| Message ID | 573EF24F.2000205@oracle.com |
|---|---|
| State | New |
| Headers | show |
On 05/20/2016 07:17 AM, Paolo Carlini wrote: > The below passes testing. There are a few minor changes wrt your > suggestions (I think we want & as hint; I disagree; if what the user wanted was a function pointer, there's no reason to use decltype(auto) over plain auto. Much more likely that they meant to capture the (possibly reference) result of a call. > spacing consistent with > typeck2.c; DECL_NAME doesn't seem necessary). I wondered if we want to > tighten the condition consistently with the wording of the error > message, thus patchlet *2 below, which of course also passes testing. No, I don't think there's any way to deduce function type without the initializer having function type. So, the first patch is OK with the message changed to (). Jason
Hi, On 20/05/2016 17:24, Jason Merrill wrote: > On 05/20/2016 07:17 AM, Paolo Carlini wrote: >> The below passes testing. There are a few minor changes wrt your >> suggestions (I think we want & as hint; > > I disagree; if what the user wanted was a function pointer, there's no > reason to use decltype(auto) over plain auto. Much more likely that > they meant to capture the (possibly reference) result of a call. ... ok, if you are sure that the user (ok, novice programmer) will not be puzzled when he will see that decltype (auto) a = foo () also does not work... but I agree hints are hints, will never be 100% correct and informative... >> spacing consistent with >> typeck2.c; DECL_NAME doesn't seem necessary). I wondered if we want to >> tighten the condition consistently with the wording of the error >> message, thus patchlet *2 below, which of course also passes testing. > > No, I don't think there's any way to deduce function type without the > initializer having function type. > > So, the first patch is OK with the message changed to (). Ok. Paolo.
.. shall we fix this in gcc-6-branch too or not? It's just an ICE on invalid but we don't emit any diagnostic before the crash. Thanks, Paolo.
On Wed, Jun 8, 2016 at 4:21 AM, Paolo Carlini <paolo.carlini@oracle.com> wrote: > .. shall we fix this in gcc-6-branch too or not? It's just an ICE on invalid > but we don't emit any diagnostic before the crash. Sure, it should be safe enough. Jason
Index: cp/decl.c =================================================================== --- cp/decl.c (revision 236496) +++ cp/decl.c (working copy) @@ -6609,6 +6609,13 @@ cp_finish_decl (tree decl, tree init, bool init_co adc_variable_type); if (type == error_mark_node) return; + if (TREE_CODE (type) == FUNCTION_TYPE) + { + error ("initializer for %<decltype(auto) %D%> has function type " + "(did you forget the %<&%> ?)", decl); + TREE_TYPE (decl) = error_mark_node; + return; + } cp_apply_type_quals_to_decl (cp_type_quals (type), decl); } Index: testsuite/g++.dg/cpp1y/auto-fn31.C =================================================================== --- testsuite/g++.dg/cpp1y/auto-fn31.C (revision 0) +++ testsuite/g++.dg/cpp1y/auto-fn31.C (working copy) @@ -0,0 +1,7 @@ +// PR c++/70572 +// { dg-do compile { target c++14 } } + +void foo () +{ + decltype (auto) a = foo; // { dg-error "initializer" } +}