It isn't about fear, it's because I find longer names to be suggestive of a longer life for the name. Shorter names, abbreviations names, etc., are suggestive of short life, lightweight variables. That's, for example, why ScopeBuffer is spelled out, instead of being SBuf.

And lastly, calling it:
```
opSlice(size_t lowerBound, size_t upperBound)
```
just looks like wordy mc-word excess to me. Consider also that opSlice has a conventional purpose, and is used for exactly that conventional purpose. If it did something surprising, I'd be more inclined to agree that more clues to that would be desirable.

I agree that DMD source code can often be confusing, but I don't agree it is because of short names being used. The code has a particular language style, and names that follow usually predictable patterns, and those predictable patterns help in understanding. For example, the scope variable is always 'sc', and 't' is used for types, etc. I find in reading the code that the predictable patterns help enormously, much more than longer names would.