Fix circle_in to accept "(x,y),r" as it's advertised to do.

Our documentation describes four allowed input syntaxes for circles,
but the regression tests tried only three ... with predictable
consequences.  Remarkably, this has been wrong since the circle
datatype was added in 1997, but nobody noticed till now.

David Zhang, with some help from me

Discussion: https://postgr.es/m/332c47fa-d951-7574-b5cc-a8f7f7201202@highgo.ca

src/backend/utils/adt/geo_ops.c

@@ -4604,8 +4604,8 @@ poly_path(PG_FUNCTION_ARGS)
 /*		circle_in		-		convert a string to internal form.
  *
  *		External format: (center and radius of circle)
- *				"((f8,f8)<f8>)"
- *				also supports quick entry style "(f8,f8,f8)"
+ *				"<(f8,f8),f8>"
+ *				also supports quick entry style "f8,f8,f8"
  */
 Datum
 circle_in(PG_FUNCTION_ARGS)
@@ -4619,16 +4619,19 @@ circle_in(PG_FUNCTION_ARGS)
 	s = str;
 	while (isspace((unsigned char) *s))
 		s++;
-	if ((*s == LDELIM_C) || (*s == LDELIM))
+	if (*s == LDELIM_C)
+		depth++, s++;
+	else if (*s == LDELIM)
 	{
-		depth++;
+		/* If there are two left parens, consume the first one */
 		cp = (s + 1);
 		while (isspace((unsigned char) *cp))
 			cp++;
 		if (*cp == LDELIM)
-			s = cp;
+			depth++, s = cp;
 	}
 
+	/* pair_decode will consume parens around the pair, if any */
 	pair_decode(s, &circle->center.x, &circle->center.y, &s, "circle", str);
 
 	if (*s == DELIM)

src/test/regress/expected/circle.out

@@ -6,10 +6,10 @@
 SET extra_float_digits = -1;
 CREATE TABLE CIRCLE_TBL (f1 circle);
 INSERT INTO CIRCLE_TBL VALUES ('<(5,1),3>');
-INSERT INTO CIRCLE_TBL VALUES ('<(1,2),100>');
-INSERT INTO CIRCLE_TBL VALUES ('1,3,5');
-INSERT INTO CIRCLE_TBL VALUES ('((1,2),3)');
-INSERT INTO CIRCLE_TBL VALUES ('<(100,200),10>');
+INSERT INTO CIRCLE_TBL VALUES ('((1,2),100)');
+INSERT INTO CIRCLE_TBL VALUES (' 1 , 3 , 5 ');
+INSERT INTO CIRCLE_TBL VALUES (' ( ( 1 , 2 ) , 3 ) ');
+INSERT INTO CIRCLE_TBL VALUES (' ( 100 , 200 ) , 10 ');
 INSERT INTO CIRCLE_TBL VALUES (' < ( 100 , 1 ) , 115 > ');
 INSERT INTO CIRCLE_TBL VALUES ('<(3,5),0>');	-- Zero radius
 INSERT INTO CIRCLE_TBL VALUES ('<(3,5),NaN>');	-- NaN radius

src/test/regress/sql/circle.sql

@@ -10,13 +10,13 @@ CREATE TABLE CIRCLE_TBL (f1 circle);
 
 INSERT INTO CIRCLE_TBL VALUES ('<(5,1),3>');
 
-INSERT INTO CIRCLE_TBL VALUES ('<(1,2),100>');
+INSERT INTO CIRCLE_TBL VALUES ('((1,2),100)');
 
-INSERT INTO CIRCLE_TBL VALUES ('1,3,5');
+INSERT INTO CIRCLE_TBL VALUES (' 1 , 3 , 5 ');
 
-INSERT INTO CIRCLE_TBL VALUES ('((1,2),3)');
+INSERT INTO CIRCLE_TBL VALUES (' ( ( 1 , 2 ) , 3 ) ');
 
-INSERT INTO CIRCLE_TBL VALUES ('<(100,200),10>');
+INSERT INTO CIRCLE_TBL VALUES (' ( 100 , 200 ) , 10 ');
 
 INSERT INTO CIRCLE_TBL VALUES (' < ( 100 , 1 ) , 115 > ');