Rely on inline functions even if that causes warnings in older compilers.

So far we have worked around the fact that some very old compilers do
not support 'inline' functions by only using inline functions
conditionally (or not at all). Since such compilers are very rare by
now, we have decided to rely on inline functions from 9.6 onwards.

To avoid breaking these old compilers inline is defined away when not
supported. That'll cause "function x defined but not used" type of
warnings, but since nobody develops on such compilers anymore that's
ok.

This change in policy will allow us to more easily employ inline
functions.

I chose to remove code previously conditional on PG_USE_INLINE as it
seemed confusing to have code dependent on a define that's always
defined.

Blacklisting of compilers, like in c53f738, now has to be done
differently. A platform template can define PG_FORCE_DISABLE_INLINE to
force inline to be defined empty.

Discussion: 20150701161447.GB30708@awork2.anarazel.de

Author: anarazel

config/c-compiler.m4

@@ -17,40 +17,6 @@ fi])# PGAC_C_SIGNED
 
 
 
-# PGAC_C_INLINE
-# -------------
-# Check if the C compiler understands inline functions without being
-# noisy about unused static inline functions. Some older compilers
-# understand inline functions (as tested by AC_C_INLINE) but warn about
-# them if they aren't used in a translation unit.
-#
-# This test used to just define an inline function, but some compilers
-# (notably clang) got too smart and now warn about unused static
-# inline functions when defined inside a .c file, but not when defined
-# in an included header. Since the latter is what we want to use, test
-# to see if the warning appears when the function is in a header file.
-# Not pretty, but it works.
-#
-# Defines: inline, PG_USE_INLINE
-AC_DEFUN([PGAC_C_INLINE],
-[AC_C_INLINE
-AC_CACHE_CHECK([for quiet inline (no complaint if unreferenced)], pgac_cv_c_inline_quietly,
-  [pgac_cv_c_inline_quietly=no
-  if test "$ac_cv_c_inline" != no; then
-    pgac_c_inline_save_werror=$ac_c_werror_flag
-    ac_c_werror_flag=yes
-    AC_LINK_IFELSE([AC_LANG_PROGRAM([#include "$srcdir/config/test_quiet_include.h"],[])],
-                   [pgac_cv_c_inline_quietly=yes])
-    ac_c_werror_flag=$pgac_c_inline_save_werror
-  fi])
-if test "$pgac_cv_c_inline_quietly" != no; then
-  AC_DEFINE_UNQUOTED([PG_USE_INLINE], 1,
-    [Define to 1 if "static inline" works without unwanted warnings from ]
-    [compilations where static inline functions are defined but not called.])
-fi
-])# PGAC_C_INLINE
-
-
 # PGAC_C_PRINTF_ARCHETYPE
 # -----------------------
 # Set the format archetype used by gcc to check printf type functions.  We

config/test_quiet_include.h

@@ -11006,44 +11006,6 @@ _ACEOF
     ;;
 esac
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for quiet inline (no complaint if unreferenced)" >&5
-$as_echo_n "checking for quiet inline (no complaint if unreferenced)... " >&6; }
-if ${pgac_cv_c_inline_quietly+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  pgac_cv_c_inline_quietly=no
-  if test "$ac_cv_c_inline" != no; then
-    pgac_c_inline_save_werror=$ac_c_werror_flag
-    ac_c_werror_flag=yes
-    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include "$srcdir/config/test_quiet_include.h"
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  pgac_cv_c_inline_quietly=yes
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-    ac_c_werror_flag=$pgac_c_inline_save_werror
-  fi
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_c_inline_quietly" >&5
-$as_echo "$pgac_cv_c_inline_quietly" >&6; }
-if test "$pgac_cv_c_inline_quietly" != no; then
-
-cat >>confdefs.h <<_ACEOF
-#define PG_USE_INLINE 1
-_ACEOF
-
-fi
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for printf format archetype" >&5
 $as_echo_n "checking for printf format archetype... " >&6; }
 if ${pgac_cv_printf_archetype+:} false; then :

configure

@@ -1309,7 +1309,7 @@ fi
 
 m4_defun([AC_PROG_CC_STDC], []) dnl We don't want that.
 AC_C_BIGENDIAN
-PGAC_C_INLINE
+AC_C_INLINE
 PGAC_PRINTF_ARCHETYPE
 AC_C_FLEXIBLE_ARRAY_MEMBER
 PGAC_C_SIGNED

configure.in

@@ -18,9 +18,6 @@
  */
 #include "postgres.h"
 
-/* See ilist.h */
-#define ILIST_INCLUDE_DEFINITIONS
-
 #include "lib/ilist.h"
 
 /*

src/backend/lib/ilist.c

@@ -15,9 +15,6 @@
  */
 #include "postgres.h"
 
-/* see pg_list.h */
-#define PG_LIST_INCLUDE_DEFINITIONS
-
 #include "nodes/pg_list.h"
 
 

src/backend/nodes/list.c

@@ -13,13 +13,6 @@
  */
 #include "postgres.h"
 
-/*
- * We want the functions below to be inline; but if the compiler doesn't
- * support that, fall back on providing them as regular functions.  See
- * STATIC_IF_INLINE in c.h.
- */
-#define ATOMICS_INCLUDE_DEFINITIONS
-
 #include "miscadmin.h"
 #include "port/atomics.h"
 #include "storage/spin.h"

src/backend/port/atomics.c

@@ -20,9 +20,6 @@
 #endif
 #include <math.h>
 
-/* See arrayaccess.h */
-#define ARRAYACCESS_INCLUDE_DEFINITIONS
-
 #include "access/htup_details.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"

src/backend/utils/adt/arrayfuncs.c

@@ -19,9 +19,6 @@
  *-------------------------------------------------------------------------
  */
 
-/* see palloc.h.  Must be before postgres.h */
-#define MCXT_INCLUDE_DEFINITIONS
-
 #include "postgres.h"
 
 #include "miscadmin.h"

src/backend/utils/mmgr/mcxt.c

@@ -15,9 +15,6 @@
 
 #include "postgres.h"
 
-/* See sortsupport.h */
-#define SORTSUPPORT_INCLUDE_DEFINITIONS
-
 #include "access/nbtree.h"
 #include "fmgr.h"
 #include "utils/lsyscache.h"

src/backend/utils/sort/sortsupport.c

@@ -952,11 +952,8 @@ extern ItemPointer ginMergeItemPointers(ItemPointerData *a, uint32 na,
 
 /*
  * Merging the results of several gin scans compares item pointers a lot,
- * so we want this to be inlined. But if the compiler doesn't support that,
- * fall back on the non-inline version from itemptr.c. See STATIC_IF_INLINE in
- * c.h.
+ * so we want this to be inlined.
  */
-#ifdef PG_USE_INLINE
 static inline int
 ginCompareItemPointers(ItemPointer a, ItemPointer b)
 {
@@ -970,8 +967,5 @@ ginCompareItemPointers(ItemPointer a, ItemPointer b)
 	else
 		return -1;
 }
-#else
-#define ginCompareItemPointers(a, b) ItemPointerCompare(a, b)
-#endif   /* PG_USE_INLINE */
 
 #endif   /* GIN_PRIVATE_H */

src/include/access/gin_private.h

@@ -53,6 +53,20 @@
 #include "pg_config.h"
 #include "pg_config_manual.h"	/* must be after pg_config.h */
 
+/*
+ * Force disable inlining if PG_FORCE_DISABLE_INLINE is defined. This is used
+ * to work around compiler bugs and might also be useful for investigatory
+ * purposes.
+ *
+ * This is done early (in slightly the wrong section) for two reasons: a) we
+ * don't want to include headers with different settings of this b)
+ * functionality later in this file might want to rely on inline functions.
+ */
+#ifdef PG_FORCE_DISABLE_INLINE
+#undef inline
+#define inline
+#endif
+
 /*
  * We always rely on the WIN32 macro being set by our build system,
  * but _WIN32 is the compiler pre-defined macro. So make sure we define
@@ -920,34 +934,6 @@ typedef NameData *Name;
 #endif
 
 
-/*
- * Function inlining support -- Allow modules to define functions that may be
- * inlined, if the compiler supports it.
- *
- * The function bodies must be defined in the module header prefixed by
- * STATIC_IF_INLINE, protected by a cpp symbol that the module's .c file must
- * define.  If the compiler doesn't support inline functions, the function
- * definitions are pulled in by the .c file as regular (not inline) symbols.
- *
- * The header must also declare the functions' prototypes, protected by
- * !PG_USE_INLINE.
- */
-
-/* declarations which are only visible when not inlining and in the .c file */
-#ifdef PG_USE_INLINE
-#define STATIC_IF_INLINE static inline
-#else
-#define STATIC_IF_INLINE
-#endif   /* PG_USE_INLINE */
-
-/* declarations which are marked inline when inlining, extern otherwise */
-#ifdef PG_USE_INLINE
-#define STATIC_IF_INLINE_DECLARE static inline
-#else
-#define STATIC_IF_INLINE_DECLARE extern
-#endif   /* PG_USE_INLINE */
-
-
 /* ----------------------------------------------------------------
  *				Section 8:	random stuff
  * ----------------------------------------------------------------