Many, I'm sure. Most Java from 5 years ago will still compile on newer javac versions, for example.

Not just most, I'm betting the overwhelming majority of Java code will compile. But all popular languages break small things with every release (and this is probably a good thing in the long run), so look hard enough and you're guaranteed to find code that won't work.

For instance, here's the compatibility guide to Java 8: http://www.oracle.com/technetwork/java/javase/8-compatibilit...

C#. Yesterday i rebuild a project (with latest compiler version) that i've created 12 years ago.

Note that C# famously broke backwards compatibility when it added generics. I say "famously" because it opted not to follow Java's type-erasure approach (which was chosen so as to explicitly maintain backwards compatibility), and history seems to agree that the minor amount of pain back then was well worth the improvements that it brought to the language (especially relative to Java).

They also changed the for loop var semantics in C# 5.

There a few other little breaking changes as well.

BASIC. Fortran. Pascal. Oberon. Any language designed to be simple and map well to pseudo-code. Even the source-to-source converters tend to have few problems with those. One of reasons I recommended them for certain projects in the past where longevity and talent were concerns.