re PR c++/57869 ([C++11] Casting a object pointer to a function pointer should not warn about a forbidden conversion)

/c-family
2013-07-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57869
	* c.opt: Add Wconditionally-supported.

/cp
2013-07-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57869
	* typeck.c (build_reinterpret_cast_1): With -Wconditionally-supported
	warn about casting between pointer-to-function and pointer-to-object.

/gcc
2013-07-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57869
	* doc/invoke.texi: Document -Wconditionally-supported.

/testsuite
2013-07-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57869
	* g++.dg/cpp0x/reinterpret_cast1.C: New.
	* g++.dg/warn/Wconditionally-supported-1.C: Likewise.
	* g++.dg/conversion/dr195.C: Update.
	* g++.dg/expr/cast2.C: Likewise.

From-SVN: r200876

5 files changed, 49 insertions, 9 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 82502f5..520818f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2013-07-10  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/57869
+	* g++.dg/cpp0x/reinterpret_cast1.C: New.
+	* g++.dg/warn/Wconditionally-supported-1.C: Likewise.
+	* g++.dg/conversion/dr195.C: Update.
+	* g++.dg/expr/cast2.C: Likewise.
+
 2013-07-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR preprocessor/57757
diff --git a/gcc/testsuite/g++.dg/conversion/dr195.C b/gcc/testsuite/g++.dg/conversion/dr195.C
index 8502c15..cb26623 100644
--- a/gcc/testsuite/g++.dg/conversion/dr195.C
+++ b/gcc/testsuite/g++.dg/conversion/dr195.C
@@ -1,11 +1,12 @@
 // Copyright (C) 2004 Free Software Foundation, Inc.
 // Contributed by Nathan Sidwell 20 Oct 2004 <nathan@codesourcery.com>
 
-// DR 195 will allow conversions between function and object pointers
-// under some circumstances. It is in drafting, so we don't implement
-// it (yet).
+// DR 195 was about allowing conversions between function and object
+// pointers under some circumstances.  The issue got resolved for C++11,
+// which, in 5.2.10 p8 says that: "Converting a function pointer to an
+// object pointer type or vice versa is conditionally-supported."
 
-// This checks we warn when being pedantic.
+// This checks we don't warn anymore with -pedantic.
 
 typedef void (*PF)(void);
 typedef void *PV;
@@ -18,12 +19,12 @@ void foo ()
   PO po;
 
   /* the following two will almost definitly be ok with 195.  */
-  pf = reinterpret_cast <PF>(pv); // { dg-warning "casting between" "" }
-  pv = reinterpret_cast <PV>(pf); // { dg-warning "casting between" "" }
+  pf = reinterpret_cast <PF>(pv);
+  pv = reinterpret_cast <PV>(pf);
 
   /* the following two might or might not be ok with 195.  */
-  pf = reinterpret_cast <PF>(po); // { dg-warning "casting between" "" }
-  po = reinterpret_cast <PO>(pf); // { dg-warning "casting between" "" }
+  pf = reinterpret_cast <PF>(po);
+  po = reinterpret_cast <PO>(pf);
 
   /* These will never be ok, as they are implicit.  */
   pv = pf; // { dg-error "invalid conversion" "" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/reinterpret_cast1.C b/gcc/testsuite/g++.dg/cpp0x/reinterpret_cast1.C
new file mode 100644
index 0000000..7c0463e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/reinterpret_cast1.C
@@ -0,0 +1,6 @@
+// PR c++/57869
+// { dg-do compile { target c++11 } }
+
+void* po = 0;
+void (*pf)() = reinterpret_cast<decltype(pf)>(po);
+static_assert(sizeof(po) >= sizeof(pf), "Conversion not supported");
diff --git a/gcc/testsuite/g++.dg/expr/cast2.C b/gcc/testsuite/g++.dg/expr/cast2.C
index 1ccda2b..f3c18d5 100644
--- a/gcc/testsuite/g++.dg/expr/cast2.C
+++ b/gcc/testsuite/g++.dg/expr/cast2.C
@@ -1,5 +1,5 @@
 void (*p)();
 
 void f() {
-  (void *)p; // { dg-warning "forbids cast" }
+  (void *)p;
 }
diff --git a/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C b/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C
new file mode 100644
index 0000000..8cc5966
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C
@@ -0,0 +1,25 @@
+// { dg-options "-Wconditionally-supported" }
+
+// DR 195 was about allowing conversions between function and object
+// pointers under some circumstances.  The issue got resolved for C++11,
+// which, in 5.2.10 p8 says that: "Converting a function pointer to an 
+// object pointer type or vice versa is conditionally-supported."
+
+// This checks we warn with -Wconditionally-supported.
+
+typedef void (*PF)(void);
+typedef void *PV;
+typedef int *PO;
+
+void foo ()
+{
+  PF pf;
+  PV pv;
+  PO po;
+
+  pf = reinterpret_cast <PF>(pv); // { dg-warning "conditionally-supported" }
+  pv = reinterpret_cast <PV>(pf); // { dg-warning "conditionally-supported" }
+
+  pf = reinterpret_cast <PF>(po); // { dg-warning "conditionally-supported" }
+  po = reinterpret_cast <PO>(pf); // { dg-warning "conditionally-supported" }
+}