SQL2003 mandates that ln() and power() emit particular SQLSTATE error
codes for a few illegal combinations of arguments (in Section 6.27 of my
copy of SQL2003). This patch adds those error codes and changes the
several variants of ln() and power() to emit them as appropriate.

I didn't change log() to emit the same error code as ln() when it is
passed similarly incorrect arguments, on the grounds that the SQLSTATE
code defined by SQL specifically refers to the "natural logarithm". Does
anyone think I should make both log() and ln() return the same SQLSTATE
code, invent a new SQLSTATE for log() errors, and just leave things as
they are? (the latter being my preference...)

I didn't bother adding any regression tests for this behavior, but I can
do so if anyone thinks that's worth doing.

Barring any objections, I intend to apply this patch within 24 hours.

-Neil

Index: doc/src/sgml/errcodes.sgml
===================================================================
RCS file: /var/lib/cvs/pgsql-server/doc/src/sgml/errcodes.sgml,v
retrieving revision 1.5
diff -c -r1.5 errcodes.sgml
*** a/doc/src/sgml/errcodes.sgml	14 May 2004 21:42:27 -0000	1.5
--- b/doc/src/sgml/errcodes.sgml	15 May 2004 06:18:45 -0000
***************
*** 311,316 ****
--- 311,326 ----
  </row>
  
  <row>
+ <entry><literal>2201E</literal></entry>
+ <entry>INVALID ARGUMENT FOR NATURAL LOGARITHM</entry>
+ </row>
+ 
+ <row>
+ <entry><literal>2201F</literal></entry>
+ <entry>INVALID ARGUMENT FOR POWER FUNCTION</entry>
+ </row>
+ 
+ <row>
  <entry><literal>2201G</literal></entry>
  <entry>INVALID ARGUMENT FOR WIDTH BUCKET FUNCTION</entry>
  </row>
Index: src/backend/utils/adt/float.c
===================================================================
RCS file: /var/lib/cvs/pgsql-server/src/backend/utils/adt/float.c,v
retrieving revision 1.104
diff -c -r1.104 float.c
*** a/src/backend/utils/adt/float.c	7 May 2004 00:24:58 -0000	1.104
--- b/src/backend/utils/adt/float.c	15 May 2004 06:32:53 -0000
***************
*** 1450,1455 ****
--- 1450,1465 ----
  	float8		result;
  
  	/*
+ 	 * The SQL spec requires that we emit a particular SQLSTATE error
+ 	 * code for certain error conditions.
+ 	 */
+ 	if ((arg1 == 0 && arg2 < 0) ||
+ 		(arg1 < 0 && trunc(arg2) != arg2))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
+ 				 errmsg("invalid argument for power function")));
+ 
+ 	/*
  	 * We must check both for errno getting set and for a NaN result, in
  	 * order to deal with the vagaries of different platforms...
  	 */
***************
*** 1501,1507 ****
  
  /*
   *		dlog1			- returns the natural logarithm of arg1
-  *						  ("dlog" is already a logging routine...)
   */
  Datum
  dlog1(PG_FUNCTION_ARGS)
--- 1511,1516 ----
***************
*** 1509,1522 ****
  	float8		arg1 = PG_GETARG_FLOAT8(0);
  	float8		result;
  
  	if (arg1 == 0.0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
  				 errmsg("cannot take logarithm of zero")));
- 
  	if (arg1 < 0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
  				 errmsg("cannot take logarithm of a negative number")));
  
  	result = log(arg1);
--- 1518,1534 ----
  	float8		arg1 = PG_GETARG_FLOAT8(0);
  	float8		result;
  
+ 	/*
+ 	 * Emit particular SQLSTATE error codes for ln(). This is required
+ 	 * by the SQL standard.
+ 	 */
  	if (arg1 == 0.0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_NATURAL_LOG),
  				 errmsg("cannot take logarithm of zero")));
  	if (arg1 < 0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_NATURAL_LOG),
  				 errmsg("cannot take logarithm of a negative number")));
  
  	result = log(arg1);
Index: src/backend/utils/adt/numeric.c
===================================================================
RCS file: /var/lib/cvs/pgsql-server/src/backend/utils/adt/numeric.c,v
retrieving revision 1.74
diff -c -r1.74 numeric.c
*** a/src/backend/utils/adt/numeric.c	14 May 2004 21:42:28 -0000	1.74
--- b/src/backend/utils/adt/numeric.c	15 May 2004 06:16:20 -0000
***************
*** 1668,1673 ****
--- 1668,1674 ----
  	Numeric		res;
  	NumericVar	arg1;
  	NumericVar	arg2;
+ 	NumericVar	arg2_trunc;
  	NumericVar	result;
  
  	/*
***************
*** 1681,1690 ****
--- 1682,1707 ----
  	 */
  	init_var(&arg1);
  	init_var(&arg2);
+ 	init_var(&arg2_trunc);
  	init_var(&result);
  
  	set_var_from_num(num1, &arg1);
  	set_var_from_num(num2, &arg2);
+ 	set_var_from_var(&arg2, &arg2_trunc);
+ 
+ 	trunc_var(&arg2_trunc, 0);
+ 
+ 	/*
+ 	 * Return special SQLSTATE error codes for a few conditions
+ 	 * mandated by the standard.
+ 	 */
+ 	if ((cmp_var(&arg1, &const_zero) == 0 &&
+ 		 cmp_var(&arg2, &const_zero) < 0) ||
+ 		(cmp_var(&arg1, &const_zero) < 0 &&
+ 		 cmp_var(&arg2, &arg2_trunc) != 0))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
+ 				 errmsg("invalid argument for power function")));
  
  	/*
  	 * Call power_var() to compute and return the result; note it handles
***************
*** 1696,1701 ****
--- 1713,1719 ----
  
  	free_var(&result);
  	free_var(&arg2);
+ 	free_var(&arg2_trunc);
  	free_var(&arg1);
  
  	PG_RETURN_NUMERIC(res);
***************
*** 4408,4417 ****
  	NumericVar	elem;
  	NumericVar	fact;
  	int			local_rscale;
  
! 	if (cmp_var(arg, &const_zero) <= 0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
  				 errmsg("cannot take logarithm of a negative number")));
  
  	local_rscale = rscale + 8;
--- 4426,4441 ----
  	NumericVar	elem;
  	NumericVar	fact;
  	int			local_rscale;
+ 	int			cmp;
  
! 	cmp = cmp_var(arg, &const_zero);
! 	if (cmp == 0)
  		ereport(ERROR,
! 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_NATURAL_LOG),
! 				 errmsg("cannot take logarithm of zero")));
! 	else if (cmp < 0)
! 		ereport(ERROR,
! 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_NATURAL_LOG),
  				 errmsg("cannot take logarithm of a negative number")));
  
  	local_rscale = rscale + 8;
Index: src/include/utils/errcodes.h
===================================================================
RCS file: /var/lib/cvs/pgsql-server/src/include/utils/errcodes.h,v
retrieving revision 1.10
diff -c -r1.10 errcodes.h
*** a/src/include/utils/errcodes.h	14 May 2004 21:42:30 -0000	1.10
--- b/src/include/utils/errcodes.h	15 May 2004 05:24:26 -0000
***************
*** 116,122 ****
  #define ERRCODE_ESCAPE_CHARACTER_CONFLICT	MAKE_SQLSTATE('2','2', '0','0','B')
  #define ERRCODE_INDICATOR_OVERFLOW			MAKE_SQLSTATE('2','2', '0','2','2')
  #define ERRCODE_INTERVAL_FIELD_OVERFLOW		MAKE_SQLSTATE('2','2', '0','1','5')
! #define ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION		MAKE_SQLSTATE('2','2', '0', '1', 'G')
  #define ERRCODE_INVALID_CHARACTER_VALUE_FOR_CAST		MAKE_SQLSTATE('2','2', '0','1','8')
  #define ERRCODE_INVALID_DATETIME_FORMAT		MAKE_SQLSTATE('2','2', '0','0','7')
  #define ERRCODE_INVALID_ESCAPE_CHARACTER	MAKE_SQLSTATE('2','2', '0','1','9')
--- 116,124 ----
  #define ERRCODE_ESCAPE_CHARACTER_CONFLICT	MAKE_SQLSTATE('2','2', '0','0','B')
  #define ERRCODE_INDICATOR_OVERFLOW			MAKE_SQLSTATE('2','2', '0','2','2')
  #define ERRCODE_INTERVAL_FIELD_OVERFLOW		MAKE_SQLSTATE('2','2', '0','1','5')
! #define ERRCODE_INVALID_ARGUMENT_FOR_NATURAL_LOG	MAKE_SQLSTATE('2','2', '0','1','E')
! #define ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION	MAKE_SQLSTATE('2','2', '0', '1', 'F')
! #define ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION	MAKE_SQLSTATE('2','2', '0', '1', 'G')
  #define ERRCODE_INVALID_CHARACTER_VALUE_FOR_CAST		MAKE_SQLSTATE('2','2', '0','1','8')
  #define ERRCODE_INVALID_DATETIME_FORMAT		MAKE_SQLSTATE('2','2', '0','0','7')
  #define ERRCODE_INVALID_ESCAPE_CHARACTER	MAKE_SQLSTATE('2','2', '0','1','9')
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