Remove partial, broken support for NULL pointers when fetching attributes.

Previously, fastgetattr() and heap_getattr() tested their fourth argument
against a null pointer, but any attempt to use them with a literal-NULL
fourth argument evaluated to *(void *)0, resulting in a compiler error.
Remove these NULL tests to avoid leading future readers of this code to
believe that this has a chance of working.  Also clean up related legacy
code in nocachegetattr(), heap_getsysattr(), and nocache_index_getattr().

The new coding standard is that any code which calls a getattr-type
function or macro which takes an isnull argument MUST pass a valid
boolean pointer.  Per discussion with Bruce Momjian, Tom Lane, Alvaro
Herrera.

src/backend/access/common/heaptuple.c

@@ -50,7 +50,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.129 2010/01/02 16:57:33 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.130 2010/01/10 04:26:36 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -323,8 +323,7 @@ heap_attisnull(HeapTuple tup, int attnum)
 Datum
 nocachegetattr(HeapTuple tuple,
 			   int attnum,
-			   TupleDesc tupleDesc,
-			   bool *isnull)
+			   TupleDesc tupleDesc)
 {
 	HeapTupleHeader tup = tuple->t_data;
 	Form_pg_attribute *att = tupleDesc->attrs;
@@ -333,8 +332,6 @@ nocachegetattr(HeapTuple tuple,
 	bool		slow = false;	/* do we have to walk attrs? */
 	int			off;			/* current offset within data */
 
-	(void) isnull;				/* not used */
-
 	/* ----------------
 	 *	 Three cases:
 	 *
@@ -344,50 +341,15 @@ nocachegetattr(HeapTuple tuple,
 	 * ----------------
 	 */
 
-#ifdef IN_MACRO
-/* This is handled in the macro */
-	Assert(attnum > 0);
-
-	if (isnull)
-		*isnull = false;
-#endif
-
 	attnum--;
 
-	if (HeapTupleNoNulls(tuple))
-	{
-#ifdef IN_MACRO
-/* This is handled in the macro */
-		if (att[attnum]->attcacheoff >= 0)
-		{
-			return fetchatt(att[attnum],
-							(char *) tup + tup->t_hoff +
-							att[attnum]->attcacheoff);
-		}
-#endif
-	}
-	else
+	if (!HeapTupleNoNulls(tuple))
 	{
 		/*
 		 * there's a null somewhere in the tuple
 		 *
-		 * check to see if desired att is null
-		 */
-
-#ifdef IN_MACRO
-/* This is handled in the macro */
-		if (att_isnull(attnum, bp))
-		{
-			if (isnull)
-				*isnull = true;
-			return (Datum) NULL;
-		}
-#endif
-
-		/*
-		 * Now check to see if any preceding bits are null...
+		 * check to see if any preceding bits are null...
 		 */
-		{
 		int byte = attnum >> 3;
 		int			finalbit = attnum & 0x07;
 
@@ -409,7 +371,6 @@ nocachegetattr(HeapTuple tuple,
 			}
 		}
 	}
-	}
 
 	tp = (char *) tup + tup->t_hoff;
 
@@ -567,7 +528,6 @@ heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
 	Assert(tup);
 
 	/* Currently, no sys attribute ever reads as NULL. */
-	if (isnull)
 	*isnull = false;
 
 	switch (attnum)

src/backend/access/common/indextuple.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/common/indextuple.c,v 1.90 2010/01/02 16:57:33 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/common/indextuple.c,v 1.91 2010/01/10 04:26:36 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -200,8 +200,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
 Datum
 nocache_index_getattr(IndexTuple tup,
 					  int attnum,
-					  TupleDesc tupleDesc,
-					  bool *isnull)
+					  TupleDesc tupleDesc)
 {
 	Form_pg_attribute *att = tupleDesc->attrs;
 	char	   *tp;				/* ptr to data part of tuple */
@@ -210,8 +209,6 @@ nocache_index_getattr(IndexTuple tup,
 	int			data_off;		/* tuple data offset */
 	int			off;			/* current offset within data */
 
-	(void) isnull;				/* not used */
-
 	/* ----------------
 	 *	 Three cases:
 	 *
@@ -221,31 +218,11 @@ nocache_index_getattr(IndexTuple tup,
 	 * ----------------
 	 */
 
-#ifdef IN_MACRO
-/* This is handled in the macro */
-	Assert(PointerIsValid(isnull));
-	Assert(attnum > 0);
-
-	*isnull = false;
-#endif
-
 	data_off = IndexInfoFindDataOffset(tup->t_info);
 
 	attnum--;
 
-	if (!IndexTupleHasNulls(tup))
-	{
-#ifdef IN_MACRO
-/* This is handled in the macro */
-		if (att[attnum]->attcacheoff >= 0)
-		{
-			return fetchatt(att[attnum],
-							(char *) tup + data_off +
-							att[attnum]->attcacheoff);
-		}
-#endif
-	}
-	else
+	if (IndexTupleHasNulls(tup))
 	{
 		/*
 		 * there's a null somewhere in the tuple
@@ -256,16 +233,6 @@ nocache_index_getattr(IndexTuple tup,
 		/* XXX "knows" t_bits are just after fixed tuple header! */
 		bp = (bits8 *) ((char *) tup + sizeof(IndexTupleData));
 
-#ifdef IN_MACRO
-/* This is handled in the macro */
-
-		if (att_isnull(attnum, bp))
-		{
-			*isnull = true;
-			return (Datum) NULL;
-		}
-#endif
-
 		/*
 		 * Now check to see if any preceding bits are null...
 		 */

src/backend/access/heap/heapam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.280 2010/01/02 16:57:34 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.281 2010/01/10 04:26:36 rhaas Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -834,7 +834,7 @@ fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
 	return (
 			(attnum) > 0 ?
 			(
-			 ((isnull) ? (*(isnull) = false) : (dummyret) NULL),
+			 (*(isnull) = false),
 			 HeapTupleNoNulls(tup) ?
 			 (
 			  (tupleDesc)->attrs[(attnum) - 1]->attcacheoff >= 0 ?
@@ -844,18 +844,18 @@ fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
 						(tupleDesc)->attrs[(attnum) - 1]->attcacheoff)
 			   )
 			  :
-			  nocachegetattr((tup), (attnum), (tupleDesc), (isnull))
+			  nocachegetattr((tup), (attnum), (tupleDesc))
 			  )
 			 :
 			 (
 			  att_isnull((attnum) - 1, (tup)->t_data->t_bits) ?
 			  (
-			   ((isnull) ? (*(isnull) = true) : (dummyret) NULL),
+			   (*(isnull) = true),
 			   (Datum) NULL
 			   )
 			  :
 			  (
-			   nocachegetattr((tup), (attnum), (tupleDesc), (isnull))
+			   nocachegetattr((tup), (attnum), (tupleDesc))
 			   )
 			  )
 			 )

src/include/access/htup.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.109 2010/01/02 16:58:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.110 2010/01/10 04:26:36 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -763,7 +763,7 @@ extern void HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
 #define fastgetattr(tup, attnum, tupleDesc, isnull)					\
 (																	\
 	AssertMacro((attnum) > 0),										\
-	(((isnull) != NULL) ? (*(isnull) = false) : (dummyret)NULL),	\
+	(*(isnull) = false),											\
 	HeapTupleNoNulls(tup) ?											\
 	(																\
 		(tupleDesc)->attrs[(attnum)-1]->attcacheoff >= 0 ?			\
@@ -773,18 +773,18 @@ extern void HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
 					(tupleDesc)->attrs[(attnum)-1]->attcacheoff)	\
 		)															\
 		:															\
-			nocachegetattr((tup), (attnum), (tupleDesc), (isnull))	\
+			nocachegetattr((tup), (attnum), (tupleDesc))			\
 	)																\
 	:																\
 	(																\
 		att_isnull((attnum)-1, (tup)->t_data->t_bits) ?				\
 		(															\
-			(((isnull) != NULL) ? (*(isnull) = true) : (dummyret)NULL),		\
+			(*(isnull) = true),										\
 			(Datum)NULL												\
 		)															\
 		:															\
 		(															\
-			nocachegetattr((tup), (attnum), (tupleDesc), (isnull))	\
+			nocachegetattr((tup), (attnum), (tupleDesc))			\
 		)															\
 	)																\
 )
@@ -818,7 +818,7 @@ extern Datum fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
 		( \
 			((attnum) > (int) HeapTupleHeaderGetNatts((tup)->t_data)) ? \
 			( \
-				(((isnull) != NULL) ? (*(isnull) = true) : (dummyret)NULL), \
+				(*(isnull) = true), \
 				(Datum)NULL \
 			) \
 			: \
@@ -838,7 +838,7 @@ extern void heap_fill_tuple(TupleDesc tupleDesc,
 				uint16 *infomask, bits8 *bit);
 extern bool heap_attisnull(HeapTuple tup, int attnum);
 extern Datum nocachegetattr(HeapTuple tup, int attnum,
-			   TupleDesc att, bool *isnull);
+			   TupleDesc att);
 extern Datum heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
 				bool *isnull);
 extern HeapTuple heap_copytuple(HeapTuple tuple);

src/include/access/itup.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/itup.h,v 1.53 2010/01/02 16:58:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/itup.h,v 1.54 2010/01/10 04:26:36 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,7 +110,7 @@ typedef IndexAttributeBitMapData *IndexAttributeBitMap;
 			+ (tupleDesc)->attrs[(attnum)-1]->attcacheoff) \
 		) \
 		: \
-			nocache_index_getattr((tup), (attnum), (tupleDesc), (isnull)) \
+			nocache_index_getattr((tup), (attnum), (tupleDesc)) \
 	) \
 	: \
 	( \
@@ -121,7 +121,7 @@ typedef IndexAttributeBitMapData *IndexAttributeBitMap;
 		) \
 		: \
 		( \
-			nocache_index_getattr((tup), (attnum), (tupleDesc), (isnull)) \
+			nocache_index_getattr((tup), (attnum), (tupleDesc)) \
 		) \
 	) \
 )
@@ -142,7 +142,7 @@ typedef IndexAttributeBitMapData *IndexAttributeBitMap;
 extern IndexTuple index_form_tuple(TupleDesc tupleDescriptor,
 				 Datum *values, bool *isnull);
 extern Datum nocache_index_getattr(IndexTuple tup, int attnum,
-					  TupleDesc tupleDesc, bool *isnull);
+					  TupleDesc tupleDesc);
 extern void index_deform_tuple(IndexTuple tup, TupleDesc tupleDescriptor,
 				 Datum *values, bool *isnull);
 extern IndexTuple CopyIndexTuple(IndexTuple source);