Are the CC BY-SA 3.0 and BSD-3-clause license compatible?

Code published in the Answers forum is covered by the "Creative Commons Attribution Share Alike 3.0 license", also called "CC BY-SA 3.0":

• https://www.mathworks.com/matlabcentral/content/terms-of-use.html?w.mathworks.com#answers
• https://creativecommons.org/licenses/by-sa/3.0/ :
• Share, adapt, attribution + publish und same license

The code published in the FileExchange uses the "BSD-3-clause license":

• https://www.mathworks.com/matlabcentral/FX_transition_faq.html
• https://opensource.org/licenses/BSD-3-Clause
• Redistribute, include originbal copy right note even if distributed as binary, "no commercials" with the name of the author, use "as-is" and no warranties.

Is it a conflict, if code from the Answers forum is used to improve a FileExchange submission, because the license changes? Must the code be accompanied by both licenses?

Can the license be omitted, when the code is trivial enough? If I suggest in the forum to swap the order of loops, it is not worth to cover this by any license conditions. But if I post a smart piece of code and just want to help the readers and do not want to be mentioned as author, what do I have to do? Can I insert such a line as comment:

% License: Jan-DWYW: Do what you want with this code.
%          Don't blame me and don't mention my name, if your code contains bugs.

Or would this be a conflict with the CC BY-SA 3.0 license, which applies to all contributions in the Answers forum?

The license stuff is important, but a strict application is obscure to me. I get some requests per year, if I allow to use my FileExchange code in a thesis or commercial product (of course I do).

If I post code in the forum, I want the readers to save time, and not to waste time with license considerations.