On 6/15/24 10:29 PM, Nathaniel Shead wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
This probably isn't the most efficient approach, since we need to do
name lookup to find deduction guides for a type which will also
potentially do a bunch of pointless lazy loading from imported modules,
but I wasn't able to work out a better approach without completely
reworking how deduction guides are stored and represented.
Indeed. We likely want to find them more directly from the template;
it's not clear to me that DECL_INITIAL is used for TEMPLATE_DECL, or we
could put them in an internal attribute or a separate hash table.
-- >8 --
Deduction guides are represented as 'normal' functions currently, and
have no special handling in modules. However, this causes some issues;
by [temp.deduct.guide] a deduction guide is not found by normal name
lookup and instead all reachable deduction guides for a class template
should be considered, but this does not happen currently.
To solve this, this patch ensures that all deduction guides are
considered exported to ensure that they are always visible to importers
if they are reachable. Another alternative here would be to add a new
kind of "all reachable" flag to name lookup, but that is complicated by
some difficulties in handling GM entities; this may be a better way to
go if more kinds of entities end up needing this handling, however.
Another issue here is that because deduction guides are "unrelated"
functions, they will usually get discarded from the GMF, so this patch
ensures that when finding dependencies, GMF deduction guides will also
have bindings created. We do this in find_dependencies so that we don't
unnecessarily create bindings for GMF deduction guides that are never
reached; for consistency we do this for *all* deduction guides, not just
GM ones.
If you fixed the dependency calculation, why do they also need to be
exported?
Jason
