Re: [C++ Patch] PR 42056

[Paolo Carlini <paolo.carlini@oracle.com>]

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Hi,
> On 05/26/2011 02:30 PM, Paolo Carlini wrote:
>> We want to do that only when processing a template, because otherwise we
>> get a duplicate diagnostic, see, eg, auto9.C
> Hmm, where's the error coming from in the non-template case?  From 
> cp_build_c_cast?  In that case always giving the error in 
> build_functional_cast and then returning error_mark_node should avoid 
> duplication.
I should have told you. The error is produced via 
complete_type_or_maybe_complain called from line 1650 of 
build_functional_cast itself, by cxx_incomplete_type_diagnostic.
>> error_mark_node unconditionally, means a better diagnostic, without
>> redundant "array bound is not an integer constant before...".
> I'd rather deal with that by suppressing that error if we already have 
> error_mark_node.
complete_type_or_maybe_complain, when type is an error_mark_node 
understands that an error has been produced already and simply returns 
NULL_TREE. Thus, something like the below works. Is it closer to what 
you had in mind?

Paolo.

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/cp
2011-05-27  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/42056
	* typeck2.c (build_functional_cast): Complain early for invalid uses
	of 'auto' and set type to error_mark_node.

/testsuite
2011-05-27  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/42056
	* testsuite/g++.dg/cpp0x/auto25.C: New.
	* testsuite/g++.dg/cpp0x/auto26.C: Likewise.

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Index: testsuite/g++.dg/cpp0x/auto25.C
===================================================================
--- testsuite/g++.dg/cpp0x/auto25.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/auto25.C	(revision 0)
@@ -0,0 +1,7 @@
+// PR c++/42056
+// { dg-options -std=c++0x }
+
+template<int> struct A
+{
+  int a[auto(1)]; // { dg-error "invalid use of" }
+};
Index: testsuite/g++.dg/cpp0x/auto26.C
===================================================================
--- testsuite/g++.dg/cpp0x/auto26.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/auto26.C	(revision 0)
@@ -0,0 +1,7 @@
+// PR c++/42056
+// { dg-options -std=c++0x }
+
+template<int> void foo()
+{
+  int a[auto(1)]; // { dg-error "invalid use of" }
+}
Index: cp/typeck2.c
===================================================================
--- cp/typeck2.c	(revision 174321)
+++ cp/typeck2.c	(working copy)
@@ -1599,6 +1599,13 @@ build_functional_cast (tree exp, tree parms, tsubs
       return error_mark_node;
     }
 
+  if (type_uses_auto (type))
+    {
+      if (complain & tf_error)
+	error ("invalid use of %<auto%>");
+      type = error_mark_node;
+    }
+
   if (processing_template_decl)
     {
       tree t;