Re: add Order-only Prerequisites example

[jidanni]

>>>>> "PS" == Paul Smith <address@hidden> writes:
>> A:B C;D
>> A:|B C;D

PS> No.  C will never be run first, before B.  If you enable parallel builds
PS> then B and C might be run at the same time (but B will still be started
PS> first, then C).

I recall someone said that there was no guarantee of order even in the
most vanilla (-non-option) of cases.

OK, I sure hope it will get documented that
A:B C;D
implies that if B fails, C will never get run (or built etc.), and we never 
have to
worry about C getting run first (unless we use some -option.)
I.e., C will only get run after we know the results of B.

PS> In the first example, first B and C will be rebuilt then A will be
PS> rebuilt if either A doesn't exist, OR B or C are newer than A.

PS> In the second example, first B and C will be rebuilt then A will be
PS> rebuilt if A doesn't exist, period.  Since B and C are related to A by
PS> build order ONLY, they are built first BUT they don't play a role in
PS> deciding if A should be rebuilt.

All this I would never have dreamed of an I think examples should be
added to pound it into the users' head.