New linker in Command Line Tools 16 not working with fortran BLOCK DATA

[luillo76]

Hello,

We've encountered a critical issue with the new linker of CLT16 (version 16.1.0.0.1.1729049160) that prevents proper initialization of BLOCK DATA in Fortran code. This affects software built with the Macports-provided GNU gcc13 compiler.

BLOCK DATA are used to initialize global variables, and its failure to initialize those variables leads to a program crash.

The current workaround is using the -ld_classic linker option. However, this option is deprecated and will be removed in a future release, as described in the Xcode release note ​https://developer.apple.com/documentation/xcode-release-notes/xcode-16-release-notes#Linking.

I've attached a minimal example that reproduces the problem using GNU gcc13 with the following instructions:

gfortran -c bd.f
gfortran -c main.f

ar rv libtest.a bd.o main.o

gfortran -ld_classic -o good.x -L. libtest.a
gfortran -o bad.x -L. libtest.a

Running the two programs, one can see that the BLOCK DATA are not initialised without the option ld_classic,

$ > ./good.x 
   3.7273802569289098        2.8083922366048202     
$ > ./bad.x 
   0.0000000000000000        0.0000000000000000

I'm not sure if this is directly related to Macports, but I suspect it might be connected to how Macports builds GCC. Has anyone else encountered this issue? Are there any known workarounds within the Macports environment?

Thanks.