The problem was in calling GetLoadAddress on a value in the error state, where `ValueObject::GetLoadAddress` could end up accessing the uninitialized "address type" by-ref return value from `GetAddressOf`. This probably happened because each function expected the other to initialize it. We can guarantee initialization by turning this into a proper return value. I've added a test, but it only (reliably) crashes if lldb is built with ubsan.
This PR is in continuation of https://github.com/llvm/llvm-project/pull/136693.
This patch replaces the use of `UINT32_MAX` as the error return value of `GetIndexOfChildWithName` with `llvm::Expected`. # Tasks to do in another PR 1. Replace `CalculateNumChildrenIgnoringErrors` with `CalculateNumChildren`. See [this comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2056319358). 2. Update `lldb_private::formatters::ExtractIndexFromString` to use `llvm::Expected`. See [this comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2054217536). 3. Create a new class which carries both user and internal errors. See [this comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2056439608).
The vast majority of `SyntheticChildrenFrontEnd` subclasses provide children, and as such implement `MightHaveChildren` with a constant value of `true`. This change makes `true` the default value. With this change, `MightHaveChildren` only needs to be implemented by synthetic providers that can return `false`, which is only 3 subclasses.
ValueObject is part of lldbCore for historical reasons, but conceptually
it deserves to be its own library. This does introduce a (link-time) circular
dependency between lldbCore and lldbValueObject, which is unfortunate
but probably unavoidable because so many things in LLDB rely on
ValueObject. We already have cycles and these libraries are never built
as dylibs so while this doesn't improve the situation, it also doesn't
make things worse.
The header includes were updated with the following command:
```
find . -type f -exec sed -i.bak "s%include \"lldb/Core/ValueObject%include \"lldb/ValueObject/ValueObject%" '{}' \;
```
This patch is in preparation for the `__compressed_pair` refactor in
https://github.com/llvm/llvm-project/pull/76756.
This is mostly reviewable now. With the new layout we no longer need to
unwrap the `__compressed_pair`. Instead, we just need to look for child
members. E.g., to get to the underlying pointer of `std::unique_ptr` we
no longer do,
```
GetFirstValueOfCXXCompressedPair(GetChildMemberWithName("__ptr_"))
```
but instead do
```
GetChildMemberWithName("__ptr_")
```
We need to be slightly careful because previously the
`__compressed_pair` had a member called `__value_`, whereas now
`__value_` might be a member of the class that used to hold the
`__compressed_pair`. So before unwrapping the pair, we added checks for
`isOldCompressedLayout` (not sure yet whether folding this check into
`GetFirstValueOfCXXCompressedPair` is better).
Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected This is an NFC change that does not yet add any error handling or change any code to return any errors. This is the second big change in the patch series started with https://github.com/llvm/llvm-project/pull/83501 A follow-up PR will wire up error handling.
This reverts commit 99118c809367d518ffe4de60c16da953744b68b9.
Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected This is an NFC change that does not yet add any error handling or change any code to return any errors. This is the second big change in the patch series started with https://github.com/llvm/llvm-project/pull/83501 A follow-up PR will wire up error handling.