| Message ID | 24d74e87-7b21-0f8f-fe9b-08d0824a2c64@oracle.com |
|---|---|
| State | New |
| Headers | show |
On 04/27/2017 02:02 PM, Paolo Carlini wrote: > ... replying to myself, in practice we could do the below, which > certainly passes testing, and in fact now seems to me even more obvious > than I thought a couple of days ago... I'm insufficiently conceptified to know whether this is safe (but lack of test failure is promising). nathan
OK. On Thu, Apr 27, 2017 at 2:02 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote: > Hi again, > > On 26/04/2017 12:32, Paolo Carlini wrote: >> >> Hi, >> >> in 2013 (2013-09-16) Adam added two slightly obscure functions and I can't >> find much around in terms of rationale, etc: >> >> /* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto', >> 'decltype(auto)' or a concept. */ >> >> bool >> is_auto_or_concept (const_tree type) >> { >> return is_auto (type); // or concept >> } >> >> /* Returns the TEMPLATE_TYPE_PARM in TYPE representing a generic type >> (`auto' or >> a concept identifier) iff TYPE contains a use of a generic type. >> Returns >> NULL_TREE otherwise. */ >> >> tree >> type_uses_auto_or_concept (tree type) >> { >> return find_type_usage (type, is_auto_or_concept); >> } >> >> The latter seems completely unused (it's meant for debugging purposes?); >> the former evidently simply forwards to is_auto, and we end up in the >> front-end with uses of both, which in fact are equivalent, which seems >> weird: IMHO, if they are actually equivalent in our implementation we should >> clearly explain that in the comment and have only one. Or what? > > > ... replying to myself, in practice we could do the below, which certainly > passes testing, and in fact now seems to me even more obvious than I thought > a couple of days ago... > > Thanks, > Paolo. > > /////////////////////
Sorry for not getting back to your original post Paolo. I haven't been picking up mails for a while. On 2017-05-01 16:56, Jason Merrill wrote: > On Thu, Apr 27, 2017 at 2:02 PM, Paolo Carlini > <paolo.carlini@oracle.com> wrote: >> On 26/04/2017 12:32, Paolo Carlini wrote: >>> >>> in 2013 (2013-09-16) Adam added two slightly obscure functions and I >>> can't >>> find much around in terms of rationale, etc: >>> >>> is_auto_or_concept (const_tree type) >>> >>> type_uses_auto_or_concept (tree type) >>> I don't think they were there in the original 2009 version on the old lambdas branch -- but it stagnated somewhat and when I remade it against mainline (4.something) it was around the time that concepts were showing similar semantics (in terms of implicit/abbrievated templates). I made a cardinal sin and introduced an overly-generic function name expecting that a future concepts implementation would need to trigger at the same point of the parse too. I.e. if a concept name or 'auto' is seen we inject an implicit template parameter (or make the "plain" function into a template at that point). That intent was not well documented or published (other than in the API name) and, since -fconcepts is now working without any calls to this function, it's clearly not been necessary or has been more naturally done in a different way. >>> The latter seems completely unused (it's meant for debugging >>> purposes?); >>> Quite possibly for debugging though maybe some refactoring got rid of the need for it and neglected to bin it. >>> the former evidently simply forwards to is_auto, and we end up in the >>> front-end with uses of both, which in fact are equivalent, which >>> seems >>> weird: IMHO, if they are actually equivalent in our implementation we >>> should >>> clearly explain that in the comment and have only one. Or what? >> >> >> ... replying to myself, in practice we could do the below, which >> certainly >> passes testing, and in fact now seems to me even more obvious than I >> thought >> a couple of days ago... >> Definitely OK to bin. No point in having dead or confusing code; it's complicated enough as it is. :)
Index: cp-tree.h =================================================================== --- cp-tree.h (revision 247347) +++ cp-tree.h (working copy) @@ -6161,7 +6161,6 @@ extern void append_type_to_template_for_access_che extern tree convert_generic_types_to_packs (tree, int, int); extern tree splice_late_return_type (tree, tree); extern bool is_auto (const_tree); -extern bool is_auto_or_concept (const_tree); extern tree process_template_parm (tree, location_t, tree, bool, bool); extern tree end_template_parm_list (tree); Index: parser.c =================================================================== --- parser.c (revision 247347) +++ parser.c (working copy) @@ -38791,16 +38791,6 @@ make_generic_type_name () return get_identifier (buf); } -/* Predicate that behaves as is_auto_or_concept but matches the parent - node of the generic type rather than the generic type itself. This - allows for type transformation in add_implicit_template_parms. */ - -static inline bool -tree_type_is_auto_or_concept (const_tree t) -{ - return TREE_TYPE (t) && is_auto_or_concept (TREE_TYPE (t)); -} - /* Add an implicit template type parameter to the CURRENT_TEMPLATE_PARMS (creating a new template parameter list if necessary). Returns the newly created template type parm. */ Index: pt.c =================================================================== --- pt.c (revision 247347) +++ pt.c (working copy) @@ -3489,7 +3489,7 @@ find_parameter_packs_r (tree *tp, int *walk_subtre parameter pack (14.6.3), or the type-specifier-seq of a type-id that is a pack expansion, the invented template parameter is a template parameter pack. */ - if (ppd->type_pack_expansion_p && is_auto_or_concept (t)) + if (ppd->type_pack_expansion_p && is_auto (t)) TEMPLATE_TYPE_PARAMETER_PACK (t) = true; if (TEMPLATE_TYPE_PARAMETER_PACK (t)) parameter_pack_p = true; @@ -24806,7 +24806,7 @@ static int extract_autos_r (tree t, void *data) { hash_table<auto_hash> &hash = *(hash_table<auto_hash>*)data; - if (is_auto_or_concept (t)) + if (is_auto (t)) { /* All the autos were built with index 0; fix that up now. */ tree *p = hash.find_slot (t, INSERT); @@ -25530,7 +25530,7 @@ is_auto (const_tree type) int is_auto_r (tree tp, void */*data*/) { - return is_auto_or_concept (tp); + return is_auto (tp); } /* Returns the TEMPLATE_TYPE_PARM in TYPE representing `auto' iff TYPE contains @@ -25556,26 +25556,6 @@ type_uses_auto (tree type) return find_type_usage (type, is_auto); } -/* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto', - 'decltype(auto)' or a concept. */ - -bool -is_auto_or_concept (const_tree type) -{ - return is_auto (type); // or concept -} - -/* Returns the TEMPLATE_TYPE_PARM in TYPE representing a generic type (`auto' or - a concept identifier) iff TYPE contains a use of a generic type. Returns - NULL_TREE otherwise. */ - -tree -type_uses_auto_or_concept (tree type) -{ - return find_type_usage (type, is_auto_or_concept); -} - - /* For a given template T, return the vector of typedefs referenced in T for which access check is needed at T instantiation time. T is either a FUNCTION_DECL or a RECORD_TYPE.