Script for determining the correct order of static libraries for GNU ld

order_deps.rb

#!/usr/bin/env ruby

# When passing static libraries to GNU ld, one has to make sure the order is correct or undefined references will occur.
# This is due to the linker reading each static library just once.
# With "--start-group" and "--end-group" this behaviour can be overridden but using these options is discouraged.

# call the linker verbosely and print the correct library order to the shell
# ~> gcc prog.c -static -Wl,--verbose -Wl,-\( -llib1 -llib2 -lrest_of_the_libs -Wl,-\) | ./order_deps.rb

libs = Array.new

ARGF.each_line do |line|
    if line =~ /^\(.*\/lib(.*)\.a\).*o$/
        libs << $~[1]
    end
end

# circular dependencies will still cause the linking process to fail.
# in this case remove these three lines.
libs.reverse!()
libs.uniq!()
libs.reverse!()

libs.each do |lib|
    puts lib
end