[all-commits] [llvm/llvm-project] 6181f4: [lldb] Retcon SBValue::GetChildAtIndex(synthetic=t...

[Pavel Labath via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6181f4f89d022ebf33ed8a449655347eb1b9b6c0
      https://github.com/llvm/llvm-project/commit/6181f4f89d022ebf33ed8a449655347eb1b9b6c0
  Author: Pavel Labath <pavel at labath.sk>
  Date:   2025-05-20 (Tue, 20 May 2025)

  Changed paths:
    M lldb/include/lldb/API/SBValue.h
    M lldb/source/API/SBValue.cpp
    M lldb/test/API/python_api/sbvalue_synthetic/TestSBValueSynthetic.py
    M lldb/test/API/python_api/sbvalue_synthetic/main.cpp

  Log Message:
  -----------
  [lldb] Retcon SBValue::GetChildAtIndex(synthetic=true) (#140065)

The motivation here is being (un)able to treat pointer values as an
array consistently. This works for pointers to simple/scalar values, but
for aggregates, we get a very surprising result:
- GetChildAtIndex(x, ??, true) returns the `x` child of the zeroth array
member (the one you get by dereferencing the pointer/array) for all `x`
which are smaller than the number of children of that value.
- for other values of `x`, we get `v[x]`, where `v` is treated like a
(C) pointer

This patch reimagines this interface so that the value of `true` always
treats (pointer and array) values as pointers. For `false`, we always
dereference pointers, while in the case of arrays, we only return the
values as far as the array bounds will allow.

This has the potential to break existing code, but I have a suspicion
that code was already broken to begin with, which is why I think this
would be better than introducing a new API and keeping the old (and
surprising) behavior. If our own test coverage is any indication,
breakage should be minimal.



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