Re: [C++ Patch] PR 79380

[Jason Merrill]

OK.

On Fri, Feb 17, 2017 at 8:32 AM, Paolo Carlini  wrote:
> ... sorry, what I meant to propose uses
> INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P in the check, per the below. Both
> versions pass testing anyway, but the below seems more correct to me.
>
> Thanks again,
> Paolo.
>
> 

Re: [C++ Patch] PR 79380

[Paolo Carlini]

... sorry, what I meant to propose uses 
INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P in the check, per the below. 
Both versions pass testing anyway, but the below seems more correct to me.


Thanks again,
Paolo.


Index: cp/typeck.c
===
--- cp/typeck.c (revision 245503)
+++ cp/typeck.c (working copy)
@@ -1795,6 +1795,12 @@ cxx_alignas_expr (tree e)
 
  the assignment-expression shall be an integral constant
 expression.  */
+
+  if (!INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (e)))
+{
+  error ("% argument has non-integral type %qT", TREE_TYPE (e));
+  return error_mark_node;
+}
   
   return cxx_constant_value (e);
 }
Index: testsuite/g++.dg/cpp0x/alignas8.C
===
--- testsuite/g++.dg/cpp0x/alignas8.C   (revision 0)
+++ testsuite/g++.dg/cpp0x/alignas8.C   (working copy)
@@ -0,0 +1,7 @@
+// PR c++/79380
+// { dg-do compile { target c++11 } }
+
+template < typename > constexpr int f () {  return 8;  }
+
+// should have been: struct alignas (f()) S {};
+struct alignas (f) S {};  // { dg-error "17:'alignas' argument has 
non-integral type" }

[C++ Patch] PR 79380

[Paolo Carlini]

Hi,

this ICE on invalid seems quite similar to c++/69637 which I fixed 
recently: we again end up with an unhandled OVERLOAD in the main 
cxx_eval_constant_expression switch and in this case we don't diagnose 
at all the invalid input. Thus, I propose to add a check to 
cxx_alignas_expr completely similar to what we have in grokbitfield on 
the width. Tested x86_64-linux.


Thanks, Paolo.

PS: I think we are moving away from pretty printing (%qE) expressions, 
thus I dind't try in the patchlet to print the argument, only its 
(wrong) type.


//

/cp
2017-02-17  Paolo Carlini  

PR c++/79380
* typeck.c (cxx_alignas_expr): Reject a non-integral alignas
argument.

/testsuite
2017-02-17  Paolo Carlini  

PR c++/79380
* g++.dg/cpp0x/alignas8.C: New.
Index: cp/typeck.c
===
--- cp/typeck.c (revision 245503)
+++ cp/typeck.c (working copy)
@@ -1795,6 +1795,12 @@ cxx_alignas_expr (tree e)
 
  the assignment-expression shall be an integral constant
 expression.  */
+
+  if (!INTEGRAL_OR_ENUMERATION_TYPE_P (TREE_TYPE (e)))
+{
+  error ("% argument has non-integral type %qT", TREE_TYPE (e));
+  return error_mark_node;
+}
   
   return cxx_constant_value (e);
 }
Index: testsuite/g++.dg/cpp0x/alignas8.C
===
--- testsuite/g++.dg/cpp0x/alignas8.C   (revision 0)
+++ testsuite/g++.dg/cpp0x/alignas8.C   (working copy)
@@ -0,0 +1,7 @@
+// PR c++/79380
+// { dg-do compile { target c++11 } }
+
+template < typename > constexpr int f () {  return 8;  }
+
+// should have been: struct alignas (f()) S {};
+struct alignas (f) S {};  // { dg-error "17:'alignas' argument has 
non-integral type" }