78 lines
2.2 KiB
Diff
78 lines
2.2 KiB
Diff
commit 6d134ca4b963706f31251f061fc180e517b32546
|
|
Author: Martin Sebor <msebor@redhat.com>
|
|
Date: Tue Feb 23 14:09:00 2021 -0700
|
|
|
|
PR c++/99074 - crash in dynamic_cast<>() on null pointer
|
|
|
|
libstdc++-v3/ChangeLog:
|
|
|
|
PR c++/99074
|
|
* libsupc++/dyncast.cc (__dynamic_cast): Return null when
|
|
first argument is null.
|
|
|
|
gcc/testsuite/ChangeLog:
|
|
|
|
PR c++/99074
|
|
* g++.dg/warn/Wnonnull11.C: New test.
|
|
|
|
diff --git a/gcc/testsuite/g++.dg/warn/Wnonnull11.C b/gcc/testsuite/g++.dg/warn/Wnonnull11.C
|
|
new file mode 100644
|
|
index 00000000000..5f1b69d9a41
|
|
--- /dev/null
|
|
+++ b/gcc/testsuite/g++.dg/warn/Wnonnull11.C
|
|
@@ -0,0 +1,40 @@
|
|
+/* PR c++/99074 - gcc 8 and above is crashing with dynamic_cast<>() on null
|
|
+ pointer with optimization level -O1 and above
|
|
+ { dg-do run }
|
|
+ { dg-options "-O1 -Wall" } */
|
|
+
|
|
+class Base
|
|
+{
|
|
+public:
|
|
+ virtual ~Base() {}
|
|
+ virtual void op() = 0;
|
|
+};
|
|
+
|
|
+class Object: public virtual Base { };
|
|
+
|
|
+class AbstractBase: public virtual Base
|
|
+{
|
|
+public:
|
|
+ Object* _to_object ()
|
|
+ {
|
|
+ return dynamic_cast<Object*>(this); // { dg-warning "\\\[-Wnonnull" "" { xfail *-*-* } }
|
|
+ }
|
|
+};
|
|
+
|
|
+class MyAbstractClass: public virtual AbstractBase
|
|
+{
|
|
+public:
|
|
+ static MyAbstractClass* _nil () { return 0; }
|
|
+};
|
|
+
|
|
+
|
|
+int main ()
|
|
+{
|
|
+ MyAbstractClass *my_abs_type = MyAbstractClass::_nil ();
|
|
+ AbstractBase *abs_base = my_abs_type;
|
|
+ Object *obj = abs_base->_to_object ();
|
|
+
|
|
+ __builtin_printf ("object is: %p\n", obj);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
diff --git a/libstdc++-v3/libsupc++/dyncast.cc b/libstdc++-v3/libsupc++/dyncast.cc
|
|
index b7d98495ad3..f8f707ee4d4 100644
|
|
--- a/libstdc++-v3/libsupc++/dyncast.cc
|
|
+++ b/libstdc++-v3/libsupc++/dyncast.cc
|
|
@@ -47,6 +47,9 @@ __dynamic_cast (const void *src_ptr, // object started from
|
|
const __class_type_info *dst_type, // desired target type
|
|
ptrdiff_t src2dst) // how src and dst are related
|
|
{
|
|
+ if (!src_ptr)
|
|
+ /* Handle precondition violations gracefully. */
|
|
+ return NULL;
|
|
const void *vtable = *static_cast <const void *const *> (src_ptr);
|
|
const vtable_prefix *prefix =
|
|
adjust_pointer <vtable_prefix> (vtable,
|