werat added a comment.
Thanks for the explanation! But at this point I feel I'm a bit confused about
how it all _supposed_ to work in the current design :)
If I understand correctly, there are four "types" of values from the user (API)
perspective:
1. `ExpressionResult` -- value returned by `SBFrame::EvaluateExpression()`
2. `ExpressionPersistentVariable` -- value created by the expression via `auto
$name = ...` syntax. Can be obtained by `SBFrame::FindValue("$name",
lldb::eValueTypeConstResult)`.
3. "Const value" -- value created by `SBTarget::CreateValueFromData()` or
`SBTarget::CreateValueFromAddress`
4. "Variable reference" -- value returned by `SBFrame::FindVariable()`
For which of these value the following test is supposed to work?
struct Foo { int x; };
Foo* f1 = { .x = 1}
Foo* f2 = { .x = 2} # pseudo-C for simplicity
f1_ref = ... # Get a value that holds the value of `f1` using one of the
four methods described above
print(f1_ref.GetChild(0)) # '1'
f1_ref.SetValueFromCString(frame.FindVariable('f2').value)
print(f1_ref.GetChild(0)) # '2'
My experiments show that it works for "variable references" and "const values"
created by `CreateValueFromAddress` (but _not_ `CreateValueFromData`).
If I understand your comment correctly, you're saying it should work only for
`ExpressionPersistentVariable` values (#2). Is that right?
I don't have the full picture about the internal implementation and all the use
cases, but as a user I would expect it to work for at least #2, #3 and #4.
Afaik there's no API to fully distinguish between these kinds of values, so I
find it confusing why `SBValue::SetData()` would be allowed for some values and
not allowed for others. If I can create a value using `CreateValueFromData` and
then there's a method `SetValueFromCString`, then I don't see why it should not
be allowed (apart from implementation complexity/consistency reasons).
What do you think? How should we proceed with this?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D105470/new/
https://reviews.llvm.org/D105470
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