Code review for domain-constraints patch. Use a new ConstraintTest node

type for runtime constraint checks, instead of misusing the parse-time
Constraint node for the purpose.  Fix some damage introduced into type
coercion logic; in particular ensure that a coerced expression tree will
read out the correct result type when inspected (patch had broken some
RelabelType cases).  Enforce domain NOT NULL constraints against columns
that are omitted from an INSERT.

1 files changed, 79 insertions, 52 deletions

diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index 1016c782d29..397bd4b8b07 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.80 2002/08/22 00:01:42 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.81 2002/08/31 22:10:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -35,7 +35,7 @@ static Node *build_func_call(Oid funcid, Oid rettype, List *args);
 static Oid	find_coercion_function(Oid targetTypeId, Oid sourceTypeId,
 								   bool isExplicit);
 static Oid	find_typmod_coercion_function(Oid typeId);
-static Node	*TypeConstraints(Node *arg, Oid typeId);
+
 
 /* coerce_type()
  * Convert a function argument to a different type.
@@ -49,7 +49,7 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 	if (targetTypeId == inputTypeId ||
 		node == NULL)
 	{
-		/* no conversion needed, but constraints may need to be applied */
+		/* no conversion needed */
 		result = node;
 	}
 	else if (inputTypeId == UNKNOWNOID && IsA(node, Const))
@@ -69,11 +69,12 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 		 * postpone evaluation of the function call until runtime. But
 		 * there is no way to represent a typinput function call as an
 		 * expression tree, because C-string values are not Datums.
+		 * (XXX This *is* possible as of 7.3, do we want to do it?)
 		 */
 		Const	   *con = (Const *) node;
 		Const	   *newcon = makeNode(Const);
 		Type		targetType = typeidType(targetTypeId);
-		Oid			baseTypeId = getBaseType(targetTypeId);
+		char		targetTyptype = typeTypType(targetType);
 
 		newcon->consttype = targetTypeId;
 		newcon->constlen = typeLen(targetType);
@@ -85,16 +86,31 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 		{
 			char	   *val = DatumGetCString(DirectFunctionCall1(unknownout,
 													   con->constvalue));
+
+			/*
+			 * If target is a domain, use the typmod it applies to the base
+			 * type.  Note that we call stringTypeDatum using the domain's
+			 * pg_type row, though.  This works because the domain row has
+			 * the same typinput and typelem as the base type --- ugly...
+			 */
+			if (targetTyptype == 'd')
+				atttypmod = getBaseTypeMod(targetTypeId, atttypmod);
+
 			newcon->constvalue = stringTypeDatum(targetType, val, atttypmod);
 			pfree(val);
 		}
 
-		ReleaseSysCache(targetType);
-
-		/* Test for domain, and apply appropriate constraints */
 		result = (Node *) newcon;
-		if (targetTypeId != baseTypeId)
-			result = (Node *) TypeConstraints(result, targetTypeId);
+
+		/*
+		 * If target is a domain, apply constraints (except for typmod,
+		 * which we assume the input routine took care of).
+		 */
+		if (targetTyptype == 'd')
+			result = coerce_type_constraints(pstate, result, targetTypeId,
+											 false);
+
+		ReleaseSysCache(targetType);
 	}
 	else if (targetTypeId == ANYOID ||
 			 targetTypeId == ANYARRAYOID)
@@ -109,21 +125,18 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 		 * attach a RelabelType node so that the expression will be seen
 		 * to have the intended type when inspected by higher-level code.
 		 *
+		 * Also, domains may have value restrictions beyond the base type
+		 * that must be accounted for.
+		 */
+		result = coerce_type_constraints(pstate, node, targetTypeId, true);
+		/*
 		 * XXX could we label result with exprTypmod(node) instead of
 		 * default -1 typmod, to save a possible length-coercion later?
 		 * Would work if both types have same interpretation of typmod,
-		 * which is likely but not certain.
-		 *
-		 * Domains may have value restrictions beyond the base type that
-		 * must be accounted for.
+		 * which is likely but not certain (wrong if target is a domain,
+		 * in any case).
 		 */
-		Oid			baseTypeId = getBaseType(targetTypeId);
-		result = node;
-		if (targetTypeId != baseTypeId)
-			result = (Node *) TypeConstraints(result, targetTypeId);
-
 		result = (Node *) makeRelabelType(result, targetTypeId, -1);
-
 	}
 	else if (typeInheritsFrom(inputTypeId, targetTypeId))
 	{
@@ -144,8 +157,8 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 		 *
 		 * For domains, we use the coercion function for the base type.
 		 */
-		Oid			funcId;
 		Oid			baseTypeId = getBaseType(targetTypeId);
+		Oid			funcId;
 
 		funcId = find_coercion_function(baseTypeId,
 										getBaseType(inputTypeId),
@@ -157,11 +170,15 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 		result = build_func_call(funcId, baseTypeId, makeList1(node));
 
 		/*
-		 * If domain, relabel with domain type ID and test against domain
-		 * constraints
+		 * If domain, test against domain constraints and relabel with
+		 * domain type ID
 		 */
 		if (targetTypeId != baseTypeId)
-			result = (Node *) TypeConstraints(result, targetTypeId);
+		{
+			result = coerce_type_constraints(pstate, result, targetTypeId,
+											 true);
+			result = (Node *) makeRelabelType(result, targetTypeId, -1);
+		}
 
 		/*
 		 * If the input is a constant, apply the type conversion function
@@ -306,28 +323,21 @@ can_coerce_type(int nargs, Oid *input_typeids, Oid *func_typeids,
  * function should be invoked to do that.
  *
  * "bpchar" (ie, char(N)) and "numeric" are examples of such types.
+ *
+ * This mechanism may seem pretty grotty and in need of replacement by
+ * something in pg_cast, but since typmod is only interesting for datatypes
+ * that have special handling in the grammar, there's not really much
+ * percentage in making it any easier to apply such coercions ...
+ *
+ * NOTE: this does not need to work on domain types, because any typmod
+ * coercion for a domain is considered to be part of the type coercion
+ * needed to produce the domain value in the first place.
  */
 Node *
 coerce_type_typmod(ParseState *pstate, Node *node,
 				   Oid targetTypeId, int32 atttypmod)
 {
-	Oid			baseTypeId;
 	Oid			funcId;
-	int32		domainTypMod;
-
-	/* If given type is a domain, use base type instead */
-	baseTypeId = getBaseTypeTypeMod(targetTypeId, &domainTypMod);
-
-
-	/*
-	 * Use the domain typmod rather than what was supplied if the
-	 * domain was empty.  atttypmod will always be -1 if domains are in use.
-	 */
-	if (baseTypeId != targetTypeId)
-	{
-		Assert(atttypmod < 0);
-		atttypmod = domainTypMod;
-	}
 
 	/*
 	 * A negative typmod is assumed to mean that no coercion is wanted.
@@ -335,7 +345,8 @@ coerce_type_typmod(ParseState *pstate, Node *node,
 	if (atttypmod < 0 || atttypmod == exprTypmod(node))
 		return node;
 
-	funcId = find_typmod_coercion_function(baseTypeId);
+	funcId = find_typmod_coercion_function(targetTypeId);
+
 	if (OidIsValid(funcId))
 	{
 		Const	   *cons;
@@ -348,7 +359,7 @@ coerce_type_typmod(ParseState *pstate, Node *node,
 						 false,
 						 false);
 
-		node = build_func_call(funcId, baseTypeId, makeList2(node, cons));
+		node = build_func_call(funcId, targetTypeId, makeList2(node, cons));
 	}
 
 	return node;
@@ -869,12 +880,15 @@ build_func_call(Oid funcid, Oid rettype, List *args)
 
 /*
  * Create an expression tree to enforce the constraints (if any)
- * which should be applied by the type.
+ * that should be applied by the type.  Currently this is only
+ * interesting for domain types.
  */
-static Node *
-TypeConstraints(Node *arg, Oid typeId)
+Node *
+coerce_type_constraints(ParseState *pstate, Node *arg,
+						Oid typeId, bool applyTypmod)
 {
 	char   *notNull = NULL;
+	int32	typmod = -1;
 
 	for (;;)
 	{
@@ -885,12 +899,13 @@ TypeConstraints(Node *arg, Oid typeId)
 							 ObjectIdGetDatum(typeId),
 							 0, 0, 0);
 		if (!HeapTupleIsValid(tup))
-			elog(ERROR, "getBaseType: failed to lookup type %u", typeId);
+			elog(ERROR, "coerce_type_constraints: failed to lookup type %u",
+				 typeId);
 		typTup = (Form_pg_type) GETSTRUCT(tup);
 
 		/* Test for NOT NULL Constraint */
 		if (typTup->typnotnull && notNull == NULL)
-			notNull = NameStr(typTup->typname);
+			notNull = pstrdup(NameStr(typTup->typname));
 
 		/* TODO: Add CHECK Constraints to domains */
 
@@ -901,20 +916,32 @@ TypeConstraints(Node *arg, Oid typeId)
 			break;
 		}
 
+		Assert(typmod < 0);
+
 		typeId = typTup->typbasetype;
+		typmod = typTup->typtypmod;
 		ReleaseSysCache(tup);
 	}
 
 	/*
+	 * If domain applies a typmod to its base type, do length coercion.
+	 */
+	if (applyTypmod && typmod >= 0)
+		arg = coerce_type_typmod(pstate, arg, typeId, typmod);
+
+	/*
 	 * Only need to add one NOT NULL check regardless of how many 
-	 * domains in the tree request it.
+	 * domains in the stack request it.  The topmost domain that
+	 * requested it is used as the constraint name.
 	 */
-	if (notNull != NULL) {
-		Constraint *r = makeNode(Constraint);
+	if (notNull)
+	{
+		ConstraintTest *r = makeNode(ConstraintTest);
 
-		r->raw_expr = arg;
-		r->contype = CONSTR_NOTNULL;
-		r->name	= notNull; 
+		r->arg = arg;
+		r->testtype = CONSTR_TEST_NOTNULL;
+		r->name	= notNull;
+		r->check_expr = NULL;
 
 		arg = (Node *) r;
 	}