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[C++ PATCH] Don't pass VLA bounds with arbitrary C++ specific trees to build_array_type (PR c++/28879)


Even when TYPE_MAX_VALUE (index_type) is not value_dependent_expression_p,
it can still contain various C++ FE tree nodes, which the middle-end won't
be happy about.  Or do I need both v_d_e_p check and the VLA check?
Regtested on x86_64-linux.

This fixes just part of the PR though, the other testcase ICEs in
value_dependent_expression_p, because with VLAs inside of template
function/method bodies size in compute_array_index_type
can be almost arbitrary expression (including e.g. statement expressions,
etc.) and value_dependent_expression_p makes some assumptions on what it
can be fed with.  That was introduced by Nathan in PR9043.
I wonder if we could get away without calling it altogether, run
integral_constant_value always and whenever that doesn't yield an
INTEGER_CST, use build_min on the original size rather than the folded.
Alternatively we need value_dependent_expression_p to handle really
arbitrary expressions (or copy/adjust it into a new function which will
do that).

2007-11-19  Jakub Jelinek  <>

	PR c++/28879
	* tree.c (build_cplus_array_type_1): Don't pass any VLA types
	when processing_template_decl to build_array_type.

	* g++.dg/template/vla2.C: New test.

--- gcc/cp/tree.c.jj	2007-11-10 01:14:58.000000000 +0100
+++ gcc/cp/tree.c	2007-11-19 13:28:16.000000000 +0100
@@ -531,7 +531,8 @@ build_cplus_array_type_1 (tree elt_type,
   if (dependent_type_p (elt_type)
       || (index_type
-	  && value_dependent_expression_p (TYPE_MAX_VALUE (index_type))))
+	  && processing_template_decl
+	  && !TREE_CONSTANT (TYPE_MAX_VALUE (index_type))))
       void **e;
       cplus_array_info cai;
@@ -570,7 +571,7 @@ build_cplus_array_type_1 (tree elt_type,
 		= build_cplus_array_type 
 		   (TYPE_CANONICAL (elt_type),
-		    index_type? TYPE_CANONICAL (index_type) : index_type);
+		    index_type ? TYPE_CANONICAL (index_type) : index_type);
 	    TYPE_CANONICAL (t) = t;
--- gcc/testsuite/g++.dg/template/vla2.C.jj	2007-11-19 13:52:29.000000000 +0100
+++ gcc/testsuite/g++.dg/template/vla2.C	2007-11-19 13:52:15.000000000 +0100
@@ -0,0 +1,20 @@
+// PR c++/28879
+// { dg-do compile }
+// { dg-options "" }
+struct A
+  static int i;
+  int j;
+template<int> void foo ()
+  int x[A::i];
+//int y[A().j];
+void bar ()
+  foo<6> ();


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