Can I redistribute the binary form of someone's LGPL code compiled with a proprietary compiler which is not included in the operating system?
LGPL 2.1 says:
For an executable, the required form of the "work that uses the Library" must include any data and utility programs needed for reproducing the executable from it. However, as a special exception, the materials to be distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.
It may happen that this requirement contradicts the license restrictions of other proprietary libraries that do not normally accompany the operating system. Such a contradiction means you cannot use both them and the Library together in an executable that you distribute.
Do I have to redistribute the proprietary compiler, too? Of course, I don't have a permission to redistribute the proprietary compiler.