Often you have a unique_ptr<T> where T supports LLVM's
casting methods, and you wish to cast it to a unique_ptr<U>.
Prior to this patch, this requires doing hacky things like:
unique_ptr<U> Casted;
if (isa<U>(Orig.get()))
Casted.reset(cast<U>(Orig.release()));
This is overly verbose, and it would be nice to just be able
to use unique_ptr directly with cast and dyn_cast. To this end,
this patch updates cast<> to work directly with unique_ptr<T>,
so you can now write:
auto Casted = cast<U>(std::move(Orig));
Since it's possible for dyn_cast<> to fail, however, we choose
to use a slightly different API here, because it's awkward to
write
if (auto Casted = dyn_cast<U>(std::move(Orig))) {}
when Orig may end up not having been moved at all. So the
interface for dyn_cast is
if (auto Casted = unique_dyn_cast<U>(Orig)) {}
Where the inclusion of `unique` in the name of the cast operator
re-affirms that regardless of success of or fail of the casting,
exactly one of the input value and the return value will contain
a non-null result.
Differential Revision: https://reviews.llvm.org/D31890
llvm-svn: 300098
Fill in omission of `cast_or_null<>` and `dyn_cast_or_null<>` for types
that wrap pointers (e.g., smart pointers).
Type traits need to be slightly stricter than for `cast<>` and
`dyn_cast<>` to resolve ambiguities with simple types.
There didn't seem to be any unit tests for pointer wrappers, so I tested
`isa<>`, `cast<>`, and `dyn_cast<>` while I was in there.
This only supports pointer wrappers with a conversion to `bool` to check
for null. If in the future it's useful to support wrappers without such
a conversion, it should be a straightforward incremental step to use the
`simplify_type` machinery for the null check. In that case, the unit
tests should be updated to remove the `operator bool()` from the
`pointer_wrappers::PTy`.
llvm-svn: 222644
subsequent changes are easier to review. About to fix some layering
issues, and wanted to separate out the necessary churn.
Also comment and sink the include of "Windows.h" in three .inc files to
match the usage in Memory.inc.
llvm-svn: 198685
We don't want cast and dyn_cast to work on temporaries. They don't extend
lifetime like a direct bind to a reference would, so they can introduce
hard to find bugs.
I added tests to make sure we don't regress this. Thanks to Eli Friedman for
noticing this and for his suggestions on how to test it.
llvm-svn: 186559
Additionally, all such cases are handled with no dynamic check.
All `classof()` of the form
class Foo {
[...]
static bool classof(const Bar *) { return true; }
[...]
}
where Foo is an ancestor of Bar are no longer necessary.
Don't write them!
Note: The exact test is `is_base_of<Foo, Bar>`, which is non-strict, so
that Foo is considered an ancestor of itself.
This leads to the following rule of thumb for LLVM-style RTTI:
The argument type of `classof()` should be a strict ancestor.
For more information about implementing LLVM-style RTTI, see
docs/HowToSetUpLLVMStyleRTTI.rst
llvm-svn: 165765
Zachary Turner