A way to see wxString of wxWidgets 2.9.2 with gdb ?

[Feneck91]

Hello.

Since I began to work with wxWidgets 2.9.2 I cannot see wxString with the gdb debugger, it was working with wxWidgets 2.8.x but wxString code has changed and the gdb_types.script is not working with this new wxString code.

I have tryed to modify gdb_types.script but for the moment, I cannot found a way to make it work.
Any idea ?

[ollydbg]

The best way should use a python enabled gdb, and use the pretty printer for wxString script.
Note the wx pretty printer should be available from:
http://svn.wxwidgets.org/viewvc/wx/wxWidgets/trunk/misc/gdb/print.py

see below as a reference:
http://code.google.com/p/qp-gcc/wiki/GDB
http://wxwidgets.blogspot.com/2009/01/pretty-printing-wxstuff-in-gdb.html

also, As I know, pcx's 4.6.1 mingw has the latest gdb
http://code.google.com/p/pcxprj/downloads/list

[Feneck91]

It's seems to be a litle bit more complex that I could read.
The video http://people.redhat.com/ebachalo/video/archer-pretty-printing-no-audio.swf is no more avalaible.
In downloaded file stdcxx_and_wx_pythonscript.7z, when I decompress, in wx folder I can see libwx\v28\: is this files are really working with wxWidgets 2.9 ?
I use gdb 7.2, should I use C:\MinGW\bin\gdb.exe or C:\MinGW\bin\gdb-python27.exe as debugger ?
gdb-python27.exe cannot be run because python dll is missing, so I have download and install python-2.7.2.msi here,  gdb-python27.exe could now be run.
In settings/compiler and debugger/debugger settings I put 2 lines :

source C:\MinGW\bin\stl.gdb
source C:\MinGW\bin\wx.gdb

Where should I put the file print.py ?

Will test and try to make it work. Will edit this message each time I'll make a step to explain exactly what I need to do to make it work.

[ollydbg]

In downloaded file stdcxx_and_wx_pythonscript.7z, when I decompress, in wx folder I can see libwx\v28\: is this files are really working with wxWidgets 2.9 ?

I have never used wx 2.9, so I can't say much, as I said before, you need the wx python script from the wx trunk:
http://svn.wxwidgets.org/viewvc/wx/wxWidgets/trunk/misc/gdb/print.py
I suggest you can just put the contents of the print.py to PathToYourMinGw\bin\libwx\v28\printers.py

the last change is just use pcx's new 4.6.1 packages. and put the code:

Code

source $(TARGET_COMPILER_DIR)bin\stl.gdb
source $(TARGET_COMPILER_DIR)bin\wx.gdb

in your c::b's debugger's initial command edit control.

[Feneck91]

When I load gdb-python27.exe in place of gdb.exe (in toolchain executable) it seems to change some things.
One example : on breakpoint in "bool wxXmlResource::Load(const wxString& filemask_)"

Code

bool wxXmlResource::Load(const wxString& filemask_)
{
    wxString filemask = ConvertFileNameToURL(filemask_);

    bool allOK = true;

#if wxUSE_FILESYSTEM
    wxFileSystem fsys;
#   define wxXmlFindFirst  fsys.FindFirst(filemask, wxFILE)
#   define wxXmlFindNext   fsys.FindNext()
#else
#   define wxXmlFindFirst  wxFindFirstFile(filemask, wxFILE)
#   define wxXmlFindNext   wxFindNextFile()
#endif
    wxString fnd = wxXmlFindFirst;
    if ( fnd.empty() )
    {
        wxLogError(_("Cannot load resources from '%s'."), filemask);
        return false;
    }

With tooltip on filemask_ indicate "m_impl = L<error reading variable>"
Tooltip on filemask indicate "No symbol "wxStringData" in current context"
Two wxString that not indicate the same thing, strange.
In debugger (add watch) filemask_ indicate : Attemps to take contents of a non-pointer value.
In debugger (add watch) filemask indicate : "" and it is not true.
 If I run GDB in place of gdb-python27.exe, the tooltip of filemask_ indicate the expand of all the class.

For the moment, it don't work !  
I'm sure some other developpers have already test and make debug with wxWidgets 2.9.x under gdb/CodeBlocks, or I am alone in the earth ?

print.py is automatically loaded ? Strange, I don't understand how it is loaded.

[ollydbg]

I have just take several hours to build a wx 2.9.2 under pcx's mingw 4.6.1 then try to see whether it works on wxWidgets.
it seems that you need to change the file:
MinGW_gcc4.6.1release_static_win32\bin\libwx\v28\printers.py

Then use the content below for the wxString class:

Code

# shamelessly stolen from std::string example
@register_pretty_printer
class wxStringPrinter:
    
    regex = re.compile('^wxString$$');
    @static
    def supports(typename):
        return wxStringPrinter.regex.search(typename)
    @static
    def is_undefine(val):
        try:
            val['m_impl']['_M_dataplus']['_M_p'].string()
            return True
        except:
            return False

    def __init__(self, val):
        self.val = val

    def to_string(self):
        return self.val['m_impl']['_M_dataplus']['_M_p'].string()

    def display_hint(self):
        return 'string'

then, everything works fine.

here is my test debug log:

> p msg
$1 = "wxWidgets 2.9.2-Windows-Unicode build"
>>>>>>cb_gdb:

my test code was just use wx wizard to generate a simple wx smith project.

BTW: I use you command to build the wx library. such as:

Code

echo Add MinGW path
set PATH=D:\code\MinGW_gcc4.6.1release_static_win32\bin;%PATH%
cd wxWidgets-2.9.2\build\msw
mingw32-make -f makefile.gcc MONOLITHIC=1 SHARED=1 UNICODE=1 BUILD=release USE_XRC=1 DEBUG_FLAG=0

But I found that I need to manuall change the setup.h, and un-comment the line: (line 70)

Code

  #define wxDEBUG_LEVEL 0

otherwise, I will have a build error, something like:

Code

undefined reference to `wxTheAssertHandler'

more details can be found:
http://trac.wxwidgets.org/ticket/12626

So, I guess the option :DEBUG_FLAG=0 should not be used.

[theojk]

Hi,

for all those, who dont want to use python:

I have modified the small script from CodeBlocks (10.5) for displaying wxStrings.
The old code located in <path to C::B>/share/CodeBlocks/scripts/gdb_types.script

Code

function Evaluate_wxString(type, a_str, start, count)
{
    local oper = _T(".");

    if (type.Find(_T("*"), false) > 0)
        oper = _T("->");

    local result = _T("output /c ") + a_str + oper + _T("m_pchData[") + start + _T("]@");
    if (count != 0)
        result = result + count;
    else
        result = result + _T("((wxStringData*)") + a_str + oper + _T("m_pchData - 1)->nDataLength");
    return result;
}

doesnt work on wxWidgets 2.9.2 anymore
this code

Code

function Evaluate_wxString(type, a_str, start, count)
{
    local oper = _T(".");

    if (type.Find(_T("*"), false) > 0)
        oper = _T("->");

    local result = _T("output /c *((wxChar *)(") + a_str + oper + _T("fn_str()))@") + a_str + oper + _T("Length()");

    return result;
}

displays the String again.

Hope this helps a little bit.

P.S. dont overwrite the whole file, but only the function Evaluate_wxString.  :wink:

[Manolo]

Hi
Starting with wx 2.9, the wxString internal representation depends on the OS. See
http://docs.wxwidgets.org/trunk/overview_string.html

To get your own OS suitable type, use wxString::wx_str(), which returns a pointer of the needed type.
To get the length (in characters, not chars, no bytes, no etc.) there are three functions: Len(), Length() and length().
If you use Len(), then the compiler knows about it and can use it too. If your code does not, GDB neither.

In Squirrel language, I can't find a way for telling the size of an "external" array. So let's GDB manage it.
Because wxString is moving to use std::string, it seems length() (lower case letter) is available.

With all of this, the Evaluate_wxString function at gdb_types.script would look like:

Code

function Evaluate_wxString(type, a_str, start, count)
{
    local oper = _T(".");

    if (type.Find(_T("*"), false) > 0)
        oper = _T("->");

    local result = _T("output /c ") + a_str + oper + _T("wx_str()") + _T("[") + start + _T("]@");
    if (count != 0)
        result = result + count;
    else
        result = result + a_str + oper + _T("length()");
    return result;
}

Now, the C:B Watches window shows the contents of the wxString type var.
Note the GDB command 'output /c' will treat each character as an integer and display it in 7 bit ASCII or escaped sequences if value>127
So, if your wxString has some characters not representable in 7 bit ASCII, you'll see escaped sequences for them.

N.B.
Looking at wx2.8.12 wxWidgets string.h, I find both functions (wx_str & length) are defined. So this script should work also for [all?] wx 2.8 series.

Regards
Manolo

[theojk]

Its working.   
And so it might be the better way, working on other platforms too.  :wink:

Thank You.

[Feneck91]

It's seems that it doesn't work in wxWidgets 2.9.4 in unicode. Another way ?