Add macros wrapping all usage of gcc's __attribute__.

Until now __attribute__() was defined to be empty for all compilers but
gcc. That's problematic because it prevents using it in other compilers;
which is necessary e.g. for atomics portability.  It's also just
generally dubious to do so in a header as widely included as c.h.

Instead add pg_attribute_format_arg, pg_attribute_printf,
pg_attribute_noreturn macros which are implemented in the compilers that
understand them. Also add pg_attribute_noreturn and pg_attribute_packed,
but don't provide fallbacks, since they can affect functionality.

This means that external code that, possibly unwittingly, relied on
__attribute__ defined to be empty on !gcc compilers may now run into
warnings or errors on those compilers. But there shouldn't be many
occurances of that and it's hard to work around...

Discussion: 54B58BA3.8040302@ohmu.fi
Author: Oskari Saarenmaa, with some minor changes by me.

10 files changed, 12 insertions, 12 deletions

diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index fb4a2ddfcf0..4a51defc529 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -36,7 +36,7 @@ static void
 report_invalid_record(XLogReaderState *state, const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
+pg_attribute_printf(2, 3);
 
 static void ResetDecoder(XLogReaderState *state);
 
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 77158c1e8f0..ee556f3600d 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -286,8 +286,8 @@ int			AutovacuumLauncherPid = 0;
 static pid_t avlauncher_forkexec(void);
 static pid_t avworker_forkexec(void);
 #endif
-NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]) __attribute__((noreturn));
-NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) __attribute__((noreturn));
+NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]) pg_attribute_noreturn;
+NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_noreturn;
 
 static Oid	do_start_worker(void);
 static void launcher_determine_sleep(bool canlaunch, bool recursing,
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 9b689af9156..800ae9362f8 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -86,7 +86,7 @@ static volatile sig_atomic_t ready_to_stop = false;
 static pid_t pgarch_forkexec(void);
 #endif
 
-NON_EXEC_STATIC void PgArchiverMain(int argc, char *argv[]) __attribute__((noreturn));
+NON_EXEC_STATIC void PgArchiverMain(int argc, char *argv[]) pg_attribute_noreturn;
 static void pgarch_exit(SIGNAL_ARGS);
 static void ArchSigHupHandler(SIGNAL_ARGS);
 static void ArchSigTermHandler(SIGNAL_ARGS);
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 1148e29090d..abdfe8947a9 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -251,7 +251,7 @@ static instr_time total_func_time;
 static pid_t pgstat_forkexec(void);
 #endif
 
-NON_EXEC_STATIC void PgstatCollectorMain(int argc, char *argv[]) __attribute__((noreturn));
+NON_EXEC_STATIC void PgstatCollectorMain(int argc, char *argv[]) pg_attribute_noreturn;
 static void pgstat_exit(SIGNAL_ARGS);
 static void pgstat_beshutdown_hook(int code, Datum arg);
 static void pgstat_sighup_handler(SIGNAL_ARGS);
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index ac431e5dd5a..9b2e7f310c9 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -380,8 +380,8 @@ static void LogChildExit(int lev, const char *procname,
 			 int pid, int exitstatus);
 static void PostmasterStateMachine(void);
 static void BackendInitialize(Port *port);
-static void BackendRun(Port *port) __attribute__((noreturn));
-static void ExitPostmaster(int status) __attribute__((noreturn));
+static void BackendRun(Port *port) pg_attribute_noreturn;
+static void ExitPostmaster(int status) pg_attribute_noreturn;
 static int	ServerLoop(void);
 static int	BackendStartup(Port *port);
 static int	ProcessStartupPacket(Port *port, bool SSLdone);
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 14ff1477c16..a27401f3700 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -130,7 +130,7 @@ static volatile sig_atomic_t rotation_requested = false;
 static pid_t syslogger_forkexec(void);
 static void syslogger_parseArgs(int argc, char *argv[]);
 #endif
-NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) __attribute__((noreturn));
+NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn;
 static void process_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
 static void flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
 static void open_csvlogfile(void);
diff --git a/src/backend/replication/repl_scanner.l b/src/backend/replication/repl_scanner.l
index 449c127e188..9abe4758429 100644
--- a/src/backend/replication/repl_scanner.l
+++ b/src/backend/replication/repl_scanner.l
@@ -205,7 +205,7 @@ addlitchar(unsigned char ychar)
 	appendStringInfoChar(&litbuf, ychar);
 }
 
-void __attribute__((noreturn))
+void pg_attribute_noreturn
 yyerror(const char *message)
 {
 	ereport(ERROR,
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index af5c1cc3ba2..295611913aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -193,7 +193,7 @@ typedef void (*WalSndSendDataCallback) (void);
 static void WalSndLoop(WalSndSendDataCallback send_data);
 static void InitWalSenderSlot(void);
 static void WalSndKill(int code, Datum arg);
-static void WalSndShutdown(void) __attribute__((noreturn));
+static void WalSndShutdown(void) pg_attribute_noreturn;
 static void XLogSendPhysical(void);
 static void XLogSendLogical(void);
 static void WalSndDone(WalSndSendDataCallback send_data);
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 4e0cc30f1cc..b952c7c98ed 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -86,7 +86,7 @@ static const char *
 err_gettext(const char *str)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format_arg(1)));
+pg_attribute_format_arg(1);
 static void set_errdata_field(MemoryContextData *cxt, char **ptr, const char *str);
 
 /* Global variables */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 0da1981e386..6eaab4352aa 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -132,7 +132,7 @@ char	   *GUC_check_errhint_string;
 static void
 do_serialize(char **destptr, Size *maxbytes, const char *fmt,...)
 /* This lets gcc check the format string for consistency. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 3, 4)));
+pg_attribute_printf(3, 4);
 
 static void set_config_sourcefile(const char *name, char *sourcefile,
 					  int sourceline);