Replace SQLValueFunction by COERCE_SQL_SYNTAX

This switch impacts 9 patterns related to a SQL-mandated special syntax
for function calls:
- LOCALTIME [ ( typmod ) ]
- LOCALTIMESTAMP [ ( typmod ) ]
- CURRENT_TIME [ ( typmod ) ]
- CURRENT_TIMESTAMP [ ( typmod ) ]
- CURRENT_DATE

Five new entries are added to pg_proc to compensate the removal of
SQLValueFunction to provide backward-compatibility and making this
change transparent for the end-user (for example for the attribute
generated when a keyword is specified in a SELECT or in a FROM clause
without an alias, or when specifying something else than an Iconst to
the parser).

The parser included a set of checks coming from the files in charge of
holding the C functions used for the SQLValueFunction calls (as of
transformSQLValueFunction()), which are now moved within each function's
execution path, so this reduces the dependencies between the execution
and the parsing steps.  As of this change, all the SQL keywords use the
same paths for their work, relying only on COERCE_SQL_SYNTAX.  Like
fb32748, no performance difference has been noticed, while the perf
profiles get reduced with ExecEvalSQLValueFunction() gone.

Bump catalog version.

Reviewed-by: Corey Huinker, Ted Yu
Discussion: https://postgr.es/m/YzaG3MoryCguUOym@paquier.xyz

1 files changed, 47 insertions, 45 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 129f3333fb9..f3ea36a231c 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -8150,7 +8150,6 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
 		case T_RowExpr:
 		case T_CoalesceExpr:
 		case T_MinMaxExpr:
-		case T_SQLValueFunction:
 		case T_XmlExpr:
 		case T_NextValueExpr:
 		case T_NullIfExpr:
@@ -9130,49 +9129,6 @@ get_rule_expr(Node *node, deparse_context *context,
 			}
 			break;
 
-		case T_SQLValueFunction:
-			{
-				SQLValueFunction *svf = (SQLValueFunction *) node;
-
-				/*
-				 * Note: this code knows that typmod for time, timestamp, and
-				 * timestamptz just prints as integer.
-				 */
-				switch (svf->op)
-				{
-					case SVFOP_CURRENT_DATE:
-						appendStringInfoString(buf, "CURRENT_DATE");
-						break;
-					case SVFOP_CURRENT_TIME:
-						appendStringInfoString(buf, "CURRENT_TIME");
-						break;
-					case SVFOP_CURRENT_TIME_N:
-						appendStringInfo(buf, "CURRENT_TIME(%d)", svf->typmod);
-						break;
-					case SVFOP_CURRENT_TIMESTAMP:
-						appendStringInfoString(buf, "CURRENT_TIMESTAMP");
-						break;
-					case SVFOP_CURRENT_TIMESTAMP_N:
-						appendStringInfo(buf, "CURRENT_TIMESTAMP(%d)",
-										 svf->typmod);
-						break;
-					case SVFOP_LOCALTIME:
-						appendStringInfoString(buf, "LOCALTIME");
-						break;
-					case SVFOP_LOCALTIME_N:
-						appendStringInfo(buf, "LOCALTIME(%d)", svf->typmod);
-						break;
-					case SVFOP_LOCALTIMESTAMP:
-						appendStringInfoString(buf, "LOCALTIMESTAMP");
-						break;
-					case SVFOP_LOCALTIMESTAMP_N:
-						appendStringInfo(buf, "LOCALTIMESTAMP(%d)",
-										 svf->typmod);
-						break;
-				}
-			}
-			break;
-
 		case T_XmlExpr:
 			{
 				XmlExpr    *xexpr = (XmlExpr *) node;
@@ -9698,7 +9654,6 @@ looks_like_function(Node *node)
 		case T_NullIfExpr:
 		case T_CoalesceExpr:
 		case T_MinMaxExpr:
-		case T_SQLValueFunction:
 		case T_XmlExpr:
 			/* these are all accepted by func_expr_common_subexpr */
 			return true;
@@ -10043,6 +9998,33 @@ get_windowfunc_expr(WindowFunc *wfunc, deparse_context *context)
 }
 
 /*
+ * get_func_sql_syntax_time
+ *
+ * Parse back argument of SQL-syntax function call related to a time or a
+ * timestamp.  These require a specific handling when their typmod is given
+ * by the function caller through their SQL keyword.
+ */
+static void
+get_func_sql_syntax_time(List *args, deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+	Const	   *cons;
+
+	if (list_length(args) != 1)
+		return;
+
+	cons = (Const *) linitial(args);
+	Assert(IsA(cons, Const));
+
+	if (!cons->constisnull)
+	{
+		appendStringInfoString(buf, "(");
+		get_rule_expr((Node *) cons, context, false);
+		appendStringInfoString(buf, ")");
+	}
+}
+
+/*
  * get_func_sql_syntax		- Parse back a SQL-syntax function call
  *
  * Returns true if we successfully deparsed, false if we did not
@@ -10292,6 +10274,26 @@ get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
 			appendStringInfoString(buf, "SYSTEM_USER");
 			return true;
 
+		case F_CURRENT_DATE:
+			appendStringInfoString(buf, "CURRENT_DATE");
+			return true;
+		case F_CURRENT_TIME:
+			appendStringInfoString(buf, "CURRENT_TIME");
+			get_func_sql_syntax_time(expr->args, context);
+			return true;
+		case F_CURRENT_TIMESTAMP:
+			appendStringInfoString(buf, "CURRENT_TIMESTAMP");
+			get_func_sql_syntax_time(expr->args, context);
+			return true;
+		case F_LOCALTIME:
+			appendStringInfoString(buf, "LOCALTIME");
+			get_func_sql_syntax_time(expr->args, context);
+			return true;
+		case F_LOCALTIMESTAMP:
+			appendStringInfoString(buf, "LOCALTIMESTAMP");
+			get_func_sql_syntax_time(expr->args, context);
+			return true;
+
 		case F_XMLEXISTS:
 			/* XMLEXISTS ... extra parens because args are c_expr */
 			appendStringInfoString(buf, "XMLEXISTS((");