[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #11 from Jonathan Wakely  ---
That's now PR 85553

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #10 from Jonathan Wakely  ---
This causes a regression for:

using T = decltype(nullptr);
const constexpr T foo{};

np.cc:2:23: error: ‘(const T)nullptr’ is not a constant expression
 const constexpr T foo{};
   ^

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #9 from Jakub Jelinek  ---
Author: jakub
Date: Wed Apr 11 15:55:15 2018
New Revision: 259325

URL: https://gcc.gnu.org/viewcvs?rev=259325=gcc=rev
Log:
PR c++/70808
* g++.dg/warn/Wzero-as-null-pointer-constant-7.C: Require c++11
effective target.

Modified:
trunk/gcc/testsuite/ChangeLog
trunk/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

Paolo Carlini  changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 CC|jason at gcc dot gnu.org,  |
   |paolo.carlini at oracle dot com|
 Resolution|--- |FIXED
   Assignee|paolo.carlini at oracle dot com|unassigned at gcc dot 
gnu.org
   Target Milestone|--- |8.0

--- Comment #8 from Paolo Carlini  ---
Fixed.

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #7 from paolo at gcc dot gnu.org  ---
Author: paolo
Date: Tue Apr 10 22:34:06 2018
New Revision: 259303

URL: https://gcc.gnu.org/viewcvs?rev=259303=gcc=rev
Log:
/cp
2018-04-10  Paolo Carlini  

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  

PR c++/70808
* g++.dg/warn/Wzero-as-null-pointer-constant-7.C: New.

Added:
trunk/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C
Modified:
trunk/gcc/cp/ChangeLog
trunk/gcc/cp/init.c
trunk/gcc/testsuite/ChangeLog

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

Paolo Carlini  changed:

   What|Removed |Added

 Status|NEW |ASSIGNED
   Assignee|unassigned at gcc dot gnu.org  |paolo.carlini at oracle 
dot com

--- Comment #6 from Paolo Carlini  ---
Mine.

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #5 from Paolo Carlini  ---
In fact, there is sort-of an inconsistency in build_zero_init_1 which explains
the inconsistency in the original testcase:

  else if (TYPE_PTR_OR_PTRMEM_P (type))
init = fold (convert (type, nullptr_node));
  else if (SCALAR_TYPE_P (type))
init = fold (convert (type, integer_zero_node));

thus std::nullptr_t is handled as a generic scalar, whereas int* is not.
Changing the above as in the below makes sense to me and would have the effect
of suppressing the warning for both the testcases here.

Index: init.c
===
--- init.c  (revision 259287)
+++ 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));

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

--- Comment #4 from Paolo Carlini  ---
NB: I played only with the *second* testcase, under the assumption that it was
the a reduced version of the original one but likely that isn't the case. I'll
check.

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

Paolo Carlini  changed:

   What|Removed |Added

 CC||jason at gcc dot gnu.org,
   ||paolo.carlini at oracle dot com

--- Comment #3 from Paolo Carlini  ---
I spent only a few minutes on this and I'm not at all sure it's a bug. As I
read the standard - and our implementation - we are doing value-initializaation
here. In turn, for a scalar type like std::nullptr_t, that means
zero-initialization (11.6/6), which, in turn, means converting the integer
literal 0 to T, thus the warning. If there is a mistake in my reasoning above,
adding a special case to our implementation would be easy, I think.

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

Eric Gallager  changed:

   What|Removed |Added

   Keywords||diagnostic
 Status|UNCONFIRMED |NEW
   Last reconfirmed||2017-08-22
 CC||egallager at gcc dot gnu.org
 Ever confirmed|0   |1

--- Comment #2 from Eric Gallager  ---
Confirmed for both examples.

[Bug c++/70808] Spurious -Wzero-as-null-pointer-constant for nullptr_t

[jaak at ristioja dot ee]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70808

Jaak Ristioja  changed:

   What|Removed |Added

 CC||jaak at ristioja dot ee

--- Comment #1 from Jaak Ristioja  ---
A minimum example I've found for this is:

void f() { decltype(nullptr)(); }

With -std=c++11 the warning is emitted in versions 4.8.5, 4.9.3, 5.3.0, 5.4.0
and 6.2.0, but not in 4.7.4.