[binutils-gdb] gdb/dwarf: fix build error with older gcc

[Simon Marchi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=07caff21f90c2f0c9b7b0e79b00b774be668594c

commit 07caff21f90c2f0c9b7b0e79b00b774be668594c
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date:   Sun Mar 15 20:12:22 2026 -0400

    gdb/dwarf: fix build error with older gcc
    
    With gcc 7.5.0, we get:
    
          CXX    dwarf2/read.o
        /home/simark/src/binutils-gdb/gdb/dwarf2/read.c: In function ‘void decode_line_header_for_cu(die_info*, dwarf2_cu*, const file_and_directory&)’:
        /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:5796:25: error: unused variable ‘_’ [-Werror=unused-variable]
               auto [_, inserted_]
                                 ^
    
    That version of gcc (and earlier) apparently produces unused variable
    warnings for unused structured bindings.  Fix it by accessing `.second`
    directly to get the "inserted" boolean value.
    
    Change-Id: I6e78c8c317623f3d830fef8d043f85ff789133d4
    Bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81767

Diff:
---
 gdb/dwarf2/read.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 31c44476d2c..e41f06890d7 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -5793,9 +5793,8 @@ decode_line_header_for_cu (struct die_info *die, struct dwarf2_cu *cu,
 
   if (per_objfile->line_headers.has_value ())
     {
-      auto [_, inserted_]
-	= per_objfile->line_headers->try_emplace (sao, cu->line_header);
-      inserted = inserted_;
+      inserted
+	= per_objfile->line_headers->try_emplace (sao, cu->line_header).second;
 
       if (inserted)
 	{