[RFC/PATCH] i18n of multi-line messages

[Junio C Hamano <gitster@pobox.com>]

Advice messages are by definition meant for human end-users, and prime
candidates for i18n/l10n. They tend to also be more verbose to be helpful,
and need to be longer than just one line.

Although we do not have parameterized multi-line advice messages yet, once
we do, we cannot emit such a message like this:

	advise(_("Please rename %s to something else"), gostak);
        advise(_("so that we can avoid distimming %s unnecessarily."), doshes);

because some translations may need to have the replacement of 'gostak' on
the second line (or 'doshes' on the first line). Some languages may even
need to use three lines in order to fit the same message within a
reasonable width.

Instead, it has to be a single advise() construct, like this:

	advise(_("Please rename %s to something else\n"
                 "so that we can avoid distimming %s unnecessarily."),
		gostak, doshes); 

Update the advise() function and its existing callers to

 - take a format string that can be multi-line and translatable as a
   whole;
 - use the string and the parameters to form a localized message; and
 - append each line in the result to localization of the "hint: " prefix.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 advice.c         |   23 ++++++++++++++++-------
 builtin/revert.c |    9 ++++-----
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/advice.c b/advice.c
index e02e632..fcdf66a 100644
--- a/advice.c
+++ b/advice.c
@@ -21,11 +21,21 @@ static struct {
 
 void advise(const char *advice, ...)
 {
+	struct strbuf buf = STRBUF_INIT;
 	va_list params;
+	const char *cp, *np;
 
 	va_start(params, advice);
-	vreportf("hint: ", advice, params);
+	strbuf_addf(&buf, advice, params);
 	va_end(params);
+
+	for (cp = buf.buf; *cp; cp = np) {
+		np = strchrnul(cp, '\n');
+		fprintf(stderr, "%s%.*s\n", _("hint: "), (int)(np - cp), cp);
+		if (*np)
+			np++;
+	}
+	strbuf_release(&buf);
 }
 
 int git_default_advice_config(const char *var, const char *value)
@@ -46,16 +56,15 @@ int git_default_advice_config(const char *var, const char *value)
 int error_resolve_conflict(const char *me)
 {
 	error("'%s' is not possible because you have unmerged files.", me);
-	if (advice_resolve_conflict) {
+	if (advice_resolve_conflict)
 		/*
 		 * Message used both when 'git commit' fails and when
 		 * other commands doing a merge do.
 		 */
-		advise("Fix them up in the work tree,");
-		advise("and then use 'git add/rm <file>' as");
-		advise("appropriate to mark resolution and make a commit,");
-		advise("or use 'git commit -a'.");
-	}
+		advise(_("Fix them up in the work tree,\n"
+			 "and then use 'git add/rm <file>' as\n"
+			 "appropriate to mark resolution and make a commit,\n"
+			 "or use 'git commit -a'."));
 	return -1;
 }
 
diff --git a/builtin/revert.c b/builtin/revert.c
index fce3f92..440d2be 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -343,11 +343,10 @@ static void print_advice(int show_hint)
 		return;
 	}
 
-	if (show_hint) {
-		advise("after resolving the conflicts, mark the corrected paths");
-		advise("with 'git add <paths>' or 'git rm <paths>'");
-		advise("and commit the result with 'git commit'");
-	}
+	if (show_hint)
+		advise(_("after resolving the conflicts, mark the corrected paths\n"
+			 "with 'git add <paths>' or 'git rm <paths>'\n"
+			 "and commit the result with 'git commit'"));
 }
 
 static void write_message(struct strbuf *msgbuf, const char *filename)