[lldb] Print children-count warning for dwim-print and expr (#149088)

When dumping variables, LLDB will print a one-time warning about
truncating children (when the children count exceeds the default
`target.max-children-count`). But we only do this for `frame variable`.
So if we use `dwim-print` or `expression`, the output gets truncated but
we don't print a warning. But because we store the fact that we
truncated some output on the `CommandInterpreter`, we fire the warning
next time we use `frame variable`. E.g.,:
```
(lldb) p arr
(int[1000]) {
  [0] = -5
  [1] = 0
  [2] = 0
  <-- snipped -->
  [253] = 0
  [254] = 0
  [255] = 0
  ...
}
(lldb) v someLocal
(int) someLocal = 10
*** Some of the displayed variables have more members than the debugger
will show by default. To show all of them, you can either use the
--show-all-children option to frame variable or raise the limit by
changing the target.max-children-count setting.
```

This patch prints the warning for `dwim-print` and `expression`.

I only added a test for the `target.max-children-count` for now because
it seems the `target.max-children-depth` warning is broken (I can't get
it to fire).

1 files changed, 3 insertions, 0 deletions

diff --git a/lldb/source/Commands/CommandObjectExpression.cpp b/lldb/source/Commands/CommandObjectExpression.cpp
index a95dea6..c5b9167 100644
--- a/lldb/source/Commands/CommandObjectExpression.cpp
+++ b/lldb/source/Commands/CommandObjectExpression.cpp
@@ -470,6 +470,9 @@ bool CommandObjectExpression::EvaluateExpression(llvm::StringRef expr,
           return false;
         }
 
+        m_interpreter.PrintWarningsIfNecessary(result.GetOutputStream(),
+                                               m_cmd_name);
+
         if (suppress_result)
           if (auto result_var_sp =
                   target.GetPersistentVariable(result_valobj_sp->GetName())) {