[CMake] Tests with assert and Release build type

[David Cole]

Not only is it possible ... it WILL happen if you use the Microsoft
C++ compiler and try to mix and match Release and Debug compilation
units.

The MS compiler has some very nice memory tracking facilities built
into the Debug runtime libraries, but it is accomplished via different
structs for Debug and Release builds with extra stuff in the Debug
structs.

So allocations from a Debug compilation unit will not be accessed
correctly in a linked-in Release compilation unit when a pointer to it
is passed across the boundary.

You will see access violations and hard crashes happening in builds
from the Microsoft compiler unless you ensure that everything in a
build has matching Debug/Release defines and compiler settings.

It is only safe to mix-n-match if all calls which cross a boundary
between compilation units have NO differences in their struct and
class definitions from an ABI perspective. Since it is difficult to
verify when this is the case (in general) for large C++ projects, it's
best to avoid mixing and matching...


HTH,
David C.



On Wed, Dec 23, 2015 at 8:29 AM, Ruslan Baratov via CMake
<cmake at cmake.org> wrote:
> On 22-Dec-15 04:07, Magnus Therning wrote:
>>
>> Ruslan Baratov writes:
>>
>>> On 20-Dec-15 01:31, Magnus Therning wrote:
>>>>
>>>> Ruslan Baratov writes:
>>>>
>>>>> How about using RelWithDebInfo? See:
>>>>> http://stackoverflow.com/a/28124715/2288008
>>>>
>>>> Hmm, I'm probably missing something but how does that solve the issue
>>>> with some targets requiring NDEBUG to be *undefined* and other targets
>>>> requiring NDEBUG to be defined?
>>>
>>> I don't think that building targets with different NDEBUG values is a
>>> good idea. More correct approach will be to introduce custom macro to
>>> allow checks (i.e. FOO_NDEBUG/FOO_DEBUG).
>>
>> Why not?
>
> It is possible to hit situation when ODR will be violated, e.g. if somebody
> define optional member in structure with "#if defined(NDEBUG)" condition.
> Something like this:
> http://stackoverflow.com/questions/20833226/library-headers-and-define
>
>>
>> /M
>>
>> --
>> Magnus Therning              OpenPGP: 0x927912051716CE39
>> email: magnus at therning.org   jabber: magnus at therning.org
>> twitter: magthe               http://therning.org/magnus
>>
>> We act as though comfort and luxury were the chief requirements of
>> life, when all that we need to make us happy is something to be
>> enthusiastic about.
>>       -- Albert Einstein
>
>
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