[patch] Fix PR c++/22233, ICE on invalid number of template parameters

[Volker Reichelt]

Consider the following invalid testcase:

  template<int> struct A
  {
    A();
  };

  template<int N, char> A<N>::A() {}

  A<0> a;

After a suitable error message

  param1.C:6: error: got 2 template parameters for 'A<<anonymous> >::A()'
  param1.C:6: error:   but 1 required

we get an ICE when instantiating A:

  param1.C: In instantiation of 'A<0>':
  param1.C:8:   instantiated from here
  param1.C:6: internal compiler error: tree check: accessed elt 2 of tree_vec with 1 elts in tsubst, at cp/pt.c:7071

Btw, this happens with any member function, not just a constructor.

The patch fixes that by returning an error_mark_node from
push_template_decl_real when the non-matching template arguments
are encountered. This prevents that the invalid declaration is
considered at instantiation time.

Bootstrapped and regtested on i686-pc-linux-gnu.

Ok for mainline, 4.0 branch and 3.4 branch (since this is a regression)?

Regards,
Volker


2005-08-17  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>

	PR c++/22233
	* pt.c (push_template_decl_real): Return error_mark_node if the
	number of template parameters does not match previous definition.

===================================================================
--- gcc/gcc/cp/pt.c	12 Aug 2005 09:23:43 -0000	1.1022
+++ gcc/gcc/cp/pt.c	17 Aug 2005 11:11:45 -0000
@@ -3109,6 +3109,7 @@ push_template_decl_real (tree decl, int 
 		  error ("got %d template parameters for %q#T",
 			 TREE_VEC_LENGTH (a), current);
 		error ("  but %d required", TREE_VEC_LENGTH (t));
+		return error_mark_node;
 	      }
 
 	    /* Perhaps we should also check that the parms are used in the
===================================================================

2005-08-17  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>

	PR c++/22233
	* g++.dg/template/param1.C: New test.

===================================================================
--- gcc/gcc/testsuite/g++.dg/template/param1.C	2003-09-23 19:59:22 +0200
+++ gcc/gcc/testsuite/g++.dg/template/param1.C	2005-08-17 19:54:38 +0200
@@ -0,0 +1,12 @@
+// PR c++/22233
+// Origin: Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
+// { dg-do compile }
+
+template<int> struct A
+{
+  A();
+};
+
+template<int N, char> A<N>::A() {}  // { dg-error "got 2|but 1 required" }
+
+A<0> a;
===================================================================