[gdb/testsuite] Fix gdb.dwarf2/gdb-add-index-symlink.exp

The test-case gdb.dwarf2/gdb-add-index-symlink.exp interpretes a failure to
add an index as a failure to add an index for a symlink:
...
if { [ensure_gdb_index $symlink] == -1 } {
    fail "Unable to call gdb-add-index with a symlink to a symfile"
    return -1
}
...

However, it's possible that the gdb-add-index also fails with a regular
file.  Add a check for that situation.

Tested on x86_64-linux.

1 files changed, 13 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.dwarf2/gdb-add-index-symlink.exp b/gdb/testsuite/gdb.dwarf2/gdb-add-index-symlink.exp
index eaeddec..74c558a 100644
--- a/gdb/testsuite/gdb.dwarf2/gdb-add-index-symlink.exp
+++ b/gdb/testsuite/gdb.dwarf2/gdb-add-index-symlink.exp
@@ -22,6 +22,19 @@ if {![dwarf2_support]} {
 
 standard_testfile main.c
 
+# First check whether we can actually handle the non-symlink case.
+with_test_prefix non-symlink {
+    if { [prepare_for_testing "failed to prepare" "${testfile}" \
+	      [list ${srcfile}]] } {
+	return -1
+    }
+
+    if { [ensure_gdb_index $binfile] == -1 } {
+	return -1
+    }
+}
+
+# Regenerate exec without index.
 if { [prepare_for_testing "failed to prepare" "${testfile}" \
 	  [list ${srcfile}]] } {
     return -1