gdb: add string_file::release method

A common pattern for string_file is to want to move out the internal
string buffer, because it is the result of the computation that we want
to return.  It is the reason why string_file::string returns a non-const
reference, as explained in the comment.  I think it would make sense to
have a dedicated method for that instead and make string_file::string
return a const reference.

This allows removing the explicit std::move in the typical case.  Note
that compile_program::compute was missing a move, meaning that the
resulting string was copied.  With the new version, it's not possible to
forget to move.

Change-Id: Ieaefa35b73daa7930b2f3a26988b6e3b4121bb79

1 files changed, 2 insertions, 4 deletions

diff --git a/gdb/tui/tui-disasm.c b/gdb/tui/tui-disasm.c
index f40d4e2..445503a 100644
--- a/gdb/tui/tui-disasm.c
+++ b/gdb/tui/tui-disasm.c
@@ -130,14 +130,12 @@ tui_disassemble (struct gdbarch *gdbarch,
 	}
 
       /* Capture the disassembled instruction.  */
-      tal.insn = std::move (gdb_dis_out.string ());
-      gdb_dis_out.clear ();
+      tal.insn = gdb_dis_out.release ();
 
       /* And capture the address the instruction is at.  */
       tal.addr = orig_pc;
       print_address (gdbarch, orig_pc, &gdb_dis_out);
-      tal.addr_string = std::move (gdb_dis_out.string ());
-      gdb_dis_out.clear ();
+      tal.addr_string = std::move (gdb_dis_out.release ());
 
       if (addr_size != nullptr)
 	{