[pushed] [gdb/build] Fix Wunused-variable in selftests::test_enumerate

[Tom de Vries <tdevries@suse.de>]

On openSUSE Leap 15.6, with gcc 7.5.0, I ran into:
...
enumerate-selftests.c: In function 'void selftests::test_enumerate()':
enumerate-selftests.c:85:22: error: \
  unused variable 'i' [-Werror=unused-variable]
     for (auto [i, val] : gdb::ranges::views::enumerate (vec))
                      ^
cc1plus: all warnings being treated as errors
...

Fix this by checking the value of i.

Tested on x86_64-linux.
---
 gdb/unittests/enumerate-selftests.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/unittests/enumerate-selftests.c b/gdb/unittests/enumerate-selftests.c
index ddda29f6625..4ca85277fec 100644
--- a/gdb/unittests/enumerate-selftests.c
+++ b/gdb/unittests/enumerate-selftests.c
@@ -81,11 +81,17 @@ test_enumerate ()
   {
     std::vector<int> vec = { 1, 2, 3 };
     std::vector<int> expected = { 10, 20, 30 };
+    std::vector<int> actual_i;
+    std::vector<int> expected_i = { 0, 1, 2 };
 
     for (auto [i, val] : gdb::ranges::views::enumerate (vec))
-      val *= 10;
+      {
+	val *= 10;
+	actual_i.push_back (i);
+      }
 
     SELF_CHECK (vec == expected);
+    SELF_CHECK (actual_i == expected_i);
   }
 
   /* Test enumeration over an empty container.  */

base-commit: f2e83582f4f1c6374afdd919fed59d713a225c0e
-- 
2.51.0