gfortran compiler does not work

Hi,

I got problems to install gcc compiler on mac Catalina by terminal as shown below. Also, I tried to use home brew to install the gfortran. Even if I succeeded in installing the gfortran, it still could not work. It always shows error as below. I reinstalled xcode several and it is the latest version.

Anyone can help? Appreciated!

checking build system type... x86_64-apple-darwin19.5.0

checking host system type... x86_64-apple-darwin19.5.0

checking target system type... x86_64-apple-darwin19.5.0

checking for a BSD-compatible install... /usr/bin/install -c

checking whether ln works... yes

checking whether ln -s works... yes

checking for a sed that does not truncate output... /usr/bin/sed

checking for gawk... no

checking for mawk... no

checking for nawk... no

checking for awk... awk

checking for libatomic support... yes

checking for libitm support... yes

checking for libsanitizer support... yes

checking for libvtv support... no

checking for libhsail-rt support... no

checking for libphobos support... no

checking for gcc... gcc

checking whether the C compiler works... no

configure: error: in `/Users/yongjianzhou/build':

configure: error: C compiler cannot create executables

See `config.log' for more details