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.

4 files changed, 7 insertions, 7 deletions

diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 64579d29404..b9b630a222f 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -548,7 +548,7 @@ extern PGresult *pqPrepareAsyncResult(PGconn *conn);
 extern void
 pqInternalNotice(const PGNoticeHooks *hooks, const char *fmt,...)
 /* This lets gcc check the format string for consistency. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
+pg_attribute_printf(2, 3);
 extern void pqSaveMessageField(PGresult *res, char code,
 				   const char *value);
 extern void pqSaveParameterStatus(PGconn *conn, const char *name,
@@ -653,10 +653,10 @@ extern ssize_t pgtls_write(PGconn *conn, const void *ptr, size_t len);
 #ifdef ENABLE_NLS
 extern char *
 libpq_gettext(const char *msgid)
-__attribute__((format_arg(1)));
+pg_attribute_format_arg(1);
 extern char *
 libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n)
-__attribute__((format_arg(1))) __attribute__((format_arg(2)));
+pg_attribute_format_arg(1) pg_attribute_format_arg(2);
 #else
 #define libpq_gettext(x) (x)
 #define libpq_ngettext(s, p, n) ((n) == 1 ? (s) : (p))
diff --git a/src/interfaces/libpq/pqexpbuffer.c b/src/interfaces/libpq/pqexpbuffer.c
index 15117a3d173..43df56a1e09 100644
--- a/src/interfaces/libpq/pqexpbuffer.c
+++ b/src/interfaces/libpq/pqexpbuffer.c
@@ -39,7 +39,7 @@ static const char oom_buffer[1] = "";
 
 static bool
 appendPQExpBufferVA(PQExpBuffer str, const char *fmt, va_list args)
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 0)));
+pg_attribute_printf(2, 0);
 
 
 /*
diff --git a/src/interfaces/libpq/pqexpbuffer.h b/src/interfaces/libpq/pqexpbuffer.h
index 3598271fa9e..345d20376b8 100644
--- a/src/interfaces/libpq/pqexpbuffer.h
+++ b/src/interfaces/libpq/pqexpbuffer.h
@@ -149,7 +149,7 @@ extern int	enlargePQExpBuffer(PQExpBuffer str, size_t needed);
 extern void
 printfPQExpBuffer(PQExpBuffer str, const char *fmt,...)
 /* This extension allows gcc to check the format string */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
+pg_attribute_printf(2, 3);
 
 /*------------------------
  * appendPQExpBuffer
@@ -161,7 +161,7 @@ __attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
 extern void
 appendPQExpBuffer(PQExpBuffer str, const char *fmt,...)
 /* This extension allows gcc to check the format string */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
+pg_attribute_printf(2, 3);
 
 /*------------------------
  * appendPQExpBufferStr
diff --git a/src/interfaces/libpq/win32.c b/src/interfaces/libpq/win32.c
index 4d2497afe9d..04c5ed4b724 100644
--- a/src/interfaces/libpq/win32.c
+++ b/src/interfaces/libpq/win32.c
@@ -36,7 +36,7 @@
 #ifdef ENABLE_NLS
 extern char *
 libpq_gettext(const char *msgid)
-__attribute__((format_arg(1)));
+pg_attribute_format_arg(1);
 #else
 #define libpq_gettext(x) (x)
 #endif