Pius XII was a heretic. BoD, NFP, and a bunch of materially heretical statements mixed into his Masonic flavoured encyclicals.
Good evening Don. Pope Pius IX did not teach that those who die in invincible ignorance can be saved.
I have gathered together the quotes on the matter, and examined them carefully to see exactly what they did and DIDN'T teach.
Here are my findings.
Also, you may be surprised to learn that both online links to the "Catechism of St. Pius X" teach implicit desire.
Note that being a heretic antipope, Pius XII did not actually canonize Pius X. So Pius X, saint as he may very well be, is not one
canonically.
First, from
here.
29 Q. But if a man through no fault of his own is outside the Church, can he be saved?
A. If he is outside the Church through no fault of his, that is, if he is in good faith, and if he has received Baptism, or at least has the implicit desire of Baptism; and if, moreover, he sincerely seeks the truth and does God's will as best he can such a man is indeed separated from the body of the Church, but is united to the soul of the Church and consequently is on the way of salvation
And from
here.
17 Q: Can the absence of Baptism be supplied in any other way?
A: The absence of Baptism can be supplied by martyrdom, which is called Baptism of Blood, or by an act of perfect love of God, or of contrition, along with the desire, at least implicit, of Baptism, and this is called Baptism of Desire.
If this makes you think that Pius X was a heretic, worry not. He cannot be held accountable for the writings in this catechism and for good reasons that I have had the good fortune of being directed to. Now I direct you to the same information that was bestowed upon me (and greatly alleviated much confusion).
Here it is.