Misleading explanation on dependencies

[AdrianWeaver]

In the README.md you wrote

A rule can have dependencies, some stuff to be fulfilled before execution, named pre-requisits.

Then adding :
A pre-requisit can be either a file or another rule. In the last case, the dependency rule is executed first. If the pre-requisit doesn't match neither a file or a target's name, the Makefile halts and prints an error.

That is actually misleading.
The purpose of a makefile is actually to make... well.... files.
So it does not really matter if the dependency is a file or a rule.
In case the dependency is a rule, the rule will be called.
In case the dependency is a file, the makefile will try to find a rule that makes this file. In case such rule does not exist, it will print an error.

[Nuno-Jesus]

I see your point, but It does matter if the name is a target or a file, since it will have different behaviors whenever the file is present or not, as you said.

[AdrianWeaver]

True, however I still find the way you explain it is misleading.
You explain how it works for rules. You should also explain how it works for files instead of saying "if it doesnt match a file or a target's name.
Because it's either another rule (maybe to put in relation with .PHONY) or it's a file.

So saying doesn't match neither a file or a target's name does hide somehow the fact that make will consider anything as a file and try to find a rule for it.

The error printed being "I don't know the rule to make this file I don't know about"

[Nuno-Jesus]

So I am missing the point where I state "Makefiles consider pre-requisits as files." Possible cases:

• The file exists -> if the file hadn't any recent modification since the last build, the pre-requisit is fulfilled and the Makefile goes on to the next pre-requisit (if any)
• The file exists but changed since the last build -> look for a target that matches the file's name to re-build
• The file doesn't exist -> same as before
• The files doesn't exist and there is no target with a matching name -> halt

Is that it?

[AdrianWeaver]

That's it though some conditions there could be packed together