gdb: Replace gdb::optional with std::optional

Since GDB now requires C++17, we don't need the internally maintained
gdb::optional implementation.  This patch does the following replacing:
  - gdb::optional -> std::optional
  - gdb::in_place -> std::in_place
  - #include "gdbsupport/gdb_optional.h" -> #include <optional>

This change has mostly been done automatically.  One exception is
gdbsupport/thread-pool.* which did not use the gdb:: prefix as it
already lives in the gdb namespace.

Change-Id: I19a92fa03e89637bab136c72e34fd351524f65e9
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>

3 files changed, 9 insertions, 9 deletions

diff --git a/gdb/nat/linux-osdata.c b/gdb/nat/linux-osdata.c
index 103b7ab..e853846 100644
--- a/gdb/nat/linux-osdata.c
+++ b/gdb/nat/linux-osdata.c
@@ -66,7 +66,7 @@ linux_common_core_of_thread (ptid_t ptid)
   sprintf (filename, "/proc/%lld/task/%lld/stat",
 	   (PID_T) ptid.pid (), (PID_T) ptid.lwp ());
 
-  gdb::optional<std::string> content = read_text_file_to_string (filename);
+  std::optional<std::string> content = read_text_file_to_string (filename);
   if (!content.has_value ())
     return -1;
 
@@ -257,10 +257,10 @@ get_cores_used_by_process (PID_T pid, int *cores, const int num_cores)
 
 /* get_core_array_size helper that uses /sys/devices/system/cpu/possible.  */
 
-static gdb::optional<size_t>
+static std::optional<size_t>
 get_core_array_size_using_sys_possible ()
 {
-  gdb::optional<std::string> possible
+  std::optional<std::string> possible
     = read_text_file_to_string ("/sys/devices/system/cpu/possible");
 
   if (!possible.has_value ())
@@ -310,7 +310,7 @@ get_core_array_size ()
      we are in a container that has access to a subset of the host's cores.
      It will return a size that considers all the CPU cores available to the
      host.  If that fails for some reason, fall back to sysconf.  */
-  gdb::optional<size_t> count = get_core_array_size_using_sys_possible ();
+  std::optional<size_t> count = get_core_array_size_using_sys_possible ();
   if (count.has_value ())
     return *count;
 
diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c
index 8028494..bf4c438 100644
--- a/gdb/nat/windows-nat.c
+++ b/gdb/nat/windows-nat.c
@@ -698,10 +698,10 @@ windows_process_info::matching_pending_stop (bool debug_events)
 
 /* See nat/windows-nat.h.  */
 
-gdb::optional<pending_stop>
+std::optional<pending_stop>
 windows_process_info::fetch_pending_stop (bool debug_events)
 {
-  gdb::optional<pending_stop> result;
+  std::optional<pending_stop> result;
   for (auto iter = pending_stops.begin ();
        iter != pending_stops.end ();
        ++iter)
@@ -818,7 +818,7 @@ create_process_wrapper (FUNC *do_create_process, const CHAR *image,
 	  InitializeProcThreadAttributeList (info_ex.lpAttributeList,
 					     1, 0, &size);
 
-	  gdb::optional<BOOL> return_value;
+	  std::optional<BOOL> return_value;
 	  DWORD attr_flags = relocate_aslr_flags;
 	  if (!UpdateProcThreadAttribute (info_ex.lpAttributeList, 0,
 					  mitigation_policy,
diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h
index e3ea7db..0dc37b2 100644
--- a/gdb/nat/windows-nat.h
+++ b/gdb/nat/windows-nat.h
@@ -23,7 +23,7 @@
 #include <psapi.h>
 #include <vector>
 
-#include "gdbsupport/gdb_optional.h"
+#include <optional>
 #include "target/waitstatus.h"
 
 #define STATUS_WX86_BREAKPOINT 0x4000001F
@@ -246,7 +246,7 @@ struct windows_process_info
      remove it from the list of pending stops, set 'current_event', and
      return it.  Otherwise, return an empty optional.  */
 
-  gdb::optional<pending_stop> fetch_pending_stop (bool debug_events);
+  std::optional<pending_stop> fetch_pending_stop (bool debug_events);
 
   const char *pid_to_exec_file (int);