"cannot run mixed C/Fortran code"

I found the problem.  /usr/local/lib had old copies of libgfortran* and 
libquadmath* from 2015, and removing these allowed things to proceed. 
The current copies are in /usr/local/gfortran/lib.

That directory contains a lot of old junk; I'll probably find more needs 
to go too.

Duncan Murdoch

After updating to Catalina, I've installed the Xcode command line tools
version 11.4.1, and gfortran 8.2.  When trying to build R, configure dies:

   checking whether gfortran appends underscores to external names... yes
   checking whether gfortran appends extra underscores to external
names... no
   checking whether mixed C/Fortran code can be run... configure:
WARNING: cannot run mixed C/Fortran code
   configure: error: Maybe check LDFLAGS for paths to Fortran libraries?

I don't have LDFLAGS set.  I'm not certain I'm running the right
compilers (I might have old ones that have precedence on the path).  Are
these the versions I should be seeing?

$ clang --version
Apple clang version 11.0.3 (clang-1103.0.32.59)
Target: x86_64-apple-darwin19.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

$ gfortran --version
GNU Fortran (GCC) 8.2.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

If those are the right versions, any other suggestions on how to fix the
configure problem?

Duncan Murdoch

Yes, the old gfortran ~4.8.6 binary can cause this issue. Unfortunately, there isn't an uninstaller. I wrote up some guidelines for removing it here:

https://thecoatlessprofessor.com/programming/cpp/removing-the-old-r-custom-gfortran-4.8.2-binary/

The gist is:

# Download installer into working directory
curl -O http://r.research.att.com/libs/gfortran-4.8.2-darwin13.tar.bz2

# Remove _files_ associated with the binary
for file in $(tar tfz gfortran-4.8.2-darwin13.tar.bz2); do
sudo rm -f /$file; 
done

# Remove empty _folders_ associated with the binary
for folder in $(tar tfz gfortran-4.8.2-darwin13.tar.bz2); do 
sudo rmdir -p /$folder; 
done

# Delete the installer
rm -rf gfortran-4.8.2-darwin13.tar.bz2

Best,

JJB

?On 8/4/20, 11:25 AM, "R-SIG-Mac on behalf of Duncan Murdoch" <r-sig-mac-bounces at r-project.org on behalf of murdoch.duncan at gmail.com> wrote:

    I found the problem.  /usr/local/lib had old copies of libgfortran* and 
    libquadmath* from 2015, and removing these allowed things to proceed. 
    The current copies are in /usr/local/gfortran/lib.

    That directory contains a lot of old junk; I'll probably find more needs 
    to go too.

    Duncan Murdoch

> After updating to Catalina, I've installed the Xcode command line tools
    > version 11.4.1, and gfortran 8.2.  When trying to build R, configure dies:
    > 
    >    checking whether gfortran appends underscores to external names... yes
    >    checking whether gfortran appends extra underscores to external
    > names... no
    >    checking whether mixed C/Fortran code can be run... configure:
    > WARNING: cannot run mixed C/Fortran code
    >    configure: error: Maybe check LDFLAGS for paths to Fortran libraries?
    > 
    > I don't have LDFLAGS set.  I'm not certain I'm running the right
    > compilers (I might have old ones that have precedence on the path).  Are
    > these the versions I should be seeing?
    > 
    > $ clang --version
    > Apple clang version 11.0.3 (clang-1103.0.32.59)
    > Target: x86_64-apple-darwin19.6.0
    > Thread model: posix
    > InstalledDir: /Library/Developer/CommandLineTools/usr/bin
    > 
    > $ gfortran --version
    > GNU Fortran (GCC) 8.2.0
    > Copyright (C) 2018 Free Software Foundation, Inc.
    > This is free software; see the source for copying conditions.  There is NO
    > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    > 
    > If those are the right versions, any other suggestions on how to fix the
    > configure problem?
    > 
    > Duncan Murdoch
    >

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