[Lldb-commits] [lldb] [LLDB] Add type casting to DIL, part 1 of 3. (PR #165199)

[Ilia Kuklin via lldb-commits]

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@@ -608,4 +608,16 @@ Interpreter::Visit(const BooleanLiteralNode *node) {
   return ValueObject::CreateValueObjectFromBool(m_target, value, "result");
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+Interpreter::Visit(const CStyleCastNode *node) {
+  auto operand_or_err = Evaluate(node->GetOperand());
+  if (!operand_or_err)
+    return operand_or_err;
+
+  lldb::ValueObjectSP operand = *operand_or_err;
+  // Don't actually do the cast for now -- that code will be added later.
+  // For now just return the original operand, unchanged.
+  return operand;
----------------
kuilpd wrote:

> Even `dwim-print` requires context in this regard. After all, an -> access of a value that has an -> overload is going to be different in dwim-print. That command works for common cases but really does require the user to know what they are doing, since there will be cases where both `frame var` and `expr` return valid but different results.
> So it seems to me we should be careful of anything we say or do that confuses the two.

I haven't really thought about that. We already replaced old `frame var` with DIL, which is fine for now since it has basically the same functionality, but will become more of a problem as we add more operators. Compared to `dwim-print`, lldb-dap doesn't do any checks and just tries to use `frame var` for expressions, which means this was an existing problem when a `->` appeared. Even with the old implementation, the overloaded operator wouldn't be used.

I guess we'll have to think again if this was a correct approach to replace `frame var`, or if we should just add the same guards `dwim-print` does to lldb-dap. But I personally really hoped this would just speed up expression evaluation for everyone.

Also, in DIL we could potentially implement overloaded operators, at least with ABI calls, I don't know how limited or accurate this would be though.

https://github.com/llvm/llvm-project/pull/165199