[QE-developers] Configuring with IFLAGS Seemingly Breaks Build Process

[Paolo Giannozzi]

(not sure what happened to this message, it was held for approval and 
disappeared when I approved it)

By far the simple way to deal with special values of IFLAGS is to run 
configure, then modify the make.inc file. In your case, after a 'make 
veryclean' (prevents problems with devXlib like the one you encounter), run

./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 
CPP=/opt/homebrew/bin/cpp-15 LIBDIRS=/opt/homebrew/lib

then, in 'make.inc', just add "-I/opt/homebrew/include" to IFLAGS.

Currently "configure" sets IFLAGS to a few needed directories if you did 
not specify it, to whatever you specified in input otherwise. This is 
not a smart choice: input IFLAGS should be prepended to the needed 
directories. Will be fixed soon

Paolo


On 9/13/2025 12:58 AM, James Telzrow wrote:
> Hello,
> 
> I've encountered an error when trying to build pw on macOS 15.6.1 using 
> FFTW3;
> It seems that running the ./configure script with the IFLAGS parameter 
> specified somehow breaks the build process.
> 
> I started by trying to build pw.x using the following command:
> 
>     ./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/
>     opt/homebrew/bin/cpp-15
> 
> 
> but this doesn't find the version of FFTW installed by homebrew, since I 
> see in the ./configure output the message "using internal copy of FFTW" 
> and "FFT_LIBS= " indicating that no FFT library was found.
> Running "make pw.x" afterwards succeeds and I can run PWscf, but I want 
> to build it with FFTW3.
> 
> I first tried to resolve this by including the option LIBDIRS="/opt/ 
> homebrew/lib" in my ./configure command.
> This partially worked, because I saw in the configure script:
> 
>     in /opt/homebrew/lib:  checking for library containing
>     dfftw_execute_dft... -lfftw3
>     -L/opt/homebrew/lib -lfftw3 
> 
> 
> and in the list of libraries that was found I see "FFT_LIBS=-L/opt/ 
> homebrew/lib -lfftw3".
> However this obviously won't work because I'm not including the 
> necessary files from FFTW:
> when I run "make pw", compilation of fft_scalar.FFTW3.f90 fails as follows:
> 
>     gfortran -O3 -g -fallow-argument-mismatch -cpp -D__FFTW3  -I/Users/
>     jamestelzrow/Documents/Junk_Drawer/custom_qe_build/q-e//external/
>     devxlib/src -I. -I/Users/jamestelzrow/Documents/Junk_Drawer/
>     custom_qe_build/q-e//include  -c fft_scalar.FFTW3.f90 -o
>     fft_scalar.FFTW3.o
>     fft_scalar.FFTW3.f90:41:2:
>        41 |
>             |  1
>     Fatal Error: fftw3.f03: No such file or directory
>     compilation terminated.
> 
> 
> While it isn't included in the error messsage, line 40 is "#include 
> "fftw3.f03"".
> Obviously, gfortran needs to include the directory "/opt/homebrew/include".
> It seems that the correct way to do this is to specify "IFLAGS=-I/opt/ 
> homebrew/include" when calling ./configure, as follows:
> 
>     ./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/
>     opt/homebrew/bin/cpp-15 LIBDIRS="/opt/homebrew/lib" IFLAGS="-I/opt/
>     homebrew/include"
> 
> 
> But when running "make pw" afterwards, although all the components of 
> FFTXlib are compiled successfully, compilation of write_upf_new.f90 
> fails as follows:
> 
>     gfortran -O3 -g -fallow-argument-mismatch -cpp -D__FFTW3  -I/Users/
>     jamestelzrow/Documents/Junk_Drawer/custom_qe_build/q-e//external/
>     devxlib/src -I/opt/homebrew/include -I../UtilXlib -I. -c
>     write_upf_new.f90 -o write_upf_new.o
>     write_upf_new.f90:176:2:
>       176 |     INTEGER :: nw, nb
>              |  1  ~~~~~~~~~~~
>     Fatal Error: qe_version.h: No such file or directory
>     compilation terminated.
> 
> 
> Line 175 in this file is #include "qe_version.h".
> As I can see by looking at the output of "make pw" when building with 
> QE's internal copy of FFTW, this gfortran invocation should include "-I/ 
> Users/jamestelzrow/Documents/Junk_Drawer/custom_qe_build/q-e//include", 
> as the header file "qe_version.h" lies in that directory.
> Again, this directory is included when I run "make pw" after configuring 
> using the command
> 
>     ./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/
>     opt/homebrew/bin/cpp-15
> 
> 
> but not when running "make pw" after using the command
> 
>     ./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/
>     opt/homebrew/bin/cpp-15 LIBDIRS="/opt/homebrew/lib" IFLAGS="-I/opt/
>     homebrew/include"
> 
> 
> so it seems to me that including the IFLAGS parameter when calling ./ 
> configure breaks something.
> I tried to resolve this by including "-I/Users/jamestelzrow/Documents/ 
> Junk_Drawer/custom_qe_build/q-e//include" in IFLAGS, running:
> 
>     ./configure --enable-parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/
>     opt/homebrew/bin/cpp-15 LIBDIRS="/opt/homebrew/lib" IFLAGS="-I/opt/
>     homebrew/include -I/Users/jamestelzrow/Documents/Junk_Drawer/
>     custom_qe_build/q-e//include"
> 
> 
> However, when running "make pw" after doing this, compilation of 
> cegterg.f90 fails as follows:
> 
>     gfortran -O3 -g -fallow-argument-mismatch -cpp -D__FFTW3  -I/Users/
>     jamestelzrow/Documents/Junk_Drawer/custom_qe_build/q-e//external/
>     devxlib/src -I/opt/homebrew/include -I/Users/jamestelzrow/Documents/
>     Junk_Drawer/custom_qe_build/q-e//include -I ../../LAXlib -I ../../
>     UtilXlib -I. -c cegterg.f90 -o cegterg.o
>     cegterg.f90:38:7:
>        38 |   USE device_memcpy_m, ONLY : dev_memcpy, dev_memset
>             |       1
>     Fatal Error: Cannot open module file 'device_memcpy_m.mod' for
>     reading at (1): No such file or directory
>     compilation terminated.
> 
> 
> Looking in the "q-e/external/devxlib/src" directory I see the file 
> "device_memcpy_mod.f90" where the "device_memcpy_m" module is defined, 
> but this directory doesn't contain any ".mod" or ".o" files, seemingly 
> indicating that nothing here was compiled.
> However, in the output of "make pw" after running "./configure --enable- 
> parallel=no CC=/opt/homebrew/bin/gcc-15 CPP=/opt/homebrew/bin/ 
> cpp-15" (without any LIBDIRS or IFLAGS parameters) I can see that these 
> files do get compiled, once again making it seem like the build process 
> is broken somehow.
> 
> Is there some other way that I should be trying to build this, or is 
> there a problem with the configuration scripts or makefiles?
> 
> Thank you,
> 
> James Telzrow