================ @@ -800,16 +800,24 @@ Print the dynamic type of the result of an expression (gdb) p someCPPObjectPtrOrReference (Only works for C++ objects) +LLDB does this automatically if determining the dynamic type does not require +running the target (in C++, running the target is never needed). This default is +controlled by the `target.prefer-dynamic-value` setting. If that is disabled, it +can be re-enabled on a per-command basis: + .. code-block:: shell - (lldb) expr -d 1 -- [SomeClass returnAnObject] - (lldb) expr -d 1 -- someCPPObjectPtrOrReference + (lldb) settings set target.prefer-dynamic-value no-dynamic-values + (lldb) frame variable -d no-run-target someCPPObjectPtrOrReference + (lldb) expr -d no-run-target -- someCPPObjectPtr -or set dynamic type printing to be the default: +Note that printing of the dynamic type of references is not possible with the +`expr` command. The workaround is to take the address of the reference and +instruct lldb to print the children of the resulting pointer. ---------------- labath wrote:
I spent some time trying to make this work, but I came to the conclusion that this would require a relatively big change in how the expression evaluator works. Because we're creating persistent copies of the expression result, it's not just a matter of getting something to recognise the dynamic type of the result -- we would actually need to determine the dynamic type of the object before we create the copy (so that we copy the entire object) -- and then I guess somehow reset the original (non-dynamic) ValueObject to point to the subobject of the result. And that might be too much work to put on the shoulders of the "use-dynamic" setting? https://github.com/llvm/llvm-project/pull/138538 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
