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[RFC] PR C++/51225

Message ID 4ECD91CE.10408@oracle.com
State New
Headers show

Commit Message

Paolo Carlini Nov. 24, 2011, 12:37 a.m. UTC 
Hi again,
> Thus, what to do? Definitely adding CAST_EXPR to the switch works, but 
> I'm wondering if we could do something else... but doesn't seem easy 
> to me given the above. For example, I suppose changing 
> potential_constant_expression to return true for error_mark_node would 
> be catastrophic, even if error_mark_node is definitely constant ;)
Thus I decided to do the experiment: the below passes the testsuite, eh!

Interestingly the tweak to the testcase below *align* the error messages 
produced to those produced with -std=c++98, just a little more terse.  
Thus, is my idea really crazy after all? (of course, given the analysis 
in the previous message, c++/51225 is also fixed)

Thanks,
Paolo.

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Patch

Index: testsuite/g++.dg/cpp0x/regress/error-recovery1.C
===================================================================
--- testsuite/g++.dg/cpp0x/regress/error-recovery1.C	(revision 181678)
+++ testsuite/g++.dg/cpp0x/regress/error-recovery1.C	(working copy)
@@ -5,7 +5,7 @@  template < bool > void
 foo ()
 {
   const bool b =;		// { dg-error "" }
-  foo < b > ();			// { dg-error "constant expression" }
+  foo < b > ();
 };
 
 // { dg-error "no match" "" { target *-*-* } 8 }
Index: cp/semantics.c
===================================================================
--- cp/semantics.c	(revision 181678)
+++ cp/semantics.c	(working copy)
@@ -7923,9 +7923,7 @@  potential_constant_expression_1 (tree t, bool want
   if (cxx_dialect < cxx0x)
     return true;
 
-  if (t == error_mark_node)
-    return false;
-  if (t == NULL_TREE)
+  if (t == NULL_TREE || t == error_mark_node)
     return true;
   if (TREE_THIS_VOLATILE (t))
     {