[PATCH] [gdb/build] Fix unused var in corelow.c

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

On x86_64-linux, with gcc 7.5.0 and CFLAGS/CXXFLAGS="-O0 -g -Wall" I ran into
a build breaker:
...
gdb/corelow.c: In member function ‘void mapped_file_info::add(const char*, const char*, const char*, std::vector<mem_range>&&, const bfd_build_id*)’:
gdb/corelow.c:1822:27: error: unused variable ‘it’ [-Werror=unused-variable]
   const auto [it, inserted]
                           ^
...

Fix this by dropping the variable it.

Tested on x86_64-linux.
---
 gdb/corelow.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gdb/corelow.c b/gdb/corelow.c
index 16f07c23faa..ab2fa746de8 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -1819,8 +1819,8 @@ mapped_file_info::add (const char *soname,
      parsed, we group the build-id information based on the file name.  As
      a consequence, we should see each EXPECTED_FILENAME value exactly
      once.  This means that each insertion should always succeed.  */
-  const auto [it, inserted]
-    = m_filename_to_build_id_map.emplace (expected_filename, build_id);
+  const auto inserted
+    = m_filename_to_build_id_map.emplace (expected_filename, build_id).second;
   gdb_assert (inserted);
 
   /* Setup the reverse build-id to file name map.  */

base-commit: 29c70787112e01cd52b53bf14bdcacb0a11e0725
-- 
2.35.3