Convert *GetDatum() and DatumGet*() macros to inline functions

The previous macro implementations just cast the argument to a target
type but did not check whether the input type was appropriate.  The
function implementation can do better type checking of the input type.

For the *GetDatumFast() macros, converting to an inline function
doesn't work in the !USE_FLOAT8_BYVAL case, but we can use
AssertVariableIsOfTypeMacro() to get a similar level of type checking.

Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/8528fb7e-0aa2-6b54-85fb-0c0886dbd6ed%40enterprisedb.com

Author: petere

contrib/intarray/_int_gist.c

@@ -51,7 +51,7 @@ g_int_consistent(PG_FUNCTION_ARGS)
 
 	/* Oid		subtype = PG_GETARG_OID(3); */
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
-	bool		retval;
+	bool		retval = false; /* silence compiler warning */
 
 	/* this is exact except for RTSameStrategyNumber */
 	*recheck = (strategy == RTSameStrategyNumber);

doc/src/sgml/xfunc.sgml

@@ -2763,7 +2763,7 @@ c_overpaid(PG_FUNCTION_ARGS)
      is  null.   <function>GetAttributeByName</function> returns a <type>Datum</type>
      value that you can convert to the proper data type by using the
      appropriate <function>DatumGet<replaceable>XXX</replaceable>()</function>
-     macro.  Note that the return value is meaningless if the null flag is
+     function.  Note that the return value is meaningless if the null flag is
      set; always check the null flag before trying to do anything with the
      result.
     </para>

src/backend/access/gist/gistutil.c

@@ -280,7 +280,7 @@ gistMakeUnionKey(GISTSTATE *giststate, int attno,
 bool
 gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b)
 {
-	bool		result;
+	bool		result = false; /* silence compiler warning */
 
 	FunctionCall3Coll(&giststate->equalFn[attno],
 					  giststate->supportCollation[attno],

src/backend/tsearch/ts_parse.c

@@ -354,7 +354,7 @@ void
 parsetext(Oid cfgId, ParsedText *prs, char *buf, int buflen)
 {
 	int			type,
-				lenlemm;
+				lenlemm = 0;	/* silence compiler warning */
 	char	   *lemm = NULL;
 	LexizeData	ldata;
 	TSLexeme   *norms;
@@ -529,7 +529,7 @@ void
 hlparsetext(Oid cfgId, HeadlineParsedText *prs, TSQuery query, char *buf, int buflen)
 {
 	int			type,
-				lenlemm;
+				lenlemm = 0;	/* silence compiler warning */
 	char	   *lemm = NULL;
 	LexizeData	ldata;
 	TSLexeme   *norms;

src/backend/utils/mb/mbutils.c

@@ -409,8 +409,8 @@ pg_do_encoding_conversion(unsigned char *src, int len,
 	(void) OidFunctionCall6(proc,
 							Int32GetDatum(src_encoding),
 							Int32GetDatum(dest_encoding),
-							CStringGetDatum(src),
-							CStringGetDatum(result),
+							CStringGetDatum((char *) src),
+							CStringGetDatum((char *) result),
 							Int32GetDatum(len),
 							BoolGetDatum(false));
 
@@ -485,8 +485,8 @@ pg_do_encoding_conversion_buf(Oid proc,
 	result = OidFunctionCall6(proc,
 							  Int32GetDatum(src_encoding),
 							  Int32GetDatum(dest_encoding),
-							  CStringGetDatum(src),
-							  CStringGetDatum(dest),
+							  CStringGetDatum((char *) src),
+							  CStringGetDatum((char *) dest),
 							  Int32GetDatum(srclen),
 							  BoolGetDatum(noError));
 	return DatumGetInt32(result);
@@ -910,8 +910,8 @@ pg_unicode_to_server(pg_wchar c, unsigned char *s)
 	FunctionCall6(Utf8ToServerConvProc,
 				  Int32GetDatum(PG_UTF8),
 				  Int32GetDatum(server_encoding),
-				  CStringGetDatum(c_as_utf8),
-				  CStringGetDatum(s),
+				  CStringGetDatum((char *) c_as_utf8),
+				  CStringGetDatum((char *) s),
 				  Int32GetDatum(c_as_utf8_len),
 				  BoolGetDatum(false));
 }

src/include/access/gin.h

@@ -62,8 +62,18 @@ typedef char GinTernaryValue;
 #define GIN_MAYBE		2		/* don't know if item is present / don't know
 								 * if matches */
 
-#define DatumGetGinTernaryValue(X) ((GinTernaryValue)(X))
-#define GinTernaryValueGetDatum(X) ((Datum)(X))
+static inline GinTernaryValue
+DatumGetGinTernaryValue(Datum X)
+{
+	return (GinTernaryValue) X;
+}
+
+static inline Datum
+GinTernaryValueGetDatum(GinTernaryValue X)
+{
+	return (Datum) X;
+}
+
 #define PG_RETURN_GIN_TERNARY_VALUE(x) return GinTernaryValueGetDatum(x)
 
 /* GUC parameters */

src/include/funcapi.h

@@ -204,7 +204,7 @@ extern TupleDesc build_function_result_tupdesc_t(HeapTuple procTuple);
  * Datum HeapTupleHeaderGetDatum(HeapTupleHeader tuple) - convert a
  *		HeapTupleHeader to a Datum.
  *
- * Macro declarations:
+ * Inline declarations:
  * HeapTupleGetDatum(HeapTuple tuple) - convert a HeapTuple to a Datum.
  *
  * Obsolete routines and macros:
@@ -217,10 +217,6 @@ extern TupleDesc build_function_result_tupdesc_t(HeapTuple procTuple);
  *----------
  */
 
-#define HeapTupleGetDatum(tuple)		HeapTupleHeaderGetDatum((tuple)->t_data)
-/* obsolete version of above */
-#define TupleGetDatum(_slot, _tuple)	HeapTupleGetDatum(_tuple)
-
 extern TupleDesc RelationNameGetTupleDesc(const char *relname);
 extern TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases);
 
@@ -230,6 +226,14 @@ extern AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc);
 extern HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values);
 extern Datum HeapTupleHeaderGetDatum(HeapTupleHeader tuple);
 
+static inline Datum
+HeapTupleGetDatum(const HeapTupleData *tuple)
+{
+	return HeapTupleHeaderGetDatum(tuple->t_data);
+}
+/* obsolete version of above */
+#define TupleGetDatum(_slot, _tuple)	HeapTupleGetDatum(_tuple)
+
 
 /*----------
  *		Support for Set Returning Functions (SRFs)