commit 4376af40df1
Author: Andrew Dunstan <andrew@dunslane.net>
Date:   Fri Mar 6 09:53:23 2026 -0500

    Allow NULL defaults for pseudo-type parameters in pg_proc.dat
    
    InsertOneProargdefaultsValue() called boot_get_type_io_data() for
    every default value entry, including NULLs.  This failed for types
    not present in the bootstrap TypInfo[] array (such as pseudo-type
    "any"), even though NULL defaults never need a type input function.
    
    Fix by handling NULL defaults separately: look up the type metadata
    (typlen, typbyval, typcollation) from TypInfo or the Typ cache if
    available, so that known types get correct Const node metadata
    matching what the SQL parser would produce.  For types not found
    (e.g. "any" during early bootstrap), fall back to "unknown" type,
    which matches the SQL parser's treatment of untyped NULL literals in
    CREATE FUNCTION ... DEFAULT NULL.
    
    This enables functions with VARIADIC "any" DEFAULT NULL to specify
    their defaults directly in pg_proc.dat, without needing a
    system_functions.sql wrapper.

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index e7699be55aa..f979d44a640 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -772,19 +772,70 @@ InsertOneProargdefaultsValue(char *value)
 		bool		defnull;
 		Const	   *defConst;
 
-		boot_get_type_io_data(argtype,
-							  &typlen, &typbyval, &typalign,
-							  &typdelim, &typioparam,
-							  &typinput, &typoutput,
-							  &typcollation);
-
 		defnull = array_nulls[i];
 		if (defnull)
+		{
+			/*
+			 * For NULL defaults, we need the type metadata (typlen etc)
+			 * but not the I/O functions.  Look up the type if possible;
+			 * if it's not available yet (e.g. pseudo-types not in
+			 * TypInfo[]), fall back to "unknown" type, matching what
+			 * the SQL parser produces for untyped NULL literals.
+			 */
+			bool	found = false;
+
 			defval = (Datum) 0;
+			if (Typ != NIL)
+			{
+				ListCell   *lc;
+
+				foreach(lc, Typ)
+				{
+					struct typmap *ap = lfirst(lc);
+
+					if (ap->am_oid == argtype)
+					{
+						typlen = ap->am_typ.typlen;
+						typbyval = ap->am_typ.typbyval;
+						typcollation = ap->am_typ.typcollation;
+						found = true;
+						break;
+					}
+				}
+			}
+			else
+			{
+				for (int j = 0; j < n_types; j++)
+				{
+					if (TypInfo[j].oid == argtype)
+					{
+						typlen = TypInfo[j].len;
+						typbyval = TypInfo[j].byval;
+						typcollation = TypInfo[j].collation;
+						found = true;
+						break;
+					}
+				}
+			}
+			if (!found)
+			{
+				argtype = UNKNOWNOID;
+				typlen = -2;
+				typbyval = false;
+				typcollation = InvalidOid;
+			}
+		}
 		else
+		{
+			boot_get_type_io_data(argtype,
+								  &typlen, &typbyval, &typalign,
+								  &typdelim, &typioparam,
+								  &typinput, &typoutput,
+								  &typcollation);
 			defval = OidInputFunctionCall(typinput,
 										  DatumGetCString(array_datums[i]),
 										  typioparam, -1);
+		}
 
 		defConst = makeConst(argtype,
 							 -1,	/* never any typmod */