Unify calling conventions for postgres/postmaster sub-main functions

There was a wild mix of calling conventions: Some were declared to
return void and didn't return, some returned an int exit code, some
claimed to return an exit code, which the callers checked, but
actually never returned, and so on.

Now all of these functions are declared to return void and decorated
with attribute noreturn and don't return.  That's easiest, and most
code already worked that way.

src/include/bootstrap/bootstrap.h

@@ -40,7 +40,7 @@ extern Form_pg_attribute attrtypes[MAXATTR];
 extern int	numattr;
 
 
-extern void AuxiliaryProcessMain(int argc, char *argv[]);
+extern void AuxiliaryProcessMain(int argc, char *argv[]) __attribute__((noreturn));
 
 extern void err_out(void);
 

src/include/pgstat.h

@@ -749,7 +749,7 @@ extern void pgstat_reset_all(void);
 extern void allow_immediate_pgstat_restart(void);
 
 #ifdef EXEC_BACKEND
-extern void PgstatCollectorMain(int argc, char *argv[]);
+extern void PgstatCollectorMain(int argc, char *argv[]) __attribute__((noreturn));
 #endif
 
 

src/include/postmaster/autovacuum.h

@@ -52,8 +52,8 @@ extern void AutoVacWorkerFailed(void);
 extern void AutoVacuumUpdateDelay(void);
 
 #ifdef EXEC_BACKEND
-extern void AutoVacLauncherMain(int argc, char *argv[]);
-extern void AutoVacWorkerMain(int argc, char *argv[]);
+extern void AutoVacLauncherMain(int argc, char *argv[]) __attribute__((noreturn));
+extern void AutoVacWorkerMain(int argc, char *argv[]) __attribute__((noreturn));
 extern void AutovacuumWorkerIAm(void);
 extern void AutovacuumLauncherIAm(void);
 #endif

src/include/postmaster/bgwriter.h

@@ -25,8 +25,8 @@ extern int	CheckPointTimeout;
 extern int	CheckPointWarning;
 extern double CheckPointCompletionTarget;
 
-extern void BackgroundWriterMain(void);
-extern void CheckpointerMain(void);
+extern void BackgroundWriterMain(void) __attribute__((noreturn));
+extern void CheckpointerMain(void) __attribute__((noreturn));
 
 extern void RequestCheckpoint(int flags);
 extern void CheckpointWriteDelay(int flags, double progress);

src/include/postmaster/pgarch.h

@@ -20,7 +20,7 @@
 extern int	pgarch_start(void);
 
 #ifdef EXEC_BACKEND
-extern void PgArchiverMain(int argc, char *argv[]);
+extern void PgArchiverMain(int argc, char *argv[]) __attribute__((noreturn));
 #endif
 
 #endif   /* _PGARCH_H */

src/include/postmaster/postmaster.h

@@ -46,14 +46,14 @@ extern int	postmaster_alive_fds[2];
 
 extern const char *progname;
 
-extern int	PostmasterMain(int argc, char *argv[]);
+extern void PostmasterMain(int argc, char *argv[]) __attribute__((noreturn));
 extern void ClosePostmasterPorts(bool am_syslogger);
 
 extern int	MaxLivePostmasterChildren(void);
 
 #ifdef EXEC_BACKEND
 extern pid_t postmaster_forkexec(int argc, char *argv[]);
-extern int	SubPostmasterMain(int argc, char *argv[]);
+extern void	SubPostmasterMain(int argc, char *argv[]) __attribute__((noreturn));
 
 extern Size ShmemBackendArraySize(void);
 extern void ShmemBackendArrayAllocation(void);

src/include/postmaster/startup.h

@@ -13,7 +13,7 @@
 #define _STARTUP_H
 
 extern void HandleStartupProcInterrupts(void);
-extern void StartupProcessMain(void);
+extern void StartupProcessMain(void) __attribute__((noreturn));
 extern void PreRestoreCommand(void);
 extern void PostRestoreCommand(void);
 extern bool IsPromoteTriggered(void);

src/include/postmaster/syslogger.h

@@ -84,7 +84,7 @@ extern int	SysLogger_Start(void);
 extern void write_syslogger_file(const char *buffer, int count, int dest);
 
 #ifdef EXEC_BACKEND
-extern void SysLoggerMain(int argc, char *argv[]);
+extern void SysLoggerMain(int argc, char *argv[]) __attribute__((noreturn));
 #endif
 
 #endif   /* _SYSLOGGER_H */

src/include/postmaster/walwriter.h

@@ -15,6 +15,6 @@
 /* GUC options */
 extern int	WalWriterDelay;
 
-extern void WalWriterMain(void);
+extern void WalWriterMain(void) __attribute__((noreturn));
 
 #endif   /* _WALWRITER_H */

src/include/replication/walreceiver.h

@@ -109,7 +109,7 @@ typedef void (*walrcv_disconnect_type) (void);
 extern PGDLLIMPORT walrcv_disconnect_type walrcv_disconnect;
 
 /* prototypes for functions in walreceiver.c */
-extern void WalReceiverMain(void);
+extern void WalReceiverMain(void) __attribute__((noreturn));
 
 /* prototypes for functions in walreceiverfuncs.c */
 extern Size WalRcvShmemSize(void);

src/include/replication/walsender.h

@@ -26,7 +26,7 @@ extern volatile sig_atomic_t walsender_ready_to_stop;
 extern int	max_wal_senders;
 extern int	replication_timeout;
 
-extern int	WalSenderMain(void);
+extern void WalSenderMain(void) __attribute__((noreturn));
 extern void WalSndSignals(void);
 extern Size WalSndShmemSize(void);
 extern void WalSndShmemInit(void);

src/include/storage/ipc.h

@@ -64,7 +64,7 @@ typedef void (*shmem_startup_hook_type) (void);
 /* ipc.c */
 extern bool proc_exit_inprogress;
 
-extern void proc_exit(int code);
+extern void proc_exit(int code) __attribute__((noreturn));
 extern void shmem_exit(int code);
 extern void on_proc_exit(pg_on_exit_callback function, Datum arg);
 extern void on_shmem_exit(pg_on_exit_callback function, Datum arg);

src/include/tcop/tcopprot.h

@@ -61,7 +61,7 @@ extern bool check_max_stack_depth(int *newval, void **extra, GucSource source);
 extern void assign_max_stack_depth(int newval, void *extra);
 
 extern void die(SIGNAL_ARGS);
-extern void quickdie(SIGNAL_ARGS);
+extern void quickdie(SIGNAL_ARGS) __attribute__((noreturn));
 extern void StatementCancelHandler(SIGNAL_ARGS);
 extern void FloatExceptionHandler(SIGNAL_ARGS);
 extern void RecoveryConflictInterrupt(ProcSignalReason reason); /* called from SIGUSR1
@@ -70,7 +70,7 @@ extern void prepare_for_client_read(void);
 extern void client_read_ended(void);
 extern const char *process_postgres_switches(int argc, char *argv[],
 						  GucContext ctx);
-extern int	PostgresMain(int argc, char *argv[], const char *username);
+extern void PostgresMain(int argc, char *argv[], const char *username) __attribute__((noreturn));
 extern long get_stack_depth_rlimit(void);
 extern void ResetUsage(void);
 extern void ShowUsage(const char *title);

src/include/utils/help_config.h

@@ -12,6 +12,6 @@
 #ifndef HELP_CONFIG_H
 #define HELP_CONFIG_H 1
 
-extern int	GucInfoMain(void);
+extern void GucInfoMain(void) __attribute__((noreturn));
 
 #endif