templated cmath function instantiation

[Kurt Garloff <garloff at suse dot de>]

Hi,

compiling my templated C++ numeric library with gcc-3.0.0, I use
-fno-implicit-templates to prevent multiple instantiations and explicitly
instantiate all the templates that are supposed to be in the library.
I stumbled across this:
../lina/bin-ix86/libtbcidouble.so: undefined reference to double
std::__cmath_power<double>(double, unsigned)'

I'm rather sure this is a bug: -fno-implicit-templates is not supposed to
change the underlying C++ std library, is it? 
The compiler probably can't just ignore the flag for included C++ std
headers, but then, those symbols should be (weakly) present in libstdc++.so.
At least for the templates only used internally.

Testcase attached.

garloff@pckurt:~/Physics/numerix-2.0-gcc3/lina/test > g++ -o cmath_pow
cmath_pow.cc -fno-implicit-templates
/tmp/ccW0xLby.o: In function double std::__pow_helper<double>(double, int)':
/tmp/ccW0xLby.o(.gnu.linkonce.t._ZSt12__pow_helperIdET_S0_i+0x22): undefined
reference to double std::__cmath_power<double>(double, unsigned)'
/tmp/ccW0xLby.o(.gnu.linkonce.t._ZSt12__pow_helperIdET_S0_i+0x3f): undefined
reference to double std::__cmath_power<double>(double, unsigned)'
collect2: ld returned 1 exit status

If you define WORKAROUND, it works. gcc-2.95 also works, of course.

I'll submit a gccbug unless somebody explains to me that it's me that's
stupid not the compiler ...
Any chance we get that fixed until 3.0.1?

Regards,
-- 
Kurt Garloff  <garloff@suse.de>                          Eindhoven, NL
GPG key: See mail header, key servers         Linux kernel development
SuSE GmbH, Nuernberg, FRG                               SCSI, Security
/** cmath_pow.cc
 * 
 * Trying to reproduce linking  errors for
 * double std::__cmath_power<double>(double, unsigned)
 * in gcc-3.0.0, if -fno=implicit-templates is used.
 * The flag also affects the internally used (invisible) templates 
 * from the C++ std library :-( and at least std::__cmath_power
 * is missing from libstdc++.so.
 *
 * (c) Kurt Garloff, garloff@suse.de, 2001-06-20, GNU GPL
 * 
 * Compile with g++ -o cmath_pow cmath_pow.cc -fno-implicit-templates
 * 
 */

#include <cstdlib>
#include <cstdio>
#include <cmath>

namespace testns {
template <typename T>
double our_pow (const T v, const int pw)
{
	return std::pow ((double)v, pw);
};
};


// Explicitly instantiate (needed because -fno-implicit-templates)
namespace testns {
template double our_pow<long> (const long, const int);
};

int main (int argc, char* argv[])
{
	long int arg = 2; int pw = 4;
	if (argc >= 2)
		arg = std::atol (argv[1]);
	if (argc >= 3)
		pw = std::atol (argv[2]);
	long int res = (long int) testns::our_pow (arg, pw);
	std::printf ("%li\n", res);
	return 0;
}

// The problem ...
#ifdef WORKAROUND
template double std::__cmath_power<double>(double, unsigned);
#endif

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