[PATCH 1/2] gdb, gdbserver, gdbsupport: use [[maybe_unused]] instead of ATTRIBUTE_UNUSED

[simon.marchi@polymtl.ca]

From: Simon Marchi <simon.marchi@polymtl.ca>

Since we require C++17, replace the uses of the ATTRIBUTE_UNUSED macro
(which expands to __attribute__ ((__unused__))) with the standard
[[maybe_unused]] attribute.

I think that some of these attribute uses are not necessary, but I did
not make an attempt to remove them, that would be for another patch.

Change-Id: I62529d94153c65e2b3c49ff5330292e60c8a0f9e
---
 gdb/inferior.c                       | 4 ++--
 gdb/inflow.c                         | 2 +-
 gdb/linux-fork.c                     | 2 +-
 gdb/mi/mi-interp.c                   | 2 +-
 gdb/python/py-utils.c                | 2 +-
 gdb/remote.c                         | 2 +-
 gdb/source-cache.c                   | 6 +++---
 gdb/thread.c                         | 4 ++--
 gdb/typeprint.c                      | 4 ++--
 gdb/unittests/enum-flags-selftests.c | 4 ++--
 gdb/valprint.c                       | 4 ++--
 gdbserver/linux-aarch64-low.cc       | 6 +++---
 gdbserver/x86-tdesc.h                | 4 ++--
 gdbsupport/safe-strerror.cc          | 4 ++--
 gdbsupport/thread-pool.cc            | 6 +++---
 15 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/gdb/inferior.c b/gdb/inferior.c
index 1481f46cdd18..7d54845f28ac 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -432,7 +432,7 @@ find_inferior_for_program_space (struct program_space *pspace)
 int
 have_inferiors (void)
 {
-  for (inferior *inf ATTRIBUTE_UNUSED : all_non_exited_inferiors ())
+  for ([[maybe_unused]] inferior *inf : all_non_exited_inferiors ())
     return 1;
 
   return 0;
@@ -449,7 +449,7 @@ number_of_live_inferiors (process_stratum_target *proc_target)
 
   for (inferior *inf : all_non_exited_inferiors (proc_target))
     if (inf->has_execution ())
-      for (thread_info &tp ATTRIBUTE_UNUSED : inf->non_exited_threads ())
+      for ([[maybe_unused]] thread_info &tp : inf->non_exited_threads ())
 	{
 	  /* Found a live thread in this inferior, go to the next
 	     inferior.  */
diff --git a/gdb/inflow.c b/gdb/inflow.c
index c40ad2cf5294..e3a080dbd657 100644
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -493,7 +493,7 @@ child_terminal_ours_1 (target_terminal_state desired_state)
 
   if (gdb_tty_state != desired_state)
     {
-      int result ATTRIBUTE_UNUSED;
+      [[maybe_unused]] int result;
 
       /* Ignore SIGTTOU since it will happen when we try to set the
 	 terminal's pgrp.  */
diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 92afa4dde6db..fac35e13afb8 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -963,7 +963,7 @@ inf_has_multiple_threads ()
 
   /* Return true as soon as we see the second thread of the current
      inferior.  */
-  for (thread_info &tp ATTRIBUTE_UNUSED : current_inferior ()->threads ())
+  for ([[maybe_unused]] thread_info &tp : current_inferior ()->threads ())
     if (++count > 1)
       return true;
 
diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index 1a0d34106ed1..998409563e97 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -637,7 +637,7 @@ static bool
 multiple_inferiors_p ()
 {
   int count = 0;
-  for (inferior *inf ATTRIBUTE_UNUSED : all_non_exited_inferiors ())
+  for ([[maybe_unused]] inferior *inf : all_non_exited_inferiors ())
     {
       count++;
       if (count > 1)
diff --git a/gdb/python/py-utils.c b/gdb/python/py-utils.c
index a831b96eb387..3979343acde9 100644
--- a/gdb/python/py-utils.c
+++ b/gdb/python/py-utils.c
@@ -314,7 +314,7 @@ gdb_py_int_as_long (PyObject *obj, long *result)
 
 PyObject *
 gdb_py_generic_dict_getter (PyObject *self,
-			    void *closure ATTRIBUTE_UNUSED)
+			    [[maybe_unused]] void *closure)
 {
   PyObject **py_dict_ptr = gdbpy_dict_wrapper::compute_addr (self);
   PyObject *py_dict = *py_dict_ptr;
diff --git a/gdb/remote.c b/gdb/remote.c
index f8c7383cb037..43df087b83b3 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -4546,7 +4546,7 @@ static bool
 has_single_non_exited_thread (inferior *inf)
 {
   int count = 0;
-  for (thread_info &tp ATTRIBUTE_UNUSED : inf->non_exited_threads ())
+  for ([[maybe_unused]] thread_info &tp : inf->non_exited_threads ())
     if (++count > 1)
       break;
   return count == 1;
diff --git a/gdb/source-cache.c b/gdb/source-cache.c
index 6e8acab35044..0a64745ee585 100644
--- a/gdb/source-cache.c
+++ b/gdb/source-cache.c
@@ -199,9 +199,9 @@ get_language_name (enum language lang)
    succeeded.  */
 
 static bool
-try_source_highlight (std::string &contents ATTRIBUTE_UNUSED,
-		      enum language lang ATTRIBUTE_UNUSED,
-		      const std::string &fullname ATTRIBUTE_UNUSED)
+try_source_highlight ([[maybe_unused]] std::string &contents,
+		      [[maybe_unused]] enum language lang,
+		      [[maybe_unused]] const std::string &fullname)
 {
 #ifdef HAVE_SOURCE_HIGHLIGHT
   if (!use_gnu_source_highlight)
diff --git a/gdb/thread.c b/gdb/thread.c
index 96c733e0629b..ffb980546b93 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -476,7 +476,7 @@ thread_step_over_chain_length (const thread_step_over_list &l)
 {
   int num = 0;
 
-  for (const thread_info &thread ATTRIBUTE_UNUSED : l)
+  for ([[maybe_unused]] const thread_info &thread : l)
     ++num;
 
   return num;
@@ -626,7 +626,7 @@ find_thread (find_thread_callback_ftype callback)
 bool
 any_thread_p ()
 {
-  for (thread_info &tp ATTRIBUTE_UNUSED : all_threads ())
+  for ([[maybe_unused]] thread_info &tp : all_threads ())
     return true;
   return false;
 }
diff --git a/gdb/typeprint.c b/gdb/typeprint.c
index 31a9c1814a31..01c6c218a5d5 100644
--- a/gdb/typeprint.c
+++ b/gdb/typeprint.c
@@ -516,11 +516,11 @@ ptype_command (const char *type_name, int from_tty)
 }
 
 /* Meant to be used in debug sessions, so don't export it in a header file.  */
-extern void ATTRIBUTE_UNUSED debug_type (struct type *type);
+[[maybe_unused]] extern void debug_type (struct type *type);
 
 /* Print TYPE.  */
 
-void ATTRIBUTE_UNUSED
+[[maybe_unused]] void
 debug_type (struct type *type)
 {
   type_print (type, "", gdb_stdlog, 1);
diff --git a/gdb/unittests/enum-flags-selftests.c b/gdb/unittests/enum-flags-selftests.c
index bf748e873035..ca404bfa3ebe 100644
--- a/gdb/unittests/enum-flags-selftests.c
+++ b/gdb/unittests/enum-flags-selftests.c
@@ -70,8 +70,8 @@ static_assert (std::is_trivially_copyable<EnumFlag>::value);
    below.  Their names (and types) match the uppercase type names
    exposed by CHECK_VALID just to make the expressions easier to
    follow.  */
-static RawEnum re ATTRIBUTE_UNUSED;
-static EnumFlag ef ATTRIBUTE_UNUSED;
+[[maybe_unused]] static RawEnum re;
+[[maybe_unused]] static EnumFlag ef;
 
 /* First, compile-time tests that:
 
diff --git a/gdb/valprint.c b/gdb/valprint.c
index 50a4663ca3b5..67bfbf589301 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -1232,11 +1232,11 @@ value_print (struct value *val, struct ui_file *stream,
 }
 
 /* Meant to be used in debug sessions, so don't export it in a header file.  */
-extern void ATTRIBUTE_UNUSED debug_val (struct value *val);
+[[maybe_unused]] extern void debug_val (struct value *val);
 
 /* Print VAL.  */
 
-void ATTRIBUTE_UNUSED
+[[maybe_unused]] void
 debug_val (struct value *val)
 {
   value_print (val, gdb_stdlog, &user_print_options);
diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index a2588a6e2a9c..b68d39e1b803 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -741,7 +741,7 @@ aarch64_target::low_new_fork (process_info *parent,
 
 static void
 aarch64_sve_regs_copy_to_regcache (struct regcache *regcache,
-				   ATTRIBUTE_UNUSED const void *buf)
+				   [[maybe_unused]] const void *buf)
 {
   /* BUF is unused here since we collect the data straight from a ptrace
      request in aarch64_sve_regs_copy_to_reg_buf, therefore bypassing
@@ -776,7 +776,7 @@ aarch64_sve_regs_copy_from_regcache (struct regcache *regcache, void *buf)
 
 static void
 aarch64_za_regs_copy_to_regcache (struct regcache *regcache,
-				  ATTRIBUTE_UNUSED const void *buf)
+				  [[maybe_unused]] const void *buf)
 {
   /* BUF is unused here since we collect the data straight from a ptrace
      request, therefore bypassing gdbserver's own call to ptrace.  */
@@ -822,7 +822,7 @@ aarch64_za_regs_copy_from_regcache (struct regcache *regcache, void *buf)
 
 static void
 aarch64_zt_regs_copy_to_regcache (struct regcache *regcache,
-				  ATTRIBUTE_UNUSED const void *buf)
+				  [[maybe_unused]] const void *buf)
 {
   /* BUF is unused here since we collect the data straight from a ptrace
      request, therefore bypassing gdbserver's own call to ptrace.  */
diff --git a/gdbserver/x86-tdesc.h b/gdbserver/x86-tdesc.h
index 4ed6d6635bbb..ce0c6c1be90d 100644
--- a/gdbserver/x86-tdesc.h
+++ b/gdbserver/x86-tdesc.h
@@ -20,8 +20,8 @@
 
 /* The "expedite" registers for x86 targets.  Since whether the
    variable is used depends on host/configuration, we mark it
-   ATTRIBUTE_UNUSED to keep it simple here.  */
-static const char *i386_expedite_regs[] ATTRIBUTE_UNUSED
+   [[maybe_unused]] to keep it simple here.  */
+[[maybe_unused]] static const char *i386_expedite_regs[]
     = {"ebp", "esp", "eip", NULL};
 
 #ifdef __x86_64__
diff --git a/gdbsupport/safe-strerror.cc b/gdbsupport/safe-strerror.cc
index d53cf84511fd..ad25cfc3d765 100644
--- a/gdbsupport/safe-strerror.cc
+++ b/gdbsupport/safe-strerror.cc
@@ -26,14 +26,14 @@
    function.  */
 
 /* Called if we have a XSI-compliant strerror_r.  */
-ATTRIBUTE_UNUSED static char *
+[[maybe_unused]] static char *
 select_strerror_r (int res, char *buf)
 {
   return res == 0 ? buf : nullptr;
 }
 
 /* Called if we have a GNU strerror_r.  */
-ATTRIBUTE_UNUSED static char *
+[[maybe_unused]] static char *
 select_strerror_r (char *res, char *)
 {
   return res;
diff --git a/gdbsupport/thread-pool.cc b/gdbsupport/thread-pool.cc
index 4dc72e566428..12329ea98831 100644
--- a/gdbsupport/thread-pool.cc
+++ b/gdbsupport/thread-pool.cc
@@ -44,14 +44,14 @@
    takes a printf-style format and an argument.  This wrapper handles the
    difference.  */
 
-ATTRIBUTE_UNUSED static void
+[[maybe_unused]] static void
 do_set_thread_name (int (*set_name) (pthread_t, const char *, void *),
 		    const char *name)
 {
   set_name (pthread_self (), "%s", const_cast<char *> (name));
 }
 
-ATTRIBUTE_UNUSED static void
+[[maybe_unused]] static void
 do_set_thread_name (int (*set_name) (pthread_t, const char *),
 		    const char *name)
 {
@@ -60,7 +60,7 @@ do_set_thread_name (int (*set_name) (pthread_t, const char *),
 
 /* The macOS man page says that pthread_setname_np returns "void", but
    the headers actually declare it returning "int".  */
-ATTRIBUTE_UNUSED static void
+[[maybe_unused]] static void
 do_set_thread_name (int (*set_name) (const char *), const char *name)
 {
   set_name (name);

base-commit: cdfda31c0d6b85cfff7fddeabffa570176161548
-- 
2.54.0