Re: [MIT-Scheme-devel] locally toggling compiler switches

[Taylor R Campbell]

Plugh.  I implemented what I mentioned in my earlier message -- see
<http://paste.lisp.org/display/39298> for details --, but stumbled
into the problem that the declarations take effect only in the same
block where they were written.  This is because I made blocks inherit
the checks that they should perform from their parents, but the
declarations are not processed until after the children are created
during flow graph generation; see GENERATE/BODY in fggen/fggen.scm.

I see two ways around this.  One would be to change the declaration
processors to operate ex post facto, and propagate changes into the
children of the block.  This has the unfortunate consequence that it
takes time quadratic in the number of blocks.  The other would be to
walk down the tree of blocks once after they have all been
constructed, post-processing the declarations, rather than using the
machinery in fggen/declar.scm.

Or perhaps it would be best to distinguish pre-generation declarations
and post-generation declarations, which requires more machinery in
fggen/declar.scm and two calls in GENERATE/BODY to it instead of one.