Remark: `lean.cpp` is a total mess at this point. It contains
leftovers from the Lean2 and Lean3 designs, and hacks for supporting
the Lean4 transition.
Remark: this commit introduce memory leaks, but this is just an
intermediate step to get modification objects in Lean.
Recall that, we will eventually remove modification objects from Lean.
We do not try to check whether code generation will succeed or not for
some declaration. In the future, we should probably rename it to
`nocode` or something similar.
cc @kha
- Lean strings (like std::string) may contain null characters. The
codebase was ignoring this issue.
- We now have a wrapper `string_ref` for wrapping Lean string objects in
C++. This wrapper also implements correctly the coercions std::string <-> string_ref.
Remark: I also found a few places where the code relies on the
following property which is not true
Forall s : std::string, std::string(s.c_str()) == s
- `name` object wrapper was assuming that all numerals were small
`nat` values. This is true in most cases, but the system would
crash when processing if it is a big number.
- The commit tries to make sure runtime/util/kernel are correct.
Modules that will be deleted contain many `TODO` comments
indicating they may crash and/or produce incorrect results
when strings contain null characters and numerals are big.
cc @kha
@kha: I thought about using `string` instead of `string_ref`.
We consistently use `std::string`. So, it should be fine, but I
was concerned about code readability.
After we bootstrap Lean4, we will be able to delete `lean::list`
template, and rename `lean::list_ref` to `lean::list`.
I am going to add `pair_ref` for wrapping Lean pair objects.
If we use `lean::string` instead of `lean::string_ref`, then
we should also use `lean::pair` instead of `lean::pair_ref`.
But, there is a problem in this case since we have
https://github.com/leanprover/lean4/blob/master/src/util/pair.h#L13
:(
The `quot` type is now implemented in the kernel.
We will do the same thing for inductives.
We will not support normalizer extensions anymore in Lean4.
It doesn't make sense since we settled with 2 extensions: quotients and
inductives. Moreover, any new extension would require substantial
changes (e.g., code generator).
The normalizer_extension feature was useful when we were experimenting
with different kernel flavors.
