[PATCH v2 06/16] environment: store comment_line_char as a string

[Jeff King <peff@peff.net>]

We'd like to eventually support multi-byte comment prefixes, but the
comment_line_char variable is referenced in many spots, making the
transition difficult.

Let's start by storing the character in a NUL-terminated string. That
will let us switch code over incrementally to the string format, and we
can easily support the existing code with a macro wrapper (since we'll
continue to allow only a single-byte prefix, this will behave
identically).

Once all references to the "char" variable have been converted, we can
drop it and enable longer strings.

We'll still have to touch all of the spots that create or set the
variable in this patch, but there are only a few (reading the config,
and the "auto" character selector).

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/commit.c | 4 ++--
 config.c         | 2 +-
 environment.c    | 2 +-
 environment.h    | 3 ++-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index b2d05c0cc9..82229c3100 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -686,7 +686,7 @@ static void adjust_comment_line_char(const struct strbuf *sb)
 	const char *p;
 
 	if (!memchr(sb->buf, candidates[0], sb->len)) {
-		comment_line_char = candidates[0];
+		comment_line_str = xstrfmt("%c", candidates[0]);
 		return;
 	}
 
@@ -707,7 +707,7 @@ static void adjust_comment_line_char(const struct strbuf *sb)
 	if (!*p)
 		die(_("unable to select a comment character that is not used\n"
 		      "in the current commit message"));
-	comment_line_char = *p;
+	comment_line_str = xstrfmt("%c", *p);
 }
 
 static void prepare_amend_commit(struct commit *commit, struct strbuf *sb,
diff --git a/config.c b/config.c
index f561631374..7e5dbca4bd 100644
--- a/config.c
+++ b/config.c
@@ -1568,7 +1568,7 @@ static int git_default_core_config(const char *var, const char *value,
 		else if (value[0] && !value[1]) {
 			if (value[0] == '\n')
 				return error(_("core.commentChar cannot be newline"));
-			comment_line_char = value[0];
+			comment_line_str = xstrfmt("%c", value[0]);
 			auto_comment_line_char = 0;
 		} else
 			return error(_("core.commentChar should only be one ASCII character"));
diff --git a/environment.c b/environment.c
index 60706ea398..a73ba9c12c 100644
--- a/environment.c
+++ b/environment.c
@@ -110,7 +110,7 @@ int protect_ntfs = PROTECT_NTFS_DEFAULT;
  * The character that begins a commented line in user-editable file
  * that is subject to stripspace.
  */
-char comment_line_char = '#';
+const char *comment_line_str = "#";
 int auto_comment_line_char;
 
 /* Parallel index stat data preload? */
diff --git a/environment.h b/environment.h
index 5cec19cecc..1c7d0c2f74 100644
--- a/environment.h
+++ b/environment.h
@@ -8,7 +8,8 @@ struct strvec;
  * The character that begins a commented line in user-editable file
  * that is subject to stripspace.
  */
-extern char comment_line_char;
+#define comment_line_char (comment_line_str[0])
+extern const char *comment_line_str;
 extern int auto_comment_line_char;
 
 /*
-- 
2.44.0.481.gf1a6d20963