[all-commits] [llvm/llvm-project] 0e9879: [lldb] Correctly check and report error states in ...

[Pete Lawrence via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0e9879ed9711ac280c5e1ea47f77a033393d6baa
      https://github.com/llvm/llvm-project/commit/0e9879ed9711ac280c5e1ea47f77a033393d6baa
  Author: Pete Lawrence <plawrence at apple.com>
  Date:   2023-12-12 (Tue, 12 Dec 2023)

  Changed paths:
    M lldb/source/Target/StackFrame.cpp

  Log Message:
  -----------
  [lldb] Correctly check and report error states in StackFrame.cpp (#74414)

This commits fixes a few subtle bugs where the method:
1. Declares a local `Status error` which eclipses the method's parameter
`Status &error`.
- The method then sets the error state to the local `error` and returns
without ever touching the parameter `&error`.
- This effectively traps the error state and its message from ever
reaching the caller.
- I also threw in a null pointer check in case the callee doesn't set
its `Status` parameter but returns `0`/`nullptr`.

2. Declares a local `Status deref_error` (good), passes it to the
`Dereference` method (also good), but then checks the status of the
method's `Status &error` parameter (not good).
- The fix checks `deref_error` instead and also checks for a `nullptr`
return value.
- There's a good opportunity here for a future PR that changes the
`Dereference` method to fold an error state into the `ValueObject`
return value's `m_error` instead of using a parameter.

3. Declares another local `Status error`, which it doesn't pass to a
method (because there isn't a parameter for it), and then checks for an
error condition that never happens.
- The fix just checks the callee's return value, because that's all it
has to go on.
	- This likely comes from a copy/paste from issue 1 above.


rdar://119155810