Merge branch 'jk/log-follow-with-non-literal-pathspec'

"git [-c log.follow=true] log [--follow] ':(glob)f**'" used to barf.

* jk/log-follow-with-non-literal-pathspec:
  diff: detect pathspec magic not supported by --follow
  diff: factor out --follow pathspec check
  pathspec: factor out magic-to-name function

builtin/log.c

@@ -866,7 +866,7 @@ static void log_setup_revisions_tweak(struct rev_info *rev,
 				      struct setup_revision_opt *opt)
 {
 	if (rev->diffopt.flags.default_follow_renames &&
-	    rev->prune_data.nr == 1)
+	    diff_check_follow_pathspec(&rev->prune_data, 0))
 		rev->diffopt.flags.follow_renames = 1;
 
 	if (rev->first_parent_only)

diff.c

@@ -4751,6 +4751,31 @@ unsigned diff_filter_bit(char status)
 	return filter_bit[(int) status];
 }
 
+int diff_check_follow_pathspec(struct pathspec *ps, int die_on_error)
+{
+	unsigned forbidden_magic;
+
+	if (ps->nr != 1) {
+		if (die_on_error)
+			die(_("--follow requires exactly one pathspec"));
+		return 0;
+	}
+
+	forbidden_magic = ps->items[0].magic & ~(PATHSPEC_FROMTOP |
+						 PATHSPEC_LITERAL);
+	if (forbidden_magic) {
+		if (die_on_error) {
+			struct strbuf sb = STRBUF_INIT;
+			pathspec_magic_names(forbidden_magic, &sb);
+			die(_("pathspec magic not supported by --follow: %s"),
+			    sb.buf);
+		}
+		return 0;
+	}
+
+	return 1;
+}
+
 void diff_setup_done(struct diff_options *options)
 {
 	unsigned check_mask = DIFF_FORMAT_NAME |
@@ -4858,8 +4883,8 @@ void diff_setup_done(struct diff_options *options)
 
 	options->diff_path_counter = 0;
 
-	if (options->flags.follow_renames && options->pathspec.nr != 1)
+	if (options->flags.follow_renames)
-		die(_("--follow requires exactly one pathspec"));
+		diff_check_follow_pathspec(&options->pathspec, 1);
 
 	if (!options->use_color || external_diff())
 		options->color_moved = 0;

diff.h

@@ -539,6 +539,13 @@ void repo_diff_setup(struct repository *, struct diff_options *);
 struct option *add_diff_options(const struct option *, struct diff_options *);
 int diff_opt_parse(struct diff_options *, const char **, int, const char *);
 void diff_setup_done(struct diff_options *);
+
+/*
+ * Returns true if the pathspec can work with --follow mode. If die_on_error is
+ * set, die() with a specific error message rather than returning false.
+ */
+int diff_check_follow_pathspec(struct pathspec *ps, int die_on_error);
+
 int git_config_rename(const char *var, const char *value);
 
 #define DIFF_DETECT_RENAME	1

pathspec.c

@@ -531,24 +531,29 @@ static int pathspec_item_cmp(const void *a_, const void *b_)
 	return strcmp(a->match, b->match);
 }
 
-static void NORETURN unsupported_magic(const char *pattern,
+void pathspec_magic_names(unsigned magic, struct strbuf *out)
-				       unsigned magic)
 {
-	struct strbuf sb = STRBUF_INIT;
 	int i;
 	for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
 		const struct pathspec_magic *m = pathspec_magic + i;
 		if (!(magic & m->bit))
 			continue;
-		if (sb.len)
+		if (out->len)
-			strbuf_addstr(&sb, ", ");
+			strbuf_addstr(out, ", ");
 
 		if (m->mnemonic)
-			strbuf_addf(&sb, _("'%s' (mnemonic: '%c')"),
+			strbuf_addf(out, _("'%s' (mnemonic: '%c')"),
 				    m->name, m->mnemonic);
 		else
-			strbuf_addf(&sb, "'%s'", m->name);
+			strbuf_addf(out, "'%s'", m->name);
 	}
+}
+
+static void NORETURN unsupported_magic(const char *pattern,
+				       unsigned magic)
+{
+	struct strbuf sb = STRBUF_INIT;
+	pathspec_magic_names(magic, &sb);
 	/*
 	 * We may want to substitute "this command" with a command
 	 * name. E.g. when "git add -p" or "git add -i" dies when running

pathspec.h

@@ -130,6 +130,14 @@ void parse_pathspec_file(struct pathspec *pathspec,
 void copy_pathspec(struct pathspec *dst, const struct pathspec *src);
 void clear_pathspec(struct pathspec *);
 
+/*
+ * Add a human-readable string to "out" representing the PATHSPEC_* flags set
+ * in "magic". The result is suitable for error messages, but not for
+ * parsing as pathspec magic itself (you get 'icase' with quotes, not
+ * :(icase)).
+ */
+void pathspec_magic_names(unsigned magic, struct strbuf *out);
+
 static inline int ps_strncmp(const struct pathspec_item *item,
 			     const char *s1, const char *s2, size_t n)
 {

t/t4202-log.sh

@@ -187,6 +187,21 @@ test_expect_success 'git config log.follow does not die with no paths' '
 	git log --
 '
 
+test_expect_success 'git log --follow rejects unsupported pathspec magic' '
+	test_must_fail git log --follow ":(top,glob,icase)ichi" 2>stderr &&
+	# check full error message; we want to be sure we mention both
+	# of the rejected types (glob,icase), but not the allowed one (top)
+	echo "fatal: pathspec magic not supported by --follow: ${SQ}glob${SQ}, ${SQ}icase${SQ}" >expect &&
+	test_cmp expect stderr
+'
+
+test_expect_success 'log.follow disabled with unsupported pathspec magic' '
+	test_config log.follow true &&
+	git log --format=%s ":(glob,icase)ichi" >actual &&
+	echo third >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'git config log.follow is overridden by --no-follow' '
 	test_config log.follow true &&
 	git log --no-follow --pretty="format:%s" ichi >actual &&