On 9/28/2014 8:10 AM, Ary Borenszweig wrote:
For me, assert is useless.
We are developing a language using LLVM as our backend. If you give LLVM
something it doesn't like, you get something this:
~~~
Assertion failed: (S1->getType() == S2->getType() && "Cannot create binary
operator with two operands of differing type!"), function Create, file
Instructions.cpp, line 1850.
Abort trap: 6
~~~
That is what the user gets when there is a bug in the compiler, at least when we
are generating invalid LLVM code. And that's one of the good paths, if you
compiled LLVM with assertions, because otherwise I guess it's undefined
behaviour.
What I'd like to do, as a compiler, is to catch those errors and tell the user:
"You've found a bug in the app, could you please report it in this URL? Thank
you.". We can't: the assert is there and we can't change it.
You can hook D's assert and do what you want with it.
Now, this is when you interface with C++/C code. But inside our language code we
always use exceptions so that programmers can choose what to do in case of an
error. With assert you loose that possibility.
If you want to use Exceptions for debugging in your code, I won't try and stop
you. But using them for debugging in official Phobos I strongly object to.
Installing an exception handler is cost-free,
Take a look at the assembler dump from std.file.copy() that I posted in the
other thread.
so I don't see why there is a need
for a less powerful construct like assert.
Exceptions are meant for RECOVERABLE errors. If you're using them instead of
assert for logic bugs, you're looking at undefined behavior. Logic bugs are not
recoverable.
