUMBER:
     +		case OPTION_ALIAS:
    @@ parse-options.c: static void show_negated_gitcomp(const struct option *opts, int
      			break;
      		}
      		if (!has_unset_form)
    +@@ parse-options.c: static int show_gitcomp(const struct option *opts, int show_all)
    + 			continue;
    + 
    + 		switch (opts->type) {
    ++		case OPTION_END:
    ++			BUG("unreachable");
    + 		case OPTION_GROUP:
    + 			continue;
    + 		case OPTION_STRING:
     @@ parse-options.c: static int show_gitcomp(const struct option *opts, int show_all)
      				break;
      			suffix = "=";
      			break;
     -		default:
     +		/* special types */
    -+		case OPTION_END:
     +		case OPTION_NUMBER:
     +		case OPTION_ALIAS:
     +
 5:  697e432c012 =  6:  34669327550 parse-options.h: make the "flags" in "struct option" an enum
 6:  c065f7d7362 =  7:  e82a4e477d5 parse-options.c: move optname() earlier in the file
 7:  b0b313795c7 =  8:  58683b3d89d commit-graph: stop using optname()
 8:  07ba0e6f995 =  9:  8cbee660174 parse-options.[ch]: make opt{bug,name}() "static"
 9:  ce508fddc8f = 10:  f727f683eb1 parse-options tests: test optname() output
10:  a28ab961125 = 11:  4fbc07fc7fd parse-options: change OPT_{SHORT,UNSET} to an enum
-- 
2.33.0.1374.gc8f4fa74caf

Fix a bad landmine of a bug which has been with us ever since
PARSE_OPT_SHELL_EVAL was added in 47e9cd28f8a (parseopt: wrap
rev-parse --parseopt usage for eval consumption, 2010-06-12).

It's an argument to parse_options() and should therefore be in "enum
parse_opt_flags", but it was added to the per-option "enum
parse_opt_option_flags" by mistake.

Therefore as soon as we'd have an enum member in the former that
reached its value of "1 << 8" we'd run into a seemingly bizarre bug
where that new option would turn on the unrelated PARSE_OPT_SHELL_EVAL
in "git rev-parse --parseopt" by proxy.

I manually checked that no other enum members suffered from such
overlap, by setting the values to non-overlapping values, and making
the relevant codepaths BUG() out if the given value was above/below
the expected (excluding flags=0 in the case of "enum
parse_opt_flags").

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.h b/parse-options.h
index 39d90882548..3a3176ae65c 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -33,6 +33,7 @@ enum parse_opt_flags {
 	PARSE_OPT_KEEP_UNKNOWN = 1 << 3,
 	PARSE_OPT_NO_INTERNAL_HELP = 1 << 4,
 	PARSE_OPT_ONE_SHOT = 1 << 5,
+	PARSE_OPT_SHELL_EVAL = 1 << 6,
 };
 
 enum parse_opt_option_flags {

@@ -44,7 +45,6 @@ enum parse_opt_option_flags {
 	PARSE_OPT_NODASH = 1 << 5,
 	PARSE_OPT_LITERAL_ARGHELP = 1 << 6,
 	PARSE_OPT_FROM_ALIAS = 1 << 7,
-	PARSE_OPT_SHELL_EVAL = 1 << 8,
 	PARSE_OPT_NOCOMPLETE = 1 << 9,
 	PARSE_OPT_COMP_ARG = 1 << 10,
 	PARSE_OPT_CMDMODE = 1 << 11,

-- 
2.33.0.1374.gc8f4fa74caf

Use the "enum parse_opt_flags" instead of an "int flags" as arguments
to the various functions in parse-options.c.

In C enums aren't first-class types, and the "enum
parse_opt_option_flag" uses a enum-as-bitfield pattern. So unlike
exhaustively enumerated "case" arms we're not going to get validation
that we used the "right" enum labels.

I.e. this won't catch the sort of bug that was fixed with
"PARSE_OPT_SHELL_EVAL" in the preceding commit.

But there's still a benefit to doing this when it comes to the wider C
ecosystem. E.g. the GNU debugger (gdb) will helpfully detect and print
out meaningful enum labels in this case. Here's the output before and
after when breaking in "parse_options()" after invoking "git stash
show":

Before:

    (gdb) p flags
    $1 = 9

After:

    (gdb) p flags
    $1 = (PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_UNKNOWN)

Of course as noted in[1] there's a limit to this smartness,
i.e. manually setting it with unrelated enum labels won't be
caught. There are some third-party extensions to do more exhaustive
checking[2], perhaps we'll be able to make use of them sooner than
later.

We've also got prior art using this pattern in the codebase. See
e.g. "enum bloom_filter_computed" added in 312cff52074 (bloom: split
'get_bloom_filter()' in two, 2020-09-16) and the "permitted" enum
added in ce910287e72 (add -p: fix checking of user input, 2020-08-17).

1. https://lore.kernel.org/git/87mtnvvj3c.fsf@evledraar.gmail.com/
2. https://github.com/sinelaw/elfs-clang-plugins/blob/master/enums_conversion/README.md

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 11 +++++++----
 parse-options.h |  6 ++++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 55c5821b08d..9c8ba963400 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -481,7 +481,8 @@ static void parse_options_check(const struct option *opts)
 
 static void parse_options_start_1(struct parse_opt_ctx_t *ctx,
 				  int argc, const char **argv, const char *prefix,
-				  const struct option *options, int flags)
+				  const struct option *options,
+				  enum parse_opt_flags flags)
 {
 	ctx->argc = argc;
 	ctx->argv = argv;

@@ -506,7 +507,8 @@ static void parse_options_start_1(struct parse_opt_ctx_t *ctx,
 
 void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 int argc, const char **argv, const char *prefix,
-			 const struct option *options, int flags)
+			 const struct option *options,
+			 enum parse_opt_flags flags)
 {
 	memset(ctx, 0, sizeof(*ctx));
 	parse_options_start_1(ctx, argc, argv, prefix, options, flags);

@@ -838,8 +840,9 @@ int parse_options_end(struct parse_opt_ctx_t *ctx)
 }
 
 int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options, const char * const usagestr[],
-		  int flags)
+		  const struct option *options,
+		  const char * const usagestr[],
+		  enum parse_opt_flags flags)
 {
 	struct parse_opt_ctx_t ctx;
 	struct option *real_options;

diff --git a/parse-options.h b/parse-options.h
index 3a3176ae65c..fb5aafd4f7b 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -213,7 +213,8 @@ struct option {
  */
 int parse_options(int argc, const char **argv, const char *prefix,
 		  const struct option *options,
-		  const char * const usagestr[], int flags);
+		  const char * const usagestr[],
+		  enum parse_opt_flags flags);
 
 NORETURN void usage_with_options(const char * const *usagestr,
 				 const struct option *options);

@@ -270,7 +271,8 @@ struct parse_opt_ctx_t {
 
 void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 int argc, const char **argv, const char *prefix,
-			 const struct option *options, int flags);
+			 const struct option *options,
+			 enum parse_opt_flags flags);
 
 int parse_options_step(struct parse_opt_ctx_t *ctx,
 		       const struct option *options,

-- 
2.33.0.1374.gc8f4fa74caf

Use the "enum parse_opt_result" instead of an "int flags" as the
return value of the applicable functions in parse-options.c.

This will help catch future bugs, such as the missing "case" arms in
the two existing users of the API in "blame.c" and "shortlog.c". A
third caller in 309be813c9b (update-index: migrate to parse-options
API, 2010-12-01) was already checking for these.

As can be seen when trying to sort through the deluge of warnings
produced when compiling this with CC=g++ (mostly unrelated to this
change) we're not consistently using "enum parse_opt_result" even now,
i.e. we'll return error() and "return 0;". See f41179f16ba
(parse-options: avoid magic return codes, 2019-01-27) for a commit
which started changing some of that.

I'm not doing any more of that exhaustive migration here, and it's
probably not worthwhile past the point of being able to check "enum
parse_opt_result" in switch().

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 builtin/blame.c    |  3 +++
 builtin/shortlog.c |  3 +++
 parse-options.c    | 31 +++++++++++++++++--------------
 parse-options.h    | 15 ++++++++-------
 4 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/builtin/blame.c b/builtin/blame.c
index 641523ff9af..9273fb222d5 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c

@@ -917,6 +917,9 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 			    PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_ARGV0);
 	for (;;) {
 		switch (parse_options_step(&ctx, options, blame_opt_usage)) {
+		case PARSE_OPT_NON_OPTION:
+		case PARSE_OPT_UNKNOWN:
+			break;
 		case PARSE_OPT_HELP:
 		case PARSE_OPT_ERROR:
 			exit(129);

diff --git a/builtin/shortlog.c b/builtin/shortlog.c
index 3e7ab1ca821..e7f7af5de3f 100644
--- a/builtin/shortlog.c
+++ b/builtin/shortlog.c

@@ -374,6 +374,9 @@ int cmd_shortlog(int argc, const char **argv, const char *prefix)
 
 	for (;;) {
 		switch (parse_options_step(&ctx, options, shortlog_usage)) {
+		case PARSE_OPT_NON_OPTION:
+		case PARSE_OPT_UNKNOWN:
+			break;
 		case PARSE_OPT_HELP:
 		case PARSE_OPT_ERROR:
 			exit(129);

diff --git a/parse-options.c b/parse-options.c
index 9c8ba963400..f718242096c 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -699,13 +699,14 @@ static void free_preprocessed_options(struct option *options)
 	free(options);
 }
 
-static int usage_with_options_internal(struct parse_opt_ctx_t *,
-				       const char * const *,
-				       const struct option *, int, int);
-
-int parse_options_step(struct parse_opt_ctx_t *ctx,
-		       const struct option *options,
-		       const char * const usagestr[])
+static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t *,
+							 const char * const *,
+							 const struct option *,
+							 int, int);
+
+enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
+					 const struct option *options,
+					 const char * const usagestr[])
 {
 	int internal_help = !(ctx->flags & PARSE_OPT_NO_INTERNAL_HELP);
 

@@ -839,10 +840,11 @@ int parse_options_end(struct parse_opt_ctx_t *ctx)
 	return ctx->cpidx + ctx->argc;
 }
 
-int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options,
-		  const char * const usagestr[],
-		  enum parse_opt_flags flags)
+enum parse_opt_result parse_options(int argc, const char **argv,
+				    const char *prefix,
+				    const struct option *options,
+				    const char * const usagestr[],
+				    enum parse_opt_flags flags)
 {
 	struct parse_opt_ctx_t ctx;
 	struct option *real_options;

@@ -900,9 +902,10 @@ static int usage_argh(const struct option *opts, FILE *outfile)
 #define USAGE_OPTS_WIDTH 24
 #define USAGE_GAP         2
 
-static int usage_with_options_internal(struct parse_opt_ctx_t *ctx,
-				       const char * const *usagestr,
-				       const struct option *opts, int full, int err)
+static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t *ctx,
+							 const char * const *usagestr,
+							 const struct option *opts,
+							 int full, int err)
 {
 	FILE *outfile = err ? stderr : stdout;
 	int need_newline;

diff --git a/parse-options.h b/parse-options.h
index fb5aafd4f7b..d931300f4d6 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -211,10 +211,11 @@ struct option {
  * untouched and parse_options() returns the number of options
  * processed.
  */
-int parse_options(int argc, const char **argv, const char *prefix,
-		  const struct option *options,
-		  const char * const usagestr[],
-		  enum parse_opt_flags flags);
+enum parse_opt_result parse_options(int argc, const char **argv,
+				    const char *prefix,
+				    const struct option *options,
+				    const char * const usagestr[],
+				    enum parse_opt_flags flags);
 
 NORETURN void usage_with_options(const char * const *usagestr,
 				 const struct option *options);

@@ -274,9 +275,9 @@ void parse_options_start(struct parse_opt_ctx_t *ctx,
 			 const struct option *options,
 			 enum parse_opt_flags flags);
 
-int parse_options_step(struct parse_opt_ctx_t *ctx,
-		       const struct option *options,
-		       const char * const usagestr[]);
+enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
+					 const struct option *options,
+					 const char * const usagestr[]);
 
 int parse_options_end(struct parse_opt_ctx_t *ctx);
 

-- 
2.33.0.1374.gc8f4fa74caf

Change the "default" case in parse_options() that handles the return
value of parse_options_step() to simply have a "case" arm for
PARSE_OPT_UNKNOWN, instead of leaving it to a comment. This means the
compiler can warn us about any missing case arms.

This adjusts code added in ff43ec3e2d2 (parse-opt: create
parse_options_step., 2008-06-23), given its age it may pre-date the
existence (or widespread use) of this coding style, which we've since
adopted more widely.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.c b/parse-options.c
index f718242096c..e33700d6e71 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -866,7 +866,7 @@ enum parse_opt_result parse_options(int argc, const char **argv,
 	case PARSE_OPT_NON_OPTION:
 	case PARSE_OPT_DONE:
 		break;
-	default: /* PARSE_OPT_UNKNOWN */
+	case PARSE_OPT_UNKNOWN:
 		if (ctx.argv[0][1] == '-') {
 			error(_("unknown option `%s'"), ctx.argv[0] + 2);
 		} else if (isascii(*ctx.opt)) {

-- 
2.33.0.1374.gc8f4fa74caf

Change code in get_value(), parse_options_check() etc. to do away with
the "default" case in favor of exhaustively checking the relevant
fields.

The added "return -1" is needed for the GCC version commented on
inline, my local clang 11.0.1-2 does not require it. Let's add it for
now to appease GCC.

The added "special types" etc. comments correspond to the relevant
comments and ordering on the "enum parse_opt_type". Let's try to keep
the same order and commentary as there where possible for
clarity. This doesn't reach that end-state, and due to the different
handling of options it's probably not worth it to get there, but let's
match its ordering where it's easy to do so.

There was a discussion about whether this was worth the added
verbosity, as argued in[1] I think it's worth it for getting
compile-time checking when adding new option types. We *should* have
tests for some of these, but e.g. in the show_gitcomp() case one might
run through the whole test suite and only hit a missing case at the
end on the completion tests.

This technically changes the handling of OPTION_END, but it's
obviously the right thing to do. We're calling this code from within a
loop that uses OPTION_END as a break condition, so it was never caught
by the "default" case.

So let's make encountering OPTION_END a BUG(), just like it already is
in the get_value() handling added in 4a59fd13122 (Add a simple option
parser., 2007-10-15).

1. https://lore.kernel.org/git/87tui3vk8y.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 48 +++++++++++++++++++++++++++++++++++++++++++-----
 parse-options.h |  2 +-
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index e33700d6e71..dedd40efec5 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -219,9 +219,14 @@ static enum parse_opt_result get_value(struct parse_opt_ctx_t *p,
 				     optname(opt, flags));
 		return 0;
 
-	default:
+	/* special types */
+	case OPTION_END:
+	case OPTION_GROUP:
+	case OPTION_NUMBER:
+	case OPTION_ALIAS:
 		BUG("opt->type %d should not happen", opt->type);
 	}
+	return -1; /* gcc 10.2.1-6's -Werror=return-type */
 }
 
 static enum parse_opt_result parse_short_opt(struct parse_opt_ctx_t *p,

@@ -443,6 +448,9 @@ static void parse_options_check(const struct option *opts)
 			err |= optbug(opts, "uses feature "
 					"not supported for dashless options");
 		switch (opts->type) {
+		case OPTION_END:
+			BUG("unreachable");
+
 		case OPTION_COUNTUP:
 		case OPTION_BIT:
 		case OPTION_NEGBIT:

@@ -468,8 +476,14 @@ static void parse_options_check(const struct option *opts)
 			BUG("OPT_ALIAS() should not remain at this point. "
 			    "Are you using parse_options_step() directly?\n"
 			    "That case is not supported yet.");
-		default:
-			; /* ok. (usually accepts an argument) */
+
+		case OPTION_BITOP:
+		case OPTION_FILENAME:
+		case OPTION_GROUP:
+		case OPTION_INTEGER:
+		case OPTION_MAGNITUDE:
+		case OPTION_STRING:
+			break;
 		}
 		if (opts->argh &&
 		    strcspn(opts->argh, " _") != strlen(opts->argh))

@@ -532,6 +546,9 @@ static void show_negated_gitcomp(const struct option *opts, int show_all,
 			continue;
 
 		switch (opts->type) {
+		case OPTION_END:
+			BUG("unreachable");
+
 		case OPTION_STRING:
 		case OPTION_FILENAME:
 		case OPTION_INTEGER:

@@ -543,7 +560,14 @@ static void show_negated_gitcomp(const struct option *opts, int show_all,
 		case OPTION_SET_INT:
 			has_unset_form = 1;
 			break;
-		default:
+		/* special types */
+		case OPTION_GROUP:
+		case OPTION_NUMBER:
+		case OPTION_ALIAS:
+		/* options with no arguments */
+		case OPTION_BITOP:
+		/* options with arguments (usually) */
+		case OPTION_LOWLEVEL_CALLBACK:
 			break;
 		}
 		if (!has_unset_form)

@@ -578,6 +602,8 @@ static int show_gitcomp(const struct option *opts, int show_all)
 			continue;
 
 		switch (opts->type) {
+		case OPTION_END:
+			BUG("unreachable");
 		case OPTION_GROUP:
 			continue;
 		case OPTION_STRING:

@@ -593,7 +619,19 @@ static int show_gitcomp(const struct option *opts, int show_all)
 				break;
 			suffix = "=";
 			break;
-		default:
+		/* special types */
+		case OPTION_NUMBER:
+		case OPTION_ALIAS:
+
+		/* options with no arguments */
+		case OPTION_BIT:
+		case OPTION_NEGBIT:
+		case OPTION_BITOP:
+		case OPTION_COUNTUP:
+		case OPTION_SET_INT:
+
+		/* options with arguments (usually) */
+		case OPTION_LOWLEVEL_CALLBACK:
 			break;
 		}
 		if (opts->flags & PARSE_OPT_COMP_ARG)

diff --git a/parse-options.h b/parse-options.h
index d931300f4d6..a1c7c86ad30 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -264,7 +264,7 @@ struct parse_opt_ctx_t {
 	const char **out;
 	int argc, cpidx, total;
 	const char *opt;
-	int flags;
+	enum parse_opt_flags flags;
 	const char *prefix;
 	const char **alias_groups; /* must be in groups of 3 elements! */
 	struct option *updated_options;

-- 
2.33.0.1374.gc8f4fa74caf

Change the "flags" members of "struct option" to refer to their
corresponding "enum" defined earlier in the file.

The benefit of changing this to an enum isn't as great as with some
"enum parse_opt_type" as we'll always check this as a bitfield, so we
can't rely on the compiler checking "case" arms for us. But let's do
it for consistency with the rest of the file.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.h b/parse-options.h
index a1c7c86ad30..74b66ba6e93 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -134,7 +134,7 @@ struct option {
 	const char *argh;
 	const char *help;
 
-	int flags;
+	enum parse_opt_option_flags flags;
 	parse_opt_cb *callback;
 	intptr_t defval;
 	parse_opt_ll_cb *ll_callback;

-- 
2.33.0.1374.gc8f4fa74caf

In preparation for making "optname" a static function move it above
its first user in parse-options.c.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index dedd40efec5..2cf6f4d01c1 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -22,6 +22,21 @@ int optbug(const struct option *opt, const char *reason)
 	return error("BUG: switch '%c' %s", opt->short_name, reason);
 }
 
+const char *optname(const struct option *opt, int flags)
+{
+	static struct strbuf sb = STRBUF_INIT;
+
+	strbuf_reset(&sb);
+	if (flags & OPT_SHORT)
+		strbuf_addf(&sb, "switch `%c'", opt->short_name);
+	else if (flags & OPT_UNSET)
+		strbuf_addf(&sb, "option `no-%s'", opt->long_name);
+	else
+		strbuf_addf(&sb, "option `%s'", opt->long_name);
+
+	return sb.buf;
+}
+
 static enum parse_opt_result get_arg(struct parse_opt_ctx_t *p,
 				     const struct option *opt,
 				     int flags, const char **arg)

@@ -1044,18 +1059,3 @@ void NORETURN usage_msg_opt(const char *msg,
 	fprintf(stderr, "fatal: %s\n\n", msg);
 	usage_with_options(usagestr, options);
 }
-
-const char *optname(const struct option *opt, int flags)
-{
-	static struct strbuf sb = STRBUF_INIT;
-
-	strbuf_reset(&sb);
-	if (flags & OPT_SHORT)
-		strbuf_addf(&sb, "switch `%c'", opt->short_name);
-	else if (flags & OPT_UNSET)
-		strbuf_addf(&sb, "option `no-%s'", opt->long_name);
-	else
-		strbuf_addf(&sb, "option `%s'", opt->long_name);
-
-	return sb.buf;
-}

-- 
2.33.0.1374.gc8f4fa74caf

Stop using optname() in builtin/commit-graph.c to emit an error with
the --max-new-filters option. This changes code added in 809e0327f57
(builtin/commit-graph.c: introduce '--max-new-filters=<n>',
2020-09-18).

See 9440b831ad5 (parse-options: replace opterror() with optname(),
2018-11-10) for why using optname() like this is considered bad,
i.e. it's assembling human-readable output piecemeal, and the "option
`X'" at the start can't be translated.

It didn't matter in this case, but this code was also buggy in its use
of "opt->flags" to optname(), that function expects flags, but not
*those* flags.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 builtin/commit-graph.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 0386f5c7755..36552db89fe 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c

@@ -172,8 +172,7 @@ static int write_option_max_new_filters(const struct option *opt,
 		const char *s;
 		*to = strtol(arg, (char **)&s, 10);
 		if (*s)
-			return error(_("%s expects a numerical value"),
-				     optname(opt, opt->flags));
+			return error(_("option `max-new-filters' expects a numerical value"));
 	}
 	return 0;
 }

-- 
2.33.0.1374.gc8f4fa74caf

Change these two functions to "static", the last user of "optname()"
outside of parse-options.c itself went away in the preceding commit,
for the reasons noted in 9440b831ad5 (parse-options: replace
opterror() with optname(), 2018-11-10) we shouldn't be adding any more
users of it.

The "optbug()" function was never used outside of parse-options.c, but
was made non-static in 1f275b7c4ca (parse-options: export opterr,
optbug, 2011-08-11). I think the only external user of optname() was
the commit-graph.c caller added in 09e0327f57 (builtin/commit-graph.c:
introduce '--max-new-filters=<n>', 2020-09-18).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 parse-options.c | 4 ++--
 parse-options.h | 3 ---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 2cf6f4d01c1..0239c6bd418 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -11,7 +11,7 @@ static int disallow_abbreviated_options;
 #define OPT_SHORT 1
 #define OPT_UNSET 2
 
-int optbug(const struct option *opt, const char *reason)
+static int optbug(const struct option *opt, const char *reason)
 {
 	if (opt->long_name) {
 		if (opt->short_name)

@@ -22,7 +22,7 @@ int optbug(const struct option *opt, const char *reason)
 	return error("BUG: switch '%c' %s", opt->short_name, reason);
 }
 
-const char *optname(const struct option *opt, int flags)
+static const char *optname(const struct option *opt, int flags)
 {
 	static struct strbuf sb = STRBUF_INIT;
 

diff --git a/parse-options.h b/parse-options.h
index 74b66ba6e93..dd79c9c566f 100644
--- a/parse-options.h
+++ b/parse-options.h

@@ -224,9 +224,6 @@ NORETURN void usage_msg_opt(const char *msg,
 			    const char * const *usagestr,
 			    const struct option *options);
 
-int optbug(const struct option *opt, const char *reason);
-const char *optname(const struct option *opt, int flags);
-
 /*
  * Use these assertions for callbacks that expect to be called with NONEG and
  * NOARG respectively, and do not otherwise handle the "unset" and "arg"

-- 
2.33.0.1374.gc8f4fa74caf

There were no tests for checking the specific output that we'll
generate in optname(), let's add some. That output was added back in
4a59fd13122 (Add a simple option parser., 2007-10-15).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 t/t0040-parse-options.sh | 42 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index da310ed29b1..d6f391a497b 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh

@@ -168,9 +168,45 @@ test_expect_success 'long options' '
 '
 
 test_expect_success 'missing required value' '
-	test_expect_code 129 test-tool parse-options -s &&
-	test_expect_code 129 test-tool parse-options --string &&
-	test_expect_code 129 test-tool parse-options --file
+	cat >expect <<-\EOF &&
+	error: switch `s'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options -s 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `string'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options --string 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `file'\'' requires a value
+	EOF
+	test_expect_code 129 test-tool parse-options --file 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'superfluous value provided: boolean' '
+	cat >expect <<-\EOF &&
+	error: option `yes'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --yes=hi 2>actual &&
+	test_cmp expect actual &&
+
+	cat >expect <<-\EOF &&
+	error: option `no-yes'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --no-yes=hi 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'superfluous value provided: cmdmode' '
+	cat >expect <<-\EOF &&
+	error: option `mode1'\'' takes no value
+	EOF
+	test_expect_code 129 test-tool parse-options --mode1=hi 2>actual &&
+	test_cmp expect actual
 '
 
 cat >expect <<\EOF