[Boost-build] renaming/deleting sources doesn't invalidate link

From: Matthew Herrmann (matthew.herrmann_at_[hidden])
Date: 2006-03-30 01:35:29

Hi,

I've noticed that removing a source file doesn't invalidate the link step when 
using 'globbed' sources.

I understand that this is because the build "model" is the current Jamfile, so 
the system loses all knowledge of previous sources after files are moved: 
since all .o files are up-to-date, it reasons that the linked executable must 
be up-to-date too. This is not true if the dependencies going into the link 
have changed, however.

I could see this being solved by the following:

- the generator takes in a bunch of .o files and produces a .a and a .parm 
file.
- gcc is invoked with a bunch of command-line options, including all the files 
to link.
- the .parm file simply contains the command-line options used to produce the 
main target (lib or exe).
- when doing an up-to-date check of a target, if the command-line that would 
be evoked to produce a target does not match the contents of the .parm file, 
delete both files and invalidate the target. Do not simply look at the target 
file's timestamp.

Generalising this, #defines could then also be handled safely since these 
changes would then be reflected in the parameters to the compiler. Further, 
any changes to jamfile link/compile parameters would automatically trigger a 
rebuild of the necessary components.

Is such an approach possible? Should I write this up into a ticket for boost 
build?

-- 
Matthew Herrmann
matthew.herrmann_at_[hidden]
Vice President, Software Architecture
Zomojo Pty Ltd