[lldb-dev] invalid use of 'this' outside of a non-static member function

Zachary Turner zturner at google.com
Wed Jan 7 11:03:08 PST 2015

Other way around actually now that I looked it up, C++ is not the default
mode but can be specified when desired.  Obviously their expression
evaluator is much more limited for other reasons such as not having a full
blown compiler backing it up, but still, something like this is a 3rd
option (choosing a reasonable default and allowing escaping to force
evaluation of certain pieces in another mode)

On Wed Jan 07 2015 at 10:57:30 AM Zachary Turner <zturner at google.com> wrote:

> The canonical Windows command line debugger solves this by having two
> different evaluation modes.  One for C and one for C++.  I believe C++ is
> always the default, but C evaluation mode can be forced by enclosing an
> expression in special delimiters.  You can toggle the evaluation mode
> multiple times inside the same expression as well.  So you can have a
> single expression where different pieces of it are evaluated differently.
> Not a language lawyer, but it seems like other stuff would be broken
> besides just variables named 'this'.  Are there any other known causes of
> incorrect evaluation in C frames due to using a C++ evaluation mode?
> On Wed Jan 07 2015 at 10:51:43 AM Greg Clayton <gclayton at apple.com> wrote:
>> All expressions are compiled in C++ mode and thus the restriction.
>> There are a few solutions:
>> 1 - make expressions match the current language of the current frame. So
>> if your function was a C function, you will be restricted from using C++ in
>> your expression
>> 2 - rename your "this" and benefit from the C++ abilities of the
>> expression parser
>> I personally really like the ability to use "auto" and all of the C++11
>> constructs in any expression:
>> (lldb) expr for (auto x = 0; x < my_renamed_this; ++x) { ... }
>> So I see the problem with C expressions, but I would rather not limit you
>> from being able to access your C++ code from a C function by limiting the
>> language based on where you are stopped.
>> Greg
>> > On Jan 7, 2015, at 7:16 AM, mobi phil <mobi at mobiphil.com> wrote:
>> >
>> > Hi,
>> >
>> > The compiler accepted it, so IMHO LLDB should not complain about it.
>> >
>> > I can rename this "this" inside a C function, but it is very likely
>> that other people would name a variable "this" inside C code.
>> >
>> >
>> > rgrds,
>> > mobi phil
>> >
>> >
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