unsupportable composite type partition keys

Hi,

It seems to me that we currently allow expressions that are anonymous
and self-referencing composite type records as partition key, but
shouldn't. Allowing them leads to this:

create table foo (a int) partition by list ((row(a, b)));
create table foo1 partition of foo for values in ('(1)'::foo);
create table foo2 partition of foo for values in ('(2)'::foo);
explain select * from foo where row(a) = '(1)'::foo;
ERROR: stack depth limit exceeded

Stack trace is this:

#0 errfinish (dummy=0) at elog.c:442
#1 0x0000000000911a51 in check_stack_depth () at postgres.c:3288
#2 0x00000000007970e6 in expression_tree_mutator (node=0x31890a0,
mutator=0x82095f <eval_const_expressions_mutator>,
context=0x7fff0578ef60) at nodeFuncs.c:2526
#3 0x000000000082340b in eval_const_expressions_mutator
(node=0x31890a0, context=0x7fff0578ef60) at clauses.c:3605
#4 0x000000000079875c in expression_tree_mutator (node=0x31890f8,
mutator=0x82095f <eval_const_expressions_mutator>,
context=0x7fff0578ef60) at nodeFuncs.c:2996
#5 0x000000000082340b in eval_const_expressions_mutator
(node=0x31890f8, context=0x7fff0578ef60) at clauses.c:3605
#6 0x000000000079810c in expression_tree_mutator (node=0x3188cc8,
mutator=0x82095f <eval_const_expressions_mutator>,
context=0x7fff0578ef60) at nodeFuncs.c:2863
#7 0x000000000082225d in eval_const_expressions_mutator
(node=0x3188cc8, context=0x7fff0578ef60) at clauses.c:3154
#8 0x000000000079875c in expression_tree_mutator (node=0x3189240,
mutator=0x82095f <eval_const_expressions_mutator>,
context=0x7fff0578ef60) at nodeFuncs.c:2996
#9 0x000000000082340b in eval_const_expressions_mutator
(node=0x3189240, context=0x7fff0578ef60) at clauses.c:3605
#10 0x000000000082090c in eval_const_expressions (root=0x0,
node=0x3189240) at clauses.c:2265
#11 0x0000000000a75169 in RelationBuildPartitionKey
(relation=0x7f5ca3e479a8) at partcache.c:139
#12 0x0000000000a7aa5e in RelationBuildDesc (targetRelId=17178,
insertIt=true) at relcache.c:1171
#13 0x0000000000a7c975 in RelationIdGetRelation (relationId=17178) at
relcache.c:2035
#14 0x000000000048e0c0 in relation_open (relationId=17178, lockmode=1)
at relation.c:59
#15 0x0000000000a8a4f7 in load_typcache_tupdesc (typentry=0x1c16bc0)
at typcache.c:793
#16 0x0000000000a8a3bb in lookup_type_cache (type_id=17180, flags=256)
at typcache.c:748
#17 0x0000000000a8bba4 in lookup_rowtype_tupdesc_internal
(type_id=17180, typmod=-1, noError=false) at typcache.c:1570
#18 0x0000000000a8be43 in lookup_rowtype_tupdesc (type_id=17180,
typmod=-1) at typcache.c:1656
#19 0x0000000000a0713f in record_cmp (fcinfo=0x7fff0578f4d0) at rowtypes.c:815
#20 0x0000000000a083e2 in btrecordcmp (fcinfo=0x7fff0578f4d0) at rowtypes.c:1276
#21 0x0000000000a97bd9 in FunctionCall2Coll (flinfo=0x2bb4a98,
collation=0, arg1=51939144, arg2=51940000) at fmgr.c:1162
#22 0x00000000008443f6 in qsort_partition_list_value_cmp (a=0x3188c50,
b=0x3188c58, arg=0x2bb46c0) at partbounds.c:1769
#23 0x0000000000af9dc6 in qsort_arg (a=0x3188c50, n=2, es=8,
cmp=0x84439a <qsort_partition_list_value_cmp>, arg=0x2bb46c0) at
qsort_arg.c:132
#24 0x000000000084186a in create_list_bounds (boundspecs=0x3188650,
nparts=2, key=0x2bb46c0, mapping=0x7fff0578f7d8) at partbounds.c:396
#25 0x00000000008410ec in partition_bounds_create
(boundspecs=0x3188650, nparts=2, key=0x2bb46c0,
mapping=0x7fff0578f7d8) at partbounds.c:206
#26 0x0000000000847622 in RelationBuildPartitionDesc
(rel=0x7f5ca3e47560) at partdesc.c:205
#27 0x0000000000a7aa6a in RelationBuildDesc (targetRelId=17178,
insertIt=true) at relcache.c:1172

Also:

create table foo (a int) partition by list ((row(a)));
create table foo1 partition of foo for values in (row(1));
create table foo2 partition of foo for values in (row(2));

explain select * from foo where row(a) = '(1)'::foo;
QUERY PLAN
----------------------------------------------------------
Seq Scan on foo1 foo (cost=0.00..41.88 rows=13 width=4)
Filter: (ROW(a) = '(1)'::foo)
(2 rows)

explain select * from foo where row(a) = '(2)'::foo;
QUERY PLAN
----------------------------------------------------------
Seq Scan on foo2 foo (cost=0.00..41.88 rows=13 width=4)
Filter: (ROW(a) = '(2)'::foo)
(2 rows)

-- another session
explain select * from foo where row(a) = '(1)'::foo;
ERROR: record type has not been registered
LINE 1: explain select * from foo where row(a) = '(1)'::foo;

Attached a patch to fix that.

Thanks,
Amit