[Scons-dev] D Tooling restart

[Gary Oberbrunner]

On Sat, Oct 20, 2012 at 12:01 PM, Gary Oberbrunner <garyo at oberbrunner.com>wrote:


>

> Indeed, if I can figure a way to make even those tools less hard-wired I

> will try (so D and the other compilers can be on more of an even footing).

>


The problem in the current D code comes from trying to replace the linker
(LINKCOM) with the D linker when there are D sources to be linked.  It does
this with an action Generator called setSmartLink, that's supposed to
return the regular linker command unless there are some D sources, in which
case it returns the D linker command.  (The way in which it finds D sources
is to look at the source to each linker source, which is not 100%
errorproof, but it's OK -- that's for another time.)

The problem is how it replaces LINKCOM; on Windows LINKCOM is a ListAction
where one of the actions is a python method -- and this method doesn't
preserve that because it uses the substitution logic, which stringifies it.

So, since Fortran already has this problem (I'll look at how it solves it),
I propose the time-honored method of adding a new level of abstraction in
the linker command.  It should *always* run a generator function.  That
function will iterate through a list of functions provided by each
language, and those languages can inspect the sources and return the actual
linker command to be run if the source list looks like its linker is
needed.  The default, if no language-specific command generator returns a
command, is to just run LINKCOM.  Then we'll need a defined way for
languages to add their linker generator to the master list.  There is still
the problem of what if they conflict; but that seems to be a hard problem
not yet solved by anyone anyway.  (What linker gets used if you have C++
and Fortran?)  We could give a warning and go with the first result, I
suppose.

Does this seem like a reasonable plan?  I haven't looked at the code in
enough detail to know how to do it, but it doesn't seem completely insane.

-- 
Gary
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