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, 23 insertions, 23 deletions

diff --git a/src/include/utils/datetime.h b/src/include/utils/datetime.h
index 6b8ab3c6564..3a2335523d0 100644
--- a/src/include/utils/datetime.h
+++ b/src/include/utils/datetime.h
@@ -315,7 +315,7 @@ extern int DecodeISO8601Interval(char *str,
 					  int *dtype, struct pg_tm * tm, fsec_t *fsec);
 
 extern void DateTimeParseError(int dterr, const char *str,
-				   const char *datatype) __attribute__((noreturn));
+				   const char *datatype) pg_attribute_noreturn;
 
 extern int	DetermineTimeZoneOffset(struct pg_tm * tm, pg_tz *tzp);
 extern int	DetermineTimeZoneAbbrevOffset(struct pg_tm * tm, const char *abbr, pg_tz *tzp);
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index b5cfc9cbc88..a82063a57b1 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -147,61 +147,61 @@ extern int
 errmsg(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int
 errmsg_internal(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int
 errmsg_plural(const char *fmt_singular, const char *fmt_plural,
 			  unsigned long n,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 4)))
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 4)));
+pg_attribute_printf(1, 4)
+pg_attribute_printf(2, 4);
 
 extern int
 errdetail(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int
 errdetail_internal(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int
 errdetail_log(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int
 errdetail_log_plural(const char *fmt_singular, const char *fmt_plural,
 					 unsigned long n,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 4)))
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 4)));
+pg_attribute_printf(1, 4)
+pg_attribute_printf(2, 4);
 
 extern int
 errdetail_plural(const char *fmt_singular, const char *fmt_plural,
 				 unsigned long n,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 4)))
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 4)));
+pg_attribute_printf(1, 4)
+pg_attribute_printf(2, 4);
 
 extern int
 errhint(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 /*
  * errcontext() is typically called in error context callback functions, not
@@ -218,7 +218,7 @@ extern int
 errcontext_msg(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 extern int	errhidestmt(bool hide_stmt);
 extern int	errhidecontext(bool hide_ctx);
@@ -278,7 +278,7 @@ extern void
 elog_finish(int elevel, 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);
 
 
 /* Support for constructing error strings separately from ereport() calls */
@@ -288,7 +288,7 @@ extern char *
 format_elog_string(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 
 /* Support for attaching context information to error reports */
@@ -364,7 +364,7 @@ extern PGDLLIMPORT ErrorContextCallback *error_context_stack;
 	} while (0)
 
 /*
- * gcc understands __attribute__((noreturn)); for other compilers, insert
+ * gcc understands pg_attribute_noreturn; for other compilers, insert
  * pg_unreachable() so that the compiler gets the point.
  */
 #ifdef __GNUC__
@@ -423,9 +423,9 @@ extern void EmitErrorReport(void);
 extern ErrorData *CopyErrorData(void);
 extern void FreeErrorData(ErrorData *edata);
 extern void FlushErrorState(void);
-extern void ReThrowError(ErrorData *edata) __attribute__((noreturn));
+extern void ReThrowError(ErrorData *edata) pg_attribute_noreturn;
 extern void ThrowErrorData(ErrorData *edata);
-extern void pg_re_throw(void) __attribute__((noreturn));
+extern void pg_re_throw(void) pg_attribute_noreturn;
 
 extern char *GetErrorContextStack(void);
 
@@ -472,6 +472,6 @@ extern void
 write_stderr(const char *fmt,...)
 /* This extension allows gcc to check the format string for consistency with
    the supplied arguments. */
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 
 #endif   /* ELOG_H */
diff --git a/src/include/utils/help_config.h b/src/include/utils/help_config.h
index 481687f25fd..af529964003 100644
--- a/src/include/utils/help_config.h
+++ b/src/include/utils/help_config.h
@@ -12,6 +12,6 @@
 #ifndef HELP_CONFIG_H
 #define HELP_CONFIG_H 1
 
-extern void GucInfoMain(void) __attribute__((noreturn));
+extern void GucInfoMain(void) pg_attribute_noreturn;
 
 #endif
diff --git a/src/include/utils/palloc.h b/src/include/utils/palloc.h
index 39b318da43a..bd8767520e3 100644
--- a/src/include/utils/palloc.h
+++ b/src/include/utils/palloc.h
@@ -138,9 +138,9 @@ extern char *pnstrdup(const char *in, Size len);
 /* sprintf into a palloc'd buffer --- these are in psprintf.c */
 extern char *
 psprintf(const char *fmt,...)
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+pg_attribute_printf(1, 2);
 extern size_t
 pvsnprintf(char *buf, size_t len, const char *fmt, va_list args)
-__attribute__((format(PG_PRINTF_ATTRIBUTE, 3, 0)));
+pg_attribute_printf(3, 0);
 
 #endif   /* PALLOC_H */