https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99922
--- Comment #2 from Brad Richardson <everythingfunctional at protonmail dot com> --- Output from compiling and running with Intel: [pop-os:~/tmp/c_string_interop] ifort -V Intel(R) Fortran Intel(R) 64 Compiler Classic for applications running on Intel(R) 64, Version 2021.2.0 Build 20210228_000000 Copyright (C) 1985-2021 Intel Corporation. All rights reserved. [pop-os:~/tmp/c_string_interop] ifort -c say_hello_fortran.f90 -o say_hello_fortran.f90.o [pop-os:~/tmp/c_string_interop] icc -c say_hello_c.c -o say_hello_c.c.o [pop-os:~/tmp/c_string_interop] ifort -c main.f90 -o main.f90.o [pop-os:~/tmp/c_string_interop] ifort say_hello_fortran.f90.o say_hello_c.c.o main.f90.o -o main.exe [pop-os:~/tmp/c_string_interop] ./main.exe Hello from Fortran, World!