I\'ve used rake a bit (a Ruby make program), and it has an option to get a list of all the available targets, eg
> rake --tasks
rake db:charset # ret
Yet another additional answer to above.
tested on MacOSX using only cat and awk on terminal
cat Makefile | awk '!/SHELL/ && /^[A-z]/ {print $1}' | awk '{print substr($0, 1, length($0)-1)}'
will output of the make file like below:
target1
target2
target3
in the Makefile, it should be the same statement, ensure that you escape the variables using $$variable rather than $variable.
Explanation
cat - spits out the contents
| - pipe parses output to next awk
awk - runs regex excluding "shell" and accepting only "A-z" lines then prints out the $1 first column
awk - yet again removes the last character ":" from the list
this is a rough output and you can do more funky stuff with just AWK. Try to avoid sed as its not as consistent in BSDs variants i.e. some works on *nix but fails on BSDs like MacOSX.
More
You should be able add this (with modifications) to a file for make, to the default bash-completion folder /usr/local/etc/bash-completion.d/ meaning when you "make tab tab" .. it will complete the targets based on the one liner script.