[PATCH] t/test_lib: avoid naked bash arrays in file_lineno

["Carlo Marcelo Arenas Belón" <carenas@gmail.com>]

662f9cf154 (tests: when run in Bash, annotate test failures with file
name/line number, 2020-04-11), introduces a way to report the location
(file:lineno) of a failed test case by traversing the bash callstack.

The implementation requires bash and is therefore protected by a guard
but NetBSD sh will still have to parse the function and therefore will
result in:

  ** t0000-basic.sh ***
  ./test-lib.sh: 681: Syntax error: Bad substitution

Enclose the bash specific code inside an eval to avoid parsing errors
and while at it, simplify the logic so that instead of traversing the
callstack just pop the two topmost entries that are required.

Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
---
 t/test-lib.sh | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 1b221951a8..60b8e70678 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -677,14 +677,13 @@ die () {
 
 file_lineno () {
 	test -z "$GIT_TEST_FRAMEWORK_SELFTEST" && test -n "$BASH" || return 0
-	local i
-	for i in ${!BASH_SOURCE[*]}
-	do
-		case $i,"${BASH_SOURCE[$i]##*/}" in
-		0,t[0-9]*.sh) echo "t/${BASH_SOURCE[$i]}:$LINENO: ${1+$1: }"; return;;
-		*,t[0-9]*.sh) echo "t/${BASH_SOURCE[$i]}:${BASH_LINENO[$(($i-1))]}: ${1+$1: }"; return;;
-		esac
-	done
+	eval '
+		local n=$(echo ${#BASH_SOURCE[*]})
+		if test $n -ge 2
+		then
+			echo "${BASH_SOURCE[$n - 1]}:${BASH_LINENO[$n - 2]}: $1: "
+		fi
+	'
 }
 
 GIT_EXIT_OK=
-- 
2.26.2.686.gfaf46a9ccd