Patchwork [C++,/,RFC] PR 51422

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Submitter Paolo Carlini
Date Sept. 27, 2012, 11:08 a.m.
Message ID <506433B1.1010206@oracle.com>
Download mbox | patch
Permalink /patch/187325/
State New
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Comments

Paolo Carlini - Sept. 27, 2012, 11:08 a.m.
Hi,

almost forgot that a few weeks ago I spent some time on this PR...

The issue is simple: in these repeated error conditions we ICE on the 
gcc_assert in is_normal_capture_proxy: decl is a VAR_DECL with an 
error_mark_node as TREE_TYPE.

Then checking error_operand_p (decl) in is_capture_proxy solves the 
problem but now the question is: do we have reasons to believe that such 
VAR_DECLs should never ever reach is_normal_capture_proxy? Otherwise 
robustifying a predicate like this seems a good idea to me. Patch passes 
testing on x86_64-linux of course.

Thanks!
Paolo.

///////////////////////////
Jason Merrill - Oct. 6, 2012, 1:52 p.m.
On 09/27/2012 07:08 AM, Paolo Carlini wrote:
> Then checking error_operand_p (decl) in is_capture_proxy solves the
> problem but now the question is: do we have reasons to believe that such
> VAR_DECLs should never ever reach is_normal_capture_proxy?

That depends on our error recovery strategy for an invalid capture.  It 
seems that we currently build a VAR_DECL that has an error_mark_node 
DECL_VALUE_EXPR; if we're going to do that, we need to deal with it.  I 
guess we should return true in that case, if it doesn't cause more 
problems later on.

Jason

Patch

Index: cp/semantics.c
===================================================================
--- cp/semantics.c	(revision 190666)
+++ cp/semantics.c	(working copy)
@@ -8929,6 +8929,9 @@  capture_decltype (tree decl)
 bool
 is_capture_proxy (tree decl)
 {
+  if (error_operand_p (decl))
+    return false;
+
   return (TREE_CODE (decl) == VAR_DECL
 	  && DECL_HAS_VALUE_EXPR_P (decl)
 	  && !DECL_ANON_UNION_VAR_P (decl)
Index: testsuite/g++.dg/cpp0x/lambda/lambda-ice8.C
===================================================================
--- testsuite/g++.dg/cpp0x/lambda/lambda-ice8.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/lambda/lambda-ice8.C	(revision 0)
@@ -0,0 +1,10 @@ 
+// PR c++/51422
+// { dg-do compile { target c++11 } }
+
+template<typename> struct A {};
+
+void foo()
+{
+  [i] { A<decltype(i)>(); };     // { dg-error "not declared|invalid" }
+  [i] { A<decltype(i)>(); };     // { dg-error "invalid" }
+}