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<p class="MsoNormal"><span style="font-size:11.0pt">I have been troubleshooting the compilation of WIEN2k on a new workstation using the ifx compiler. The main issue I was having was related to compilation errors in 3ddens as well as in lapw1, but the lapw1
compilation errors only occurred when I attempted to link ELPA. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The cause of the compilation errors was FFTW. The configure script included with FFTW version 3.3.10 is not compatible with the new Intel compilers (icx/ifx etc.) unless an additional step is taken; otherwise,
icx is unable to link FFTW to the applicable Fortran libraries. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">To fix this issue, the FFTW configure script must be updated using autoconf version 2.70 or greater by running the command “autoreconf -if” in the directory where the FFTW tarball was extracted. Once I did
this, recompiled FFTW, and then recompiled WIEN2k, there were no compilation errors for 3ddens and lapw1 with ELPA.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">This is documented in the ifx release notes (<a href="https://www.intel.com/content/www/us/en/developer/articles/release-notes/fortran-compiler/2025.html">https://www.intel.com/content/www/us/en/developer/articles/release-notes/fortran-compiler/2025.html</a>):<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:11.0pt">Configure Script Reports: "linking to Fortran libraries from C fails"</span></b><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:11.0pt">Symptom</span></b><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">When compiling with ifx, a ./configure script generated by GNU Autconf reports an error message similar to:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt"> checking for Fortran 77 libraries of ifx... -loopopt=0 -L/lib/../lib64 -L/lib/../lib64/ -L/usr/lib/../lib64 -L/usr/lib/../lib64/ -L/lib64 -L/lib/ -L/usr/lib64 -L/usr/lib -lifport
-lifcoremt -limf -lsvml -lm -lipgo -lirc -lpthread -lirc_s -ldl<br>
configure: WARNING: FLIBS does not work<br>
checking for ifx flag to add single underscore to external names... none<br>
checking for dummy main to link with Fortran 77 libraries... unknown<br>
configure: error: in '/path/to/build/dir':<br>
configure: error: linking to Fortran libraries from C fails<br>
See `config.log' for more details<br>
make: *** [build/config.status] Error 1<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">Examining the config.log file shows that the error causing ./configure to exit was:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt"> ld: cannot find -loopopt=0<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:11.0pt">Problem </span></b><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">In trying to determine libraries needed to link Fortran code with C or C++ code, GNU Autoconf 2.69 and earlier mistakenly interprets -loopopt=0 in -mllvm -loopopt=0 in verbose compiler
output as a linker flag. GNU Autoconf then adds -loopopt=0 to the FLIBS variable, which is passed to the linker. The linker then looks for a non-existent library causing the test to fail.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:11.0pt">Solution for Users Downloading Source Code</span></b><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">Please inform the maintainers of packages impacted by this error about the problem and refer them to this release note. Projects vary in how they handle configure scripts; however,
some general rules apply. Users who need a solution before the package maintainer can respond can update the configure script themselves. The difficulty of updating depends on how the package is distributed.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">To update, first, install GNU Autoconf-2.70 or newer, as described in
<a href="https://www.intel.com/content/www/us/en/developer/articles/release-notes/fortran-compiler/2025.html#solution-for-package-maintainers">
Solution for Package Maintainers</a>, below.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">After installing the updated autoconf in the user's path, packages that distribute the configure.ac file along with the configure script can be updated simply by running:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt"> autoreconf -if<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">The resulting configure script should be completed without the above error in FLIBS.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">It is not uncommon for project maintainers to remove the configure.ac file from a source distribution in a tar or zip archive. In that case, the user usually needs to download the
project from its code repository, and build according to the project's instructions. Sometimes a version of the configure script is committed to version control and not automatically regenerated. In that case, either running autoreconf -if as described above,
or deleting the configure script often triggers it to be regenerated. Ideally, documentation for the project will describe how to rebuild the configure script.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:11.0pt">Solution for Package Maintainers</span></b><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt">To prevent users from seeing errors, update to GNU Autoconf to version 2.70 or later and re-generate the project configure script. GNU Autoconf-2.70 was
<a href="https://lists.gnu.org/archive/html/autotools-announce/2020-12/msg00001.html">
released </a>December 8, 2020. The source code is available via git clone: http://git.sv.gnu.org/r/autoconf.git. GNU Autoconf documentation is available through
<a href="https://www.gnu.org/software/autoconf/">GNU Autoconf Project Page</a>.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><span style="font-size:11.0pt;mso-ligatures:none"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Daniel Straus<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Assistant Professor<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Department of Chemistry<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Tulane University<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">5088 Percival Stern Hall<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">6400 Freret Street<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">New Orleans, LA 70118<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">(504) 862-3585<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><a href="http://straus.tulane.edu/"><span style="color:#0563C1">http://straus.tulane.edu/</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:11.0pt"><o:p></o:p></span></p>
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