[RFC 1/4] ref-filter: start adding strbufs with errors

[Olga Telezhnaya <olyatelezhnaya@gmail.com>]

This is a first step in removing any printing from
ref-filter formatting logic, so that it could be more general.
Everything would be the same for show_ref_array_item() users.
But, if you want to deal with errors by your own, you could invoke
format_ref_array_item(). It means that you need to print everything
(the result and errors) on your side.

This commit changes signature of format_ref_array_item() by adding
return value and strbuf parameter for errors, and fixes
its callers.

Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
---
 builtin/branch.c |  7 +++++--
 ref-filter.c     | 17 ++++++++++++-----
 ref-filter.h     |  7 ++++---
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/builtin/branch.c b/builtin/branch.c
index 8dcc2ed058be6..f86709ca42d5e 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -391,7 +391,6 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
 	struct ref_array array;
 	int maxwidth = 0;
 	const char *remote_prefix = "";
-	struct strbuf out = STRBUF_INIT;
 	char *to_free = NULL;
 
 	/*
@@ -419,7 +418,10 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
 	ref_array_sort(sorting, &array);
 
 	for (i = 0; i < array.nr; i++) {
-		format_ref_array_item(array.items[i], format, &out);
+		struct strbuf out = STRBUF_INIT;
+		struct strbuf err = STRBUF_INIT;
+		if (format_ref_array_item(array.items[i], format, &out, &err))
+			die("%s", err.buf);
 		if (column_active(colopts)) {
 			assert(!filter->verbose && "--column and --verbose are incompatible");
 			 /* format to a string_list to let print_columns() do its job */
@@ -428,6 +430,7 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
 			fwrite(out.buf, 1, out.len, stdout);
 			putchar('\n');
 		}
+		strbuf_release(&err);
 		strbuf_release(&out);
 	}
 
diff --git a/ref-filter.c b/ref-filter.c
index 45fc56216aaa8..54fae00bdd410 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -2118,9 +2118,10 @@ static void append_literal(const char *cp, const char *ep, struct ref_formatting
 	}
 }
 
-void format_ref_array_item(struct ref_array_item *info,
+int format_ref_array_item(struct ref_array_item *info,
 			   const struct ref_format *format,
-			   struct strbuf *final_buf)
+			   struct strbuf *final_buf,
+			   struct strbuf *error_buf)
 {
 	const char *cp, *sp, *ep;
 	struct ref_formatting_state state = REF_FORMATTING_STATE_INIT;
@@ -2148,19 +2149,25 @@ void format_ref_array_item(struct ref_array_item *info,
 		resetv.s = GIT_COLOR_RESET;
 		append_atom(&resetv, &state);
 	}
-	if (state.stack->prev)
-		die(_("format: %%(end) atom missing"));
+	if (state.stack->prev) {
+		strbuf_addstr(error_buf, _("format: %(end) atom missing"));
+		return -1;
+	}
 	strbuf_addbuf(final_buf, &state.stack->output);
 	pop_stack_element(&state.stack);
+	return 0;
 }
 
 void show_ref_array_item(struct ref_array_item *info,
 			 const struct ref_format *format)
 {
 	struct strbuf final_buf = STRBUF_INIT;
+	struct strbuf error_buf = STRBUF_INIT;
 
-	format_ref_array_item(info, format, &final_buf);
+	if (format_ref_array_item(info, format, &final_buf, &error_buf))
+		die("%s", error_buf.buf);
 	fwrite(final_buf.buf, 1, final_buf.len, stdout);
+	strbuf_release(&error_buf);
 	strbuf_release(&final_buf);
 	putchar('\n');
 }
diff --git a/ref-filter.h b/ref-filter.h
index 0d98342b34319..e13f8e6f8721a 100644
--- a/ref-filter.h
+++ b/ref-filter.h
@@ -110,9 +110,10 @@ int verify_ref_format(struct ref_format *format);
 /*  Sort the given ref_array as per the ref_sorting provided */
 void ref_array_sort(struct ref_sorting *sort, struct ref_array *array);
 /*  Based on the given format and quote_style, fill the strbuf */
-void format_ref_array_item(struct ref_array_item *info,
-			   const struct ref_format *format,
-			   struct strbuf *final_buf);
+int format_ref_array_item(struct ref_array_item *info,
+			  const struct ref_format *format,
+			  struct strbuf *final_buf,
+			  struct strbuf *error_buf);
 /*  Print the ref using the given format and quote_style */
 void show_ref_array_item(struct ref_array_item *info, const struct ref_format *format);
 /*  Parse a single sort specifier and add it to the list */

--
https://github.com/git/git/pull/466