Re: Hard time figuring out what order-only prerequisites really do.

[Noel Yap]

In my view, all they do is change the meaning of "up to date" from the usual "exists and 
timestamp is newer" to just "exists".

Noel

Angel Tsankov wrote:

> I'm having a really hard time what order-only prerequsites really do.
>
> First, I thought that they will do just fine if I want to have my object 
> files go in a separate folder. This makes it necessary to ensure this folder 
> (let's name it IntemediateFolder) exists before compilation of each source 
> file. Of course, this check should not render the target (object file) 
> out-of-date. As far as I get it all this make the folder-existence check 
> (and creation if necessary) appropriate for an order-only prerequiste. 
> However, I must be awfully wrong, 'cause I could not come up with a makefile 
> that does exactly this. And I've been trying it since for a whole day...
>
> So, I've attached the troublesome makefile. I execute it with make 3.80 on a 
> linux system. Could you explain to me why the script compiles the soruce 
> files even when the objects do exist and are newer than the corresponding 
> source files?
>
> Best wishes,
> An unsuccessful rocket sceintist 
>
>
>
>
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