line-range: reject -L line numbers less than 1

Since inception, git-blame -L has been documented as accepting 1-based
line numbers. When handed a line number less than 1, -L's behavior is
undocumented and undefined; it's also nonsensical and should be
diagnosed as an error. Do so.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

line-range.c

@@ -54,8 +54,11 @@ static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
 	}
 	num = strtol(spec, &term, 10);
 	if (term != spec) {
-		if (ret)
+		if (ret) {
+			if (num <= 0)
+				die("-L invalid line number: %ld", num);
 			*ret = num;
+		}
 		return term;
 	}
 

t/annotate-tests.sh

@@ -185,15 +185,15 @@ test_expect_success 'blame -L Y,X (undocumented)' '
 	check_count -L6,3 B 1 B1 1 B2 1 D 1
 '
 
-test_expect_failure 'blame -L -X' '
+test_expect_success 'blame -L -X' '
 	test_must_fail $PROG -L-1 file
 '
 
-test_expect_failure 'blame -L 0' '
+test_expect_success 'blame -L 0' '
 	test_must_fail $PROG -L0 file
 '
 
-test_expect_failure 'blame -L ,0' '
+test_expect_success 'blame -L ,0' '
 	test_must_fail $PROG -L,0 file
 '
 
@@ -447,8 +447,8 @@ test_expect_success 'blame empty' '
 	check_count -h HEAD^^ -f incremental
 '
 
-test_expect_success 'blame -L 0 empty (undocumented)' '
-	check_count -h HEAD^^ -f incremental -L0
+test_expect_success 'blame -L 0 empty' '
+	test_must_fail $PROG -L0 incremental HEAD^^
 '
 
 test_expect_success 'blame -L 1 empty' '
@@ -463,8 +463,8 @@ test_expect_success 'blame half' '
 	check_count -h HEAD^ -f incremental I 1
 '
 
-test_expect_success 'blame -L 0 half (undocumented)' '
-	check_count -h HEAD^ -f incremental -L0 I 1
+test_expect_success 'blame -L 0 half' '
+	test_must_fail $PROG -L0 incremental HEAD^
 '
 
 test_expect_success 'blame -L 1 half' '
@@ -483,8 +483,8 @@ test_expect_success 'blame full' '
 	check_count -f incremental I 1
 '
 
-test_expect_success 'blame -L 0 full (undocumented)' '
-	check_count -f incremental -L0 I 1
+test_expect_success 'blame -L 0 full' '
+	test_must_fail $PROG -L0 incremental
 '
 
 test_expect_success 'blame -L 1 full' '