[kde-solaris] sizeof() doesn't bind to pointers to template parameter types

Adriaan de Groot groot at kde.org
Sat Aug 18 23:03:04 CEST 2007

The following 4-liner causes an assert in Studio 12:

template<typename T> struct Exam {
        static const unsigned int s = sizeof(T*);
} ;

class A;
Exam<A> s;

Replacing sizeof(T*) by sizeof(void*) avoids the assert. I deduce that 
sizeof() doesn't bind properly to the template parameter T. This is annoying, 
especially in WebKit which is full of that kind of template magic. I am 
patching it locally to replace all sizeof(T*) by sizeof(void*) which I'm not 
sure is 100% correct from a C++ standard point of view (ISTR that pointers to 
different types are allowed to be different sizes).

It's a compiler bug, regardless. 

Let's replace the sizeof(T*) with sizeof(PTR_TYPE*) and watch what happens 
with different values for PTR_TYPE -- Bogus, the template type T and void:

-bash-3.00$ CC -DPTR_TYPE=Bogus t.cc
"t.cc", line 2: Error: Bogus is not defined.
"t.cc", line 7:     Where: While specializing "Exam<A*>".

-bash-3.00$ CC -DPTR_TYPE=T t.cc
 >> Assertion:   (../lnk/bind.cc, line 268)
    while processing t.cc at line 7.

-bash-3.00$ CC -DPTR_TYPE=void t.cc

Good, ugly, good.

Since I'm running nv_64 with CC: Sun C++ 5.9 SunOS_i386 2007/05/03 I'm not 
sure if this is worth filing a bug over; it might be fixed already. 

These are your friends - Adem
    GPG: FEA2 A3FE Adriaan de Groot
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