| Message ID | b1061ea1-853b-a891-53aa-865cb9ba9af8@oracle.com |
|---|---|
| State | New |
| Headers | show |
| Series | [C++] PR 70808 ("Spurious -Wzero-as-null-pointer-constant for nullptr_t") | expand |
OK. On Tue, Apr 10, 2018 at 2:57 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote: > Hi, > > this isn't a regression, but deciding what we want to do should be easy and > quick enough. The issue is that "mysteriously" we warn > -Wzero-as-null-pointer-constant for: > > decltype( nullptr ) warn = {}; > > and we don't for: > > int* no_warn = {}; > > That's easily explained given the code we have in build_zero_init_1 which > handles types satisfying TYPE_PTR_OR_PTRMEM_P separately from all the other > scalar types, std::nullptr_t included. I think we should resolve the > inconsistency - the below does that without regressions - but frankly, at > first, given the letter of the standard under 11.6/6 about > zero-initialization I expected that we weren't handling types satisfying > TYPE_PTR_OR_PTRMEM_P in a different way, thus something like a sheer > integer_zero_node consistently for all the scalars (which would mean > resolving the inconsistency precisely the other way round). Probably it's a > tricky detail of our internal representations... > > Thanks, Paolo. > > /////////////////// >
On Tue, Apr 10, 2018 at 08:57:22PM +0200, Paolo Carlini wrote: > 2018-04-10 Paolo Carlini <paolo.carlini@oracle.com> > > PR c++/70808 > * g++.dg/warn/Wzero-as-null-pointer-constant-7.C: New. The testcase FAILs in -std=c++98 mode for obvious reasons. I've committed following after testing it with make check-c++-all RUNTESTFLAGS=dg.exp=Wzero-as-null-pointer-constant-7.C 2018-04-11 Jakub Jelinek <jakub@redhat.com> PR c++/70808 * g++.dg/warn/Wzero-as-null-pointer-constant-7.C: Require c++11 effective target. --- gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C (revision 259324) +++ gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C (revision 259325) @@ -1,4 +1,5 @@ // PR c++/70808 +// { dg-do compile { target c++11 } } // { dg-options "-Wzero-as-null-pointer-constant" } int* no_warn = {}; Jakub
Hi, On 11/04/2018 17:57, Jakub Jelinek wrote: > On Tue, Apr 10, 2018 at 08:57:22PM +0200, Paolo Carlini wrote: >> 2018-04-10 Paolo Carlini <paolo.carlini@oracle.com> >> >> PR c++/70808 >> * g++.dg/warn/Wzero-as-null-pointer-constant-7.C: New. > The testcase FAILs in -std=c++98 mode for obvious reasons. Indeed, thanks Jakub and sorry about the stupid mistake. I'm moving the new testcase to g++.dg/cpp0x/Wzero-as-null-pointer-constant-3.C, more consistent with how we placed these testcases in the past. Paolo.
Index: cp/init.c =================================================================== --- cp/init.c (revision 259287) +++ cp/init.c (working copy) @@ -180,7 +180,7 @@ build_zero_init_1 (tree type, tree nelts, bool sta items with static storage duration that are not otherwise initialized are initialized to zero. */ ; - else if (TYPE_PTR_OR_PTRMEM_P (type)) + else if (TYPE_PTR_OR_PTRMEM_P (type) || NULLPTR_TYPE_P (type)) init = fold (convert (type, nullptr_node)); else if (SCALAR_TYPE_P (type)) init = fold (convert (type, integer_zero_node)); Index: testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C =================================================================== --- testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C (nonexistent) +++ testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C (working copy) @@ -0,0 +1,5 @@ +// PR c++/70808 +// { dg-options "-Wzero-as-null-pointer-constant" } + +int* no_warn = {}; +decltype( nullptr ) warn = {};
Hi, this isn't a regression, but deciding what we want to do should be easy and quick enough. The issue is that "mysteriously" we warn -Wzero-as-null-pointer-constant for: decltype( nullptr ) warn = {}; and we don't for: int* no_warn = {}; That's easily explained given the code we have in build_zero_init_1 which handles types satisfying TYPE_PTR_OR_PTRMEM_P separately from all the other scalar types, std::nullptr_t included. I think we should resolve the inconsistency - the below does that without regressions - but frankly, at first, given the letter of the standard under 11.6/6 about zero-initialization I expected that we weren't handling types satisfying TYPE_PTR_OR_PTRMEM_P in a different way, thus something like a sheer integer_zero_node consistently for all the scalars (which would mean resolving the inconsistency precisely the other way round). Probably it's a tricky detail of our internal representations... Thanks, Paolo. /////////////////// /cp 2018-04-10 Paolo Carlini <paolo.carlini@oracle.com> PR c++/70808 * init.c (build_zero_init_1): Handle NULLPTR_TYPE_P being true of the type like TYPE_PTR_OR_PTRMEM_P. /testsuite 2018-04-10 Paolo Carlini <paolo.carlini@oracle.com> PR c++/70808 * g++.dg/warn/Wzero-as-null-pointer-constant-7.C: New.