gcc7 and libgcc7 are indeed for OS X 10.10 and earlier. They are not expected to be compatible with later macOS versions. Use a newer gcc port instead.
The error in the log is:
/usr/bin/clang++ -arch x86_64 -std=gnu++98 -g -DIN_GCC -fno-strict-aliasing -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wno-format -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common -DHAVE_CONFIG_H -DGENERATOR_FILE -fno-PIE -L/opt/local/lib -Wl,-headerpad_max_install_names -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk -no-pie -o build/gencondmd \
build/gencondmd.o ../build-x86_64-apple-darwin20/libiberty/libiberty.a
clang: warning: argument unused during compilation: '-no-pie' [-Wunused-command-line-argument]
Undefined symbols for architecture x86_64:
"_cfun", referenced from:
___cxx_global_var_init in gencondmd.o
"_epilogue_completed", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_finite_math_only", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_fp_int_builtin_inexact", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_peephole2", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_pic", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_rounding_math", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_trapping_math", referenced from:
___cxx_global_var_init in gencondmd.o
"_flag_unsafe_math_optimizations", referenced from:
___cxx_global_var_init in gencondmd.o
"_insn", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_arch_features", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_cmodel", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_fpmath", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_indirect_branch_register", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_isa_flags", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_isa_flags2", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_pmode", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_stack_protector_guard", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_tls_dialect", referenced from:
___cxx_global_var_init in gencondmd.o
"_ix86_tune_features", referenced from:
___cxx_global_var_init in gencondmd.o
"_operands", referenced from:
___cxx_global_var_init in gencondmd.o
"_optimize", referenced from:
___cxx_global_var_init in gencondmd.o
"_ptr_mode", referenced from:
___cxx_global_var_init in gencondmd.o
"_reload_completed", referenced from:
___cxx_global_var_init in gencondmd.o
"_reload_in_progress", referenced from:
___cxx_global_var_init in gencondmd.o
"_rtx_class", referenced from:
___cxx_global_var_init in gencondmd.o
"_target_flags", referenced from:
___cxx_global_var_init in gencondmd.o
"_this_target_flag_state", referenced from:
___cxx_global_var_init in gencondmd.o
"_word_mode", referenced from:
___cxx_global_var_init in gencondmd.o
"_x86_prefetch_sse", referenced from:
___cxx_global_var_init in gencondmd.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [build/gencondmd] Error 1
make[3]: *** Waiting for unfinished jobs....
Nothing in the dependency chain of the subversion port requires any gcc port—not with default variants on macOS 12 anyway.
