IIRC, I got around the M:N problem with GNU make by defining a pattern-matching rule to do what I want. For example, I was using yacc, so I did this:
%.tab.h %.tab.c: %.y
stuff
Using pattern matching forces make (GNU make) to correctly treat this as one rule which outputs multiple files, instead of the default of it being multiple rules which each output one file. It's not perfect, but it is a simple fix for some of those issues.
That's actually one rule which applies to multiple targets.
If you run without parallelism (the default, -j1), it'll work fine, since make will run the rule for one target, and then when it comes to the second one, make will notice that it's already up-to-date (based on file timestamp).
If you run with -j4 or something, it make will likely run the rule twice, simultaneously. That may or may not be a bad problem depending on how the rule writes the output file.
EDIT: man I must have really rushed reading your post... as you say, this does appear to be a heuristic for GNU Make when it's a pattern rule. clearly make is tricky and I end up learning stuff every time I use make...
The automake manual has a description of how to get the dependencies right for multiple outputs: http://www.gnu.org/software/automake/manual/html_node/Multip... . (Disclaimer: I'm no expert, and the Make book mentioned elsewhere in this thread may have a better solution.)
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