[C++ Patch] Fix 66243, silent cast of scoped enum

[C++ Patch] Fix 66243, silent cast of scoped enum

[Nathan Sidwell]

[-- Attachment #1: Type: text/plain, Size: 205 bytes --]

This is a pretty obvious patch.  We were permitting a scoped enum initializer of 
an another enum to silently decay to int.  That's not right, only unscoped enums 
have that privilege.

committed.

nathan

[-- Attachment #2: 66243.patch --]
[-- Type: text/x-patch, Size: 1139 bytes --]

2015-05-24  Nathan Sidwell  <nathan@acm.org>

	cp/
	PR c++/66243
	* decl.c (build_enumerator): Don't silently convert scoped enums.

	testsuite/
	PR c++/66243
	* g++.dg/cpp0x/pr66243.C: New.

Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 223613)
+++ cp/decl.c	(working copy)
@@ -13097,7 +13097,8 @@ build_enumerator (tree name, tree value,
 	      if (tmp_value)
 		value = tmp_value;
 	    }
-	  else if (! INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (value)))
+	  else if (! INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P
+		   (TREE_TYPE (value)))
 	    value = perform_implicit_conversion_flags
 	      (ENUM_UNDERLYING_TYPE (enumtype), value, tf_warning_or_error,
 	       LOOKUP_IMPLICIT | LOOKUP_NO_NARROWING);
Index: testsuite/g++.dg/cpp0x/pr66243.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr66243.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/pr66243.C	(working copy)
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++11 } }
+
+enum class A
+{
+  X
+};
+
+enum class B
+{
+  X = A::X // { dg-error "could not convert" }
+};
+

Re: [C++ Patch] Fix 66243, silent cast of scoped enum

[Jason Merrill]

On 05/24/2015 07:20 PM, Nathan Sidwell wrote:
> -	  else if (! INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (value)))
> +	  else if (! INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P
> +		   (TREE_TYPE (value)))
>  	    value = perform_implicit_conversion_flags
>  	      (ENUM_UNDERLYING_TYPE (enumtype), value, tf_warning_or_error,
>  	       LOOKUP_IMPLICIT | LOOKUP_NO_NARROWING);

The change is fine, but I wonder why perform_implicit_conversion_flags 
was succeeding?  I would think it should fail.

Jason

Re: [C++ Patch] Fix 66243, silent cast of scoped enum

[Nathan Sidwell]

On 05/25/15 15:43, Jason Merrill wrote:
> On 05/24/2015 07:20 PM, Nathan Sidwell wrote:
>> -      else if (! INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (value)))
>> +      else if (! INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P
>> +           (TREE_TYPE (value)))
>>          value = perform_implicit_conversion_flags
>>            (ENUM_UNDERLYING_TYPE (enumtype), value, tf_warning_or_error,
>>             LOOKUP_IMPLICIT | LOOKUP_NO_NARROWING);
>
> The change is fine, but I wonder why perform_implicit_conversion_flags was
> succeeding?  I would think it should fail.

It wasn't being executed.  The if condition is if *NOT* integral-or-enum.   The 
patch changes the check such that p_i_c_f is now executed for scoped enums  -- 
and emits an appropriate error.

nathan

Re: [C++ Patch] Fix 66243, silent cast of scoped enum

[Jason Merrill]

On 05/25/2015 04:14 PM, Nathan Sidwell wrote:
> On 05/25/15 15:43, Jason Merrill wrote:
>> On 05/24/2015 07:20 PM, Nathan Sidwell wrote:
>>> -      else if (! INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (value)))
>>> +      else if (! INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P
>>> +           (TREE_TYPE (value)))
>>>          value = perform_implicit_conversion_flags
>>>            (ENUM_UNDERLYING_TYPE (enumtype), value, tf_warning_or_error,
>>>             LOOKUP_IMPLICIT | LOOKUP_NO_NARROWING);
>>
>> The change is fine, but I wonder why perform_implicit_conversion_flags
>> was
>> succeeding?  I would think it should fail.
>
> It wasn't being executed.  The if condition is if *NOT*
> integral-or-enum.   The patch changes the check such that p_i_c_f is now
> executed for scoped enums  -- and emits an appropriate error.

Ah, of course, thanks.

Jason