Re: gcc 9.5.0 compiler error: identifier "__builtin_is_constant_evaluated" is undefined

["Baribault, Carl" <cbaribault@tulane.edu>]

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Hi Jonathan,

Thanks for your reply.

I've installed gcc 9.5.0 on our campus cluster under /share/apps/centos7/gcc/9.5.0.

When I search for that function name among the installed files, I see it used multiple times, but I don't see that function defined anywhere. Please advise, thanks.


$ grep -r __builtin_is_constant_evaluated /share/apps/centos7/gcc/9.5.0

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bit:      if (!__builtin_is_constant_evaluated())

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/x86_64-pc-linux-gnu/bits/c++config.h:# if __has_builtin(__builtin_is_constant_evaluated)

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/type_traits:  { return __builtin_is_constant_evaluated(); }

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/stl_function.h: if (__builtin_is_constant_evaluated())

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/stl_function.h: if (__builtin_is_constant_evaluated())

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/stl_function.h: if (__builtin_is_constant_evaluated())

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/stl_function.h: if (__builtin_is_constant_evaluated())

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/char_traits.h:      return __builtin_is_constant_evaluated();

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/char_traits.h:      return __builtin_is_constant_evaluated();

Binary file /share/apps/centos7/gcc/9.5.0/libexec/gcc/x86_64-pc-linux-gnu/9.5.0/cc1plus matches

Also, here's the error message.


In file included from /share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/ios_base.h(46),

                 from /share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/ios(42),

                 from /share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/ostream(38),

                 from /share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/iostream(39),

                 from pic.cpp(6):

/share/apps/centos7/gcc/9.5.0/include/c++/9.5.0/bits/stl_function.h(437): error: identifier "__builtin_is_constant_evaluated" is undefined

        if (__builtin_is_constant_evaluated())

            ^


compilation aborted for pic.cpp (code 2)

Also, granted this error does not occur compiling pic.cpp using g++, and only occurs using Intel's icpc with GNU/g++ headers.


$ cat pic.cpp

// C++ program to estimate value of pi

// See discussion for Improved Say of Determining Pi at

//  http://mb-soft.com/public3/pi.html  (retrieved March 2017)

// If we integrate 1/(1+x^2) for x=0:1, we get pi/4


#include <iostream>

#include <iomanip>

#include <cstdlib>


using std::cout;


int main(int argc, char* argv[])

{

  long i, nsteps;

  double pi, step, sum = 0.0;

  nsteps = 0;

  if (argc > 1)

    nsteps = atol(argv[1]);

  if (nsteps <= 0)

    nsteps = 100;

  step = (1.0)/((double)nsteps);

  for (i = 0; i < nsteps; ++i) {

    double x = ((double)i+0.5)*step;

    sum += 1.0 / (1.0 + x * x);

  }

  pi = 4.0 * step * sum;

  cout << std::fixed;

  cout << "pi is " << std::setprecision(17) << pi << "\n";

}

________________________________
From: Jonathan Wakely <jwakely.gcc@gmail.com>
Sent: Monday, May 8, 2023 3:05 PM
To: Baribault, Carl <cbaribault@tulane.edu>
Cc: gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: gcc 9.5.0 compiler error: identifier "__builtin_is_constant_evaluated" is undefined


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On Mon, 8 May 2023, 20:00 Baribault, Carl via Gcc-help, <gcc-help@gcc.gnu.org<mailto:gcc-help@gcc.gnu.org>> wrote:
Dear Help,

The subject identifier is nowhere defined.

Please let me know if you need any more information. Thank you.

Yes, we need more info, you've provided none at all.

That is a built-in function provided by the compiler, present since gcc 9.1.0

In what context are you seeing it not defined? What are you trying to do, and what error do you get?






Best,
C. Baribault