Look at how llvm forced gcc to improve their error messages (among other things). Running a different compiler is also useful to find bugs in your project, and

Look at how llvm forced gcc to improve their error messages (among other things). Running a different compiler is also useful to find bugs in your project, and in the compiler itself. I would imagine this applies to the web just as well — a web browser implements an open spec (just like a C++ compiler), at the same time being much more complicated than a C++ compiler.