Patchwork C++ PATCH for c++/52988 (omitted calls with nullptr)

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Submitter Jason Merrill
Date June 25, 2012, 5:41 p.m.
Message ID <4FE8A2B2.9080802@redhat.com>
Download mbox | patch
Permalink /patch/167183/
State New
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Comments

Jason Merrill - June 25, 2012, 5:41 p.m.
We were assuming that any expression of nullptr_t was equivalent to 
nullptr, but that isn't valid if the expression has side-effects...

Tested x86_64-pc-linux-gnu, applying to 4.6, 4.7, trunk.

Patch

commit c716e8680864db1312338691de7d2618efec1c3f
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jun 25 13:06:15 2012 -0400

    	PR c++/52988
    	* typeck.c (decay_conversion): Don't discard side-effects from
    	expressions of nullptr_t.

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 945266b..971f386 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -1843,7 +1843,7 @@  decay_conversion (tree exp, tsubst_flags_t complain)
   if (error_operand_p (exp))
     return error_mark_node;
 
-  if (NULLPTR_TYPE_P (type))
+  if (NULLPTR_TYPE_P (type) && !TREE_SIDE_EFFECTS (exp))
     return nullptr_node;
 
   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
diff --git a/gcc/testsuite/g++.dg/cpp0x/nullptr28.C b/gcc/testsuite/g++.dg/cpp0x/nullptr28.C
new file mode 100644
index 0000000..05fbe57
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nullptr28.C
@@ -0,0 +1,16 @@ 
+// { dg-do run { target c++11 } }
+
+typedef decltype(nullptr) nullptr_t;
+
+int i;
+nullptr_t n;
+const nullptr_t& f() { ++i; return n; }
+
+nullptr_t g() { return f(); }
+
+int main()
+{
+  g();
+  if (i != 1)
+    __builtin_abort ();
+}