[gdb/build] Fix unused var in dwarf2/read.c

On x86_64-linux, with gcc 7.5.0 I ran into a build breaker:
...
gdb/dwarf2/read.c: In function ‘void read_comp_units_from_section()’:
gdb/dwarf2/read.c:4297:31: error: unused variable ‘sig_type_it’ \
  [-Werror=unused-variable]
    auto [sig_type_it, inserted] = sig_types.emplace (sig_ptr);
                               ^
...

Fix this by dropping the unused variable.

Tested on x86_64-linux, by completing a build.

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index e044d1eb0e4de2d274e2f1023650eb9c65b5a1c4..b4fd7e30cb7c46803b5a118c8a751e8c2933a17b 100644 (file)
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -4294,7 +4294,7 @@ read_comp_units_from_section (dwarf2_per_objfile *per_objfile,
          sig_type->type_offset_in_tu = cu_header.type_cu_offset_in_tu;
          this_cu.reset (sig_type.release ());
 
-         auto [sig_type_it, inserted] = sig_types.emplace (sig_ptr);
+         auto inserted = sig_types.emplace (sig_ptr).second;
 
          if (!inserted)
            complaint (_("debug type entry at offset %s is duplicate to"