https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120776
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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Attachment #61842|0 |1
is obsolete| |
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 61885
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61885&action=edit
gcc16-pr120776-wip.patch
Updated WIP patch.
As the expansion-stmt2.C testcase shows, if expansion-init is dependent and
during first tsubst_stmt of it not dependent, those cases seem to work quite
well (will need to work on diagnostics for control-flow-limited statement,
testcase for no labels in the body etc.
Anyway, still have a couple of major issues:
1) the instantiation when not inside of a template works weirdly; this is
because
tsubst_expr has:
else if (local_variable_p (t)
&& ((r = retrieve_local_specialization (t))
|| TREE_CODE (t) == PARM_DECL
|| uses_template_parms (DECL_CONTEXT (t))))
for non-DECL_LOCAL_DECL_P VAR_DECLs without DECL_TEMPLATE_INFO.
The code right now registers local specialization of the
for-range-declaration
(and structured bindings in there if any), but nothing else. As in
non-templates
uses_template_parms (DECL_CONTEXT (t)) is false, it means only
for-range-declaration
is locally specialized and the rest is used directly (except PARM_DECLs).
Now, we want PARM_DECLs and VAR_DECLs defined outside of the
TEMPLATE_FOR_STMT
to map to themselves, but VAR_DECLs defined inside of the TEMPLATE_FOR_STMT
to be
specialized.
Shall I use some flag next to this || uses_template_parms (e.g. instead of
1-bit
scope_chain->expansion_stmt meant primarily for the control-flow-limited
diagnostics
use 2 bits to differentiate between non-template instantiation during
parsing
vs. the rest?
2) from the paper, it is unclear when the lowering of expansion statement needs
to
happen; it says that for-range-declaration is not type dependent if
expansion-init of iterating expansion stmt is not type dependent and I think
I
handle that already doing auto deduction in that case. But is there some
strong
reason why the expansion statement would need to be lowered still when
processing_template_decl? Not really sure how to (partially) instantiate it
in that case
3) the TEMPLATE_FOR_STMT part doesn't have the if (!finish_expansion_stmt
(...)) case
implemented, I guess I can handle it easily, but I'm afraid I don't
understand
how to construct a testcase, where something is only partially instantiated
and the expansion-initializer is still type-dependent during that
instantiation
and it will need another instantiation later on
