snprintf assert is broken by plpgsql #option dump

Hi

Today I had broken plpgsql_check tests aganst PostgreSQL 12. After command

create or replace function ml_trg()
returns trigger as $$
#option dump
declare
begin
if TG_OP = 'INSERT' then
if NEW.status_from IS NULL then
begin
-- performance issue only
select status into NEW.status_from
from pa
where pa_id = NEW.pa_id;
-- nonexist target value
select status into NEW.status_from_xxx
from pa
where pa_id = NEW.pa_id;
exception
when DATA_EXCEPTION then
new.status_from := 'DE';
end;
end if;
end if;
if TG_OP = 'DELETE' then return OLD; else return NEW; end if;
exception
when OTHERS then
NULL;
if TG_OP = 'DELETE' then return OLD; else return NEW; end if;
end;
$$ language plpgsql;

I got backtrace:
Program received signal SIGABRT, Aborted.
0x00007f2c140e653f in raise () from /lib64/libc.so.6
(gdb) bt
#0 0x00007f2c140e653f in raise () from /lib64/libc.so.6
#1 0x00007f2c140d0895 in abort () from /lib64/libc.so.6
#2 0x00000000008b7903 in ExceptionalCondition
(conditionName=conditionName(at)entry=0xb00d3b "!(strvalue != ((void *)0))",
errorType=errorType(at)entry=0x906034 "FailedAssertion",
fileName=fileName(at)entry=0xb00d30 "snprintf.c",
lineNumber=lineNumber(at)entry=674) at assert.c:54
#3 0x00000000008ff368 in dopr (target=target(at)entry=0x7fff4ff6aad0,
format=0x7f2bfe4b0de3 " fields",
format(at)entry=0x7f2bfe4b0dda "ROW %-16s fields",
args=args(at)entry=0x7fff4ff6ab18)
at snprintf.c:674
#4 0x00000000008ff6b7 in pg_vfprintf (stream=<optimized out>,
fmt=fmt(at)entry=0x7f2bfe4b0dda
"ROW %-16s fields",
args=args(at)entry=0x7fff4ff6ab18) at snprintf.c:261
#5 0x00000000008ff7ff in pg_printf (fmt=fmt(at)entry=0x7f2bfe4b0dda "ROW
%-16s fields") at snprintf.c:286
#6 0x00007f2bfe4a7c67 in plpgsql_dumptree (func=func(at)entry=0x26811e8) at
pl_funcs.c:1676
#7 0x00007f2bfe49a136 in do_compile (fcinfo=fcinfo(at)entry=0x7fff4ff6afa0,
procTup=procTup(at)entry=0x7f2bfe4ba100, function=0x26811e8,
function(at)entry=0x0, hashkey=hashkey(at)entry=0x7fff4ff6ad20,
forValidator=forValidator(at)entry=true) at pl_comp.c:794
#8 0x00007f2bfe49a27a in plpgsql_compile (fcinfo=fcinfo(at)entry=0x7fff4ff6afa0,
forValidator=forValidator(at)entry=true) at pl_comp.c:224
#9 0x00007f2bfe497126 in plpgsql_validator (fcinfo=<optimized out>) at
pl_handler.c:504
#10 0x00000000008c03df in OidFunctionCall1Coll
(functionId=functionId(at)entry=13392,
collation=collation(at)entry=0, arg1=arg1(at)entry=40960)
at fmgr.c:1418
#11 0x0000000000563444 in ProcedureCreate (procedureName=<optimized out>,
procNamespace=procNamespace(at)entry=2200,
replace=<optimized out>, returnsSet=<optimized out>,
returnType=<optimized out>, proowner=16384, languageObjectId=13393,
languageValidator=13392,
prosrc=0x264feb8 "\n#option

There are new assert

Assert(strvalue != NULL);

probably all refname usage inside plpgsql dump functions has problem with
it.

I found two parts

diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index b93f866223..d97997c001 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -1519,7 +1519,7 @@ dump_execsql(PLpgSQL_stmt_execsql *stmt)
dump_ind();
printf(" INTO%s target = %d %s\n",
stmt->strict ? " STRICT" : "",
- stmt->target->dno, stmt->target->refname);
+ stmt->target->dno, stmt->target->refname ?
stmt->target->refname : "null");
}
dump_indent -= 2;
}
@@ -1673,7 +1673,7 @@ plpgsql_dumptree(PLpgSQL_function *func)
PLpgSQL_row *row = (PLpgSQL_row *) d;
int i;

- printf("ROW %-16s fields", row->refname);
+ printf("ROW %-16s fields", row->refname ? row->refname
: "null");
for (i = 0; i < row->nfields; i++)
{
printf(" %s=var %d", row->fieldnames[i],

Regards

Pavel