Here is the compile command and the warning:

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===== Checking linker Executing: gfortran -c -o /var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers/conftest.o -I/var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers /var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers/conftest.F90 Successful compile: Source: function foo(a) real:: a,x,bar common /xx/ x x=a foo = bar(x) end Executing: gcc -o /var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers/libconftest.dylib -dynamiclib -single_module -undefined dynamic_lookup -multiply_defined suppress /var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers/conftest.o Possible ERROR while running linker: stderr: ld: warning: object file (/var/folders/9w/7dlszmmn6q1gd5yf3r9n79bc0000gn/T/petsc-dk9aiv7x/config.setCompilers/conftest.o) was built for newer macOS version (11.2) than being linked (11.0) Accepted FC PIC code without compiler flag ============================================================================================= <<<<<<

Its likely due to the way brew built gfortran. You can try compiling a simple test code and see if you can reproduce this warning. There is a related issue at: https://github.com/spack/spack/issues/21644 Satish On Sat, 13 Feb 2021, Jacob Faibussowitsch wrote:

Hello All,

I’ve been getting these warnings for weeks, at first I figured it was due to gfortran brew package not being updated for Big Sur, but since it has persisted through a few gfortran brew updates I’m thinking it may be petsc related. This is on clean build on master.

ld: warning: object file (master-arch-darwin-c-debug/obj/sys/classes/bag/f2003-src/fsrc/bagenum.o) was built for newer macOS version (11.2) than being linked (11.0) ld: warning: object file (master-arch-darwin-c-debug/obj/sys/f90-src/fsrc/f90_fwrap.o) was built for newer macOS version (11.2) than being linked (11.0) ld: warning: object file (master-arch-darwin-c-debug/obj/sys/objects/f2003-src/fsrc/optionenum.o) was built for newer macOS version (11.2) than being linked (11.0) ld: warning: object file (master-arch-darwin-c-debug/obj/sys/fsrc/somefort.o) was built for newer macOS version (11.2) than being linked (11.0) ld: warning: object file (master-arch-darwin-c-debug/obj/sys/f90-mod/petscsysmod.o) was built for newer macOS version (11.2) than being linked (11.0)

Best regards,

Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) Cell: (312) 694-3391