diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out
index 11e6cd8571..69ea821a0c 100644
--- a/src/test/regress/expected/opr_sanity.out
+++ b/src/test/regress/expected/opr_sanity.out
@@ -19,6 +19,8 @@
 -- Helper functions to deal with cases where binary-coercible matches are
 -- allowed.
 -- This should match IsBinaryCoercible() in parse_coerce.c.
+-- It doesn't currently know about some cases, notably domains, anyelement,
+-- anynonarray, anyenum, or record, but it doesn't need to (yet).
 create function binary_coercible(oid, oid) returns bool as $$
 begin
   if $1 = $2 then return true; end if;
@@ -39,9 +41,11 @@ begin
   return false;
 end
 $$ language plpgsql strict stable;
--- This one ignores castcontext, so it considers only physical equivalence
--- and not whether the coercion can be invoked implicitly.
-create function physically_coercible(oid, oid) returns bool as $$
+-- This one ignores castcontext, so it will allow cases where an explicit
+-- (but still binary) cast would be required to convert the input type.
+-- We don't currently use this for any tests in this file, but it is a
+-- reasonable alternative definition for some scenarios.
+create function explicitly_binary_coercible(oid, oid) returns bool as $$
 begin
   if $1 = $2 then return true; end if;
   if EXISTS(select 1 from pg_catalog.pg_cast where
@@ -1221,7 +1225,7 @@ WHERE d.classoid IS NULL AND p1.oid <= 9999;
 
 -- Check that operators' underlying functions have suitable comments,
 -- namely 'implementation of XXX operator'.  (Note: it's not necessary to
--- put such comments into pg_proc.h; initdb will generate them as needed.)
+-- put such comments into pg_proc.dat; initdb will generate them as needed.)
 -- In some cases involving legacy names for operators, there are multiple
 -- operators referencing the same pg_proc entry, so ignore operators whose
 -- comments say they are deprecated.
@@ -1323,7 +1327,6 @@ WHERE a.aggfnoid = p.oid AND
 (0 rows)
 
 -- Cross-check transfn against its entry in pg_proc.
--- NOTE: use physically_coercible here, not binary_coercible, because
 SELECT a.aggfnoid::oid, p.proname, ptr.oid, ptr.proname
 FROM pg_aggregate AS a, pg_proc AS p, pg_proc AS ptr
 WHERE a.aggfnoid = p.oid AND
@@ -1332,15 +1335,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggtranstype)
-     OR NOT physically_coercible(a.aggtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggtranstype)
+     OR NOT binary_coercible(a.aggtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
  aggfnoid | proname | oid | proname 
 ----------+---------+-----+---------
@@ -1362,7 +1366,8 @@ WHERE a.aggfnoid = p.oid AND
          NOT binary_coercible(p.proargtypes[1], pfn.proargtypes[2]))
      OR (pfn.pronargs > 3 AND
          NOT binary_coercible(p.proargtypes[2], pfn.proargtypes[3]))
-     -- we could carry the check further, but 3 args is enough for now
+     -- we could carry the check further, but 4 args is enough for now
+     OR (pfn.pronargs > 4)
     );
  aggfnoid | proname | oid | proname 
 ----------+---------+-----+---------
@@ -1418,15 +1423,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggmtranstype)
-     OR NOT physically_coercible(a.aggmtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggmtranstype)
+     OR NOT binary_coercible(a.aggmtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
  aggfnoid | proname | oid | proname 
 ----------+---------+-----+---------
@@ -1441,15 +1447,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggmtranstype)
-     OR NOT physically_coercible(a.aggmtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggmtranstype)
+     OR NOT binary_coercible(a.aggmtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
  aggfnoid | proname | oid | proname 
 ----------+---------+-----+---------
@@ -1471,7 +1478,8 @@ WHERE a.aggfnoid = p.oid AND
          NOT binary_coercible(p.proargtypes[1], pfn.proargtypes[2]))
      OR (pfn.pronargs > 3 AND
          NOT binary_coercible(p.proargtypes[2], pfn.proargtypes[3]))
-     -- we could carry the check further, but 3 args is enough for now
+     -- we could carry the check further, but 4 args is enough for now
+     OR (pfn.pronargs > 4)
     );
  aggfnoid | proname | oid | proname 
 ----------+---------+-----+---------
@@ -1503,14 +1511,13 @@ WHERE a.aggfnoid = p.oid AND
 
 -- Check that all combine functions have signature
 -- combine(transtype, transtype) returns transtype
--- NOTE: use physically_coercible here, not binary_coercible, because
 SELECT a.aggfnoid, p.proname
 FROM pg_aggregate as a, pg_proc as p
 WHERE a.aggcombinefn = p.oid AND
     (p.pronargs != 2 OR
      p.prorettype != p.proargtypes[0] OR
      p.prorettype != p.proargtypes[1] OR
-     NOT physically_coercible(a.aggtranstype, p.proargtypes[0]));
+     NOT binary_coercible(a.aggtranstype, p.proargtypes[0]));
  aggfnoid | proname 
 ----------+---------
 (0 rows)
diff --git a/src/test/regress/sql/opr_sanity.sql b/src/test/regress/sql/opr_sanity.sql
index 5bb365e9da..b155d90b11 100644
--- a/src/test/regress/sql/opr_sanity.sql
+++ b/src/test/regress/sql/opr_sanity.sql
@@ -22,6 +22,8 @@
 -- allowed.
 
 -- This should match IsBinaryCoercible() in parse_coerce.c.
+-- It doesn't currently know about some cases, notably domains, anyelement,
+-- anynonarray, anyenum, or record, but it doesn't need to (yet).
 create function binary_coercible(oid, oid) returns bool as $$
 begin
   if $1 = $2 then return true; end if;
@@ -43,9 +45,11 @@ begin
 end
 $$ language plpgsql strict stable;
 
--- This one ignores castcontext, so it considers only physical equivalence
--- and not whether the coercion can be invoked implicitly.
-create function physically_coercible(oid, oid) returns bool as $$
+-- This one ignores castcontext, so it will allow cases where an explicit
+-- (but still binary) cast would be required to convert the input type.
+-- We don't currently use this for any tests in this file, but it is a
+-- reasonable alternative definition for some scenarios.
+create function explicitly_binary_coercible(oid, oid) returns bool as $$
 begin
   if $1 = $2 then return true; end if;
   if EXISTS(select 1 from pg_catalog.pg_cast where
@@ -741,7 +745,7 @@ WHERE d.classoid IS NULL AND p1.oid <= 9999;
 
 -- Check that operators' underlying functions have suitable comments,
 -- namely 'implementation of XXX operator'.  (Note: it's not necessary to
--- put such comments into pg_proc.h; initdb will generate them as needed.)
+-- put such comments into pg_proc.dat; initdb will generate them as needed.)
 -- In some cases involving legacy names for operators, there are multiple
 -- operators referencing the same pg_proc entry, so ignore operators whose
 -- comments say they are deprecated.
@@ -822,7 +826,6 @@ WHERE a.aggfnoid = p.oid AND
     a.aggfinalfn = 0 AND p.prorettype != a.aggtranstype;
 
 -- Cross-check transfn against its entry in pg_proc.
--- NOTE: use physically_coercible here, not binary_coercible, because
 SELECT a.aggfnoid::oid, p.proname, ptr.oid, ptr.proname
 FROM pg_aggregate AS a, pg_proc AS p, pg_proc AS ptr
 WHERE a.aggfnoid = p.oid AND
@@ -831,15 +834,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggtranstype)
-     OR NOT physically_coercible(a.aggtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggtranstype)
+     OR NOT binary_coercible(a.aggtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
 
 -- Cross-check finalfn (if present) against its entry in pg_proc.
@@ -859,7 +863,8 @@ WHERE a.aggfnoid = p.oid AND
          NOT binary_coercible(p.proargtypes[1], pfn.proargtypes[2]))
      OR (pfn.pronargs > 3 AND
          NOT binary_coercible(p.proargtypes[2], pfn.proargtypes[3]))
-     -- we could carry the check further, but 3 args is enough for now
+     -- we could carry the check further, but 4 args is enough for now
+     OR (pfn.pronargs > 4)
     );
 
 -- If transfn is strict then either initval should be non-NULL, or
@@ -903,15 +908,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggmtranstype)
-     OR NOT physically_coercible(a.aggmtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggmtranstype)
+     OR NOT binary_coercible(a.aggmtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
 
 -- Cross-check minvtransfn (if present) against its entry in pg_proc.
@@ -923,15 +929,16 @@ WHERE a.aggfnoid = p.oid AND
      OR NOT (ptr.pronargs =
              CASE WHEN a.aggkind = 'n' THEN p.pronargs + 1
              ELSE greatest(p.pronargs - a.aggnumdirectargs, 1) + 1 END)
-     OR NOT physically_coercible(ptr.prorettype, a.aggmtranstype)
-     OR NOT physically_coercible(a.aggmtranstype, ptr.proargtypes[0])
+     OR NOT binary_coercible(ptr.prorettype, a.aggmtranstype)
+     OR NOT binary_coercible(a.aggmtranstype, ptr.proargtypes[0])
      OR (p.pronargs > 0 AND
-         NOT physically_coercible(p.proargtypes[0], ptr.proargtypes[1]))
+         NOT binary_coercible(p.proargtypes[0], ptr.proargtypes[1]))
      OR (p.pronargs > 1 AND
-         NOT physically_coercible(p.proargtypes[1], ptr.proargtypes[2]))
+         NOT binary_coercible(p.proargtypes[1], ptr.proargtypes[2]))
      OR (p.pronargs > 2 AND
-         NOT physically_coercible(p.proargtypes[2], ptr.proargtypes[3]))
+         NOT binary_coercible(p.proargtypes[2], ptr.proargtypes[3]))
      -- we could carry the check further, but 3 args is enough for now
+     OR (p.pronargs > 3)
     );
 
 -- Cross-check mfinalfn (if present) against its entry in pg_proc.
@@ -951,7 +958,8 @@ WHERE a.aggfnoid = p.oid AND
          NOT binary_coercible(p.proargtypes[1], pfn.proargtypes[2]))
      OR (pfn.pronargs > 3 AND
          NOT binary_coercible(p.proargtypes[2], pfn.proargtypes[3]))
-     -- we could carry the check further, but 3 args is enough for now
+     -- we could carry the check further, but 4 args is enough for now
+     OR (pfn.pronargs > 4)
     );
 
 -- If mtransfn is strict then either minitval should be non-NULL, or
@@ -976,7 +984,6 @@ WHERE a.aggfnoid = p.oid AND
 
 -- Check that all combine functions have signature
 -- combine(transtype, transtype) returns transtype
--- NOTE: use physically_coercible here, not binary_coercible, because
 
 SELECT a.aggfnoid, p.proname
 FROM pg_aggregate as a, pg_proc as p
@@ -984,7 +991,7 @@ WHERE a.aggcombinefn = p.oid AND
     (p.pronargs != 2 OR
      p.prorettype != p.proargtypes[0] OR
      p.prorettype != p.proargtypes[1] OR
-     NOT physically_coercible(a.aggtranstype, p.proargtypes[0]));
+     NOT binary_coercible(a.aggtranstype, p.proargtypes[0]));
 
 -- Check that no combine function for an INTERNAL transtype is strict.