Deparser: Treat type casts inside "func_expr_windowless" as functions

This is mainly in use for RangeFunction, but the logic in the grammar
here is more broad, allowing type casts to show up in places where
a function call would be expected. Fix by always using the "cast(..)"
syntax in such cases.

src/postgres_deparse.c

@@ -29,6 +29,7 @@ typedef enum DeparseNodeContext {
  DEPARSE_NODE_CONTEXT_CREATE_TYPE,
  DEPARSE_NODE_CONTEXT_ALTER_TYPE,
  DEPARSE_NODE_CONTEXT_SET_STATEMENT,
+ DEPARSE_NODE_CONTEXT_FUNC_EXPR,
  // Identifier vs constant context
  DEPARSE_NODE_CONTEXT_IDENTIFIER,
  DEPARSE_NODE_CONTEXT_CONSTANT
@@ -1782,7 +1783,7 @@ static void deparseFuncExprWindowless(StringInfo str, Node* node)
  deparseSQLValueFunction(str, castNode(SQLValueFunction, node));
  break;
  case T_TypeCast:
- deparseTypeCast(str, castNode(TypeCast, node), DEPARSE_NODE_CONTEXT_NONE);
+ deparseTypeCast(str, castNode(TypeCast, node), DEPARSE_NODE_CONTEXT_FUNC_EXPR);
  break;
  case T_CoalesceExpr:
  deparseCoalesceExpr(str, castNode(CoalesceExpr, node));
@@ -3546,7 +3547,7 @@ static void deparseTypeCast(StringInfo str, TypeCast *type_cast, DeparseNodeCont
 
  Assert(type_cast->typeName != NULL);
 
- if (IsA(type_cast->arg, A_Expr))
+ if (IsA(type_cast->arg, A_Expr) || context == DEPARSE_NODE_CONTEXT_FUNC_EXPR)
  {
  appendStringInfoString(str, "CAST(");
  deparseExpr(str, type_cast->arg);