Merge branch 'jc/pretty-lf'

Conflicts:
	pretty.c
	t/t6006-rev-list-format.sh

Documentation/pretty-formats.txt

@@ -144,6 +144,14 @@ insert an empty string unless we are traversing reflog entries (e.g., by
 `git log -g`). The `%d` placeholder will use the "short" decoration
 format if `--decorate` was not already provided on the command line.
 
+If you add a `{plus}` (plus sign) after '%' of a placeholder, a line-feed
+is inserted immediately before the expansion if and only if the
+placeholder expands to a non-empty string.
+
+If you add a `-` (minus sign) after '%' of a placeholder, line-feeds that
+immediately precede the expansion are deleted if and only if the
+placeholder expands to an empty string.
+
 * 'tformat:'
 +
 The 'tformat:' format works exactly like 'format:', except that it

pretty.c

@@ -628,8 +628,8 @@ static void rewrap_message_tail(struct strbuf *sb,
 	c->indent2 = new_indent2;
 }
 
-static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
-                               void *context)
+static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
+				void *context)
 {
 	struct format_commit_context *c = context;
 	const struct commit *commit = c->commit;
@@ -816,6 +816,44 @@ static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
 	return 0;	/* unknown placeholder */
 }
 
+static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
+				 void *context)
+{
+	int consumed;
+	size_t orig_len;
+	enum {
+		NO_MAGIC,
+		ADD_LF_BEFORE_NON_EMPTY,
+		DEL_LF_BEFORE_EMPTY,
+	} magic = NO_MAGIC;
+
+	switch (placeholder[0]) {
+	case '-':
+		magic = DEL_LF_BEFORE_EMPTY;
+		break;
+	case '+':
+		magic = ADD_LF_BEFORE_NON_EMPTY;
+		break;
+	default:
+		break;
+	}
+	if (magic != NO_MAGIC)
+		placeholder++;
+
+	orig_len = sb->len;
+	consumed = format_commit_one(sb, placeholder, context);
+	if (magic == NO_MAGIC)
+		return consumed;
+
+	if ((orig_len == sb->len) && magic == DEL_LF_BEFORE_EMPTY) {
+		while (sb->len && sb->buf[sb->len - 1] == '\n')
+			strbuf_setlen(sb, sb->len - 1);
+	} else if ((orig_len != sb->len) && magic == ADD_LF_BEFORE_NON_EMPTY) {
+		strbuf_insert(sb, orig_len, "\n", 1);
+	}
+	return consumed + 1;
+}
+
 void format_commit_message(const struct commit *commit,
 			   const char *format, struct strbuf *sb,
 			   const struct pretty_print_context *pretty_ctx)

t/t6006-rev-list-format.sh

@@ -162,6 +162,28 @@ test_expect_success 'empty email' '
 	}
 '
 
+test_expect_success 'del LF before empty (1)' '
+	git show -s --pretty=format:"%s%n%-b%nThanks%n" HEAD^^ >actual &&
+	test $(wc -l <actual) = 2
+'
+
+test_expect_success 'del LF before empty (2)' '
+	git show -s --pretty=format:"%s%n%-b%nThanks%n" HEAD >actual &&
+	test $(wc -l <actual) = 6 &&
+	grep "^$" actual
+'
+
+test_expect_success 'add LF before non-empty (1)' '
+	git show -s --pretty=format:"%s%+b%nThanks%n" HEAD^^ >actual &&
+	test $(wc -l <actual) = 2
+'
+
+test_expect_success 'add LF before non-empty (2)' '
+	git show -s --pretty=format:"%s%+b%nThanks%n" HEAD >actual &&
+	test $(wc -l <actual) = 6 &&
+	grep "^$" actual
+'
+
 test_expect_success '"%h %gD: %gs" is same as git-reflog' '
 	git reflog >expect &&
 	git log -g --format="%h %gD: %gs" >actual &&