Category: Programming

Now for something really controversial: what’s wrong with protected symbols? In an ELF shared library, an ordinary global symbol may be overridden if a symbol of the same name is defined in the executable or in a shared library which appears earlier in the runtime search path. This is called symbol interposition. It is often…

I recently spent some time sorting through linker version script issues, so I’m going to document what I discovered. Linker symbol versioning was invented at Sun. The Solaris linker lets you use a version script when you create a shared library. This script assigns versions to specific named symbols, and defines a version hierarchy. When…

I recently encountered a nice example of cargo cult programming. In bug 10980 Robert Wohlrab helpfully built a large number of Debian packages with the gold linker and reported errors about unknown options. These were options supported by the GNU linker but not by gold. (I’ve now added all the options to gold). Among the…

The goal of generics in a programming language is to save programmer time. Generics permit you to write code that works with multiple types only once. They also permit one programmer to write generic algorithms which you can use with your program’s types. This kind of thing is attractive to anybody who has written a…

When writing the gccgo frontend I had to figure out how to write a new gcc frontend. This is a largely undocumented procedure. Unfortunately, I did not take notes as I went along. However, here are some retrospective comments. Every gcc frontend needs a set of language hooks. This is done by including “langhooks-def.h” and…