PR c++/90473 - wrong code with nullptr in default argument.

* call.c (null_ptr_cst_p): Update quote from the standard.
	* decl.c (check_default_argument): Don't return nullptr when the arg
	has side-effects.

	* g++.dg/cpp0x/nullptr42.C: New test.

From-SVN: r274382
This commit is contained in:
Marek Polacek 2019-08-13 15:05:48 +00:00 committed by Marek Polacek
parent 82614ffbfd
commit cb0a83f343
5 changed files with 35 additions and 4 deletions

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@ -1,3 +1,10 @@
2019-08-13 Marek Polacek <polacek@redhat.com>
PR c++/90473 - wrong code with nullptr in default argument.
* call.c (null_ptr_cst_p): Update quote from the standard.
* decl.c (check_default_argument): Don't return nullptr when the arg
has side-effects.
2019-08-13 Marek Polacek <polacek@redhat.com>
* cp-tree.h (DECL_MUTABLE_P): Use FIELD_DECL_CHECK.

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@ -529,9 +529,8 @@ null_ptr_cst_p (tree t)
/* [conv.ptr]
A null pointer constant is an integral constant expression
(_expr.const_) rvalue of integer type that evaluates to zero or
an rvalue of type std::nullptr_t. */
A null pointer constant is an integer literal ([lex.icon]) with value
zero or a prvalue of type std::nullptr_t. */
if (NULLPTR_TYPE_P (type))
return true;

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@ -13177,7 +13177,9 @@ check_default_argument (tree decl, tree arg, tsubst_flags_t complain)
/* Avoid redundant -Wzero-as-null-pointer-constant warnings at
the call sites. */
if (TYPE_PTR_OR_PTRMEM_P (decl_type)
&& null_ptr_cst_p (arg))
&& null_ptr_cst_p (arg)
/* Don't lose side-effects as in PR90473. */
&& !TREE_SIDE_EFFECTS (arg))
return nullptr_node;
/* [dcl.fct.default]

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@ -1,3 +1,8 @@
2019-08-13 Marek Polacek <polacek@redhat.com>
PR c++/90473 - wrong code with nullptr in default argument.
* g++.dg/cpp0x/nullptr42.C: New test.
2019-08-13 Olivier Hainque <hainque@adacore.com>
* gnat.dg/casesi.ad[bs], test_casesi.adb: New test.

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@ -0,0 +1,18 @@
// PR c++/90473 - wrong code with nullptr in default argument.
// { dg-do run { target c++11 } }
int g;
void f() { g++; }
void fn1 (void* p = (f(), nullptr)) { }
void fn2 (int p = (f(), 0)) { }
int main()
{
fn1 ();
if (g != 1)
__builtin_abort ();
fn2 ();
if (g != 2)
__builtin_abort ();
}