Here are the main (theologically incorrect) arguments commonly used in an attempt to support belief in baptism of desire or baptism of blood.
Denial of any part of the dogmatic Magisterium is a denial of divine and catholic Faith, is heresy.
So it doesn't matter if no pope ever said "We decree and define that 'baptism of desire' is a heresy". All that matters is that the Councils of Vienne, Florence and Trent stated that without the sacrament of Holy Baptism a person cannot enter heaven. Do not recede from those definitions.