Hi,
for this small 5/6 regression (an ICE) Markus suggests in the audit
trail to protect the tree_to_shwi call with tree_fits_shwi_p. I tweaked
a bit his suggestion adopting a pattern already used, eg, in the parser,
and successfully tested it in trunk. I suppose it could make sense to
also fix the issue in the branch, if we can do that safely, and I also
propose below a variant for that (cxx_eval_array_reference is slightly
different in the branch). Ok?
Thanks,
Paolo.
////////////////////////////
/cp
2015-11-25 Markus Trippelsdorf <mar...@trippelsdorf.de>
Paolo Carlini <paolo.carl...@oracle.com>
PR c++/68087
* constexpr.c (cxx_eval_array_reference): Use tree_fits_shwi_p before
tree_to_shwi to avoid ICEs.
/testsuite
2015-11-25 Markus Trippelsdorf <mar...@trippelsdorf.de>
Paolo Carlini <paolo.carl...@oracle.com>
PR c++/68087
* g++.dg/cpp0x/constexpr-array13.C: New.
Index: cp/constexpr.c
===================================================================
--- cp/constexpr.c (revision 230865)
+++ cp/constexpr.c (working copy)
@@ -1799,8 +1799,8 @@ cxx_eval_array_reference (const constexpr_ctx *ctx
gcc_unreachable ();
}
- i = tree_to_shwi (index);
- if (i < 0)
+ if (!tree_fits_shwi_p (index)
+ || (i = tree_to_shwi (index)) < 0)
{
if (!ctx->quiet)
error ("negative array subscript");
Index: testsuite/g++.dg/cpp0x/constexpr-array13.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-array13.C (revision 0)
+++ testsuite/g++.dg/cpp0x/constexpr-array13.C (working copy)
@@ -0,0 +1,6 @@
+// PR c++/68087
+// { dg-do compile { target c++11 } }
+
+constexpr char c[] = "hello";
+constexpr const char *p = c;
+constexpr char ch = *(p-1); // { dg-error "negative array subscript" }
Index: cp/constexpr.c
===================================================================
--- cp/constexpr.c (revision 230866)
+++ cp/constexpr.c (working copy)
@@ -1751,7 +1751,7 @@ cxx_eval_array_reference (const constexpr_ctx *ctx
gcc_unreachable ();
}
- i = tree_to_shwi (index);
+ i = tree_fits_shwi_p (index) ? tree_to_shwi (index) : -1;
bool found = true;
if (TREE_CODE (ary) == CONSTRUCTOR && len
&& (TREE_CODE (CONSTRUCTOR_ELT (ary, len-1)->index) == RANGE_EXPR
Index: testsuite/g++.dg/cpp0x/constexpr-array13.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-array13.C (revision 0)
+++ testsuite/g++.dg/cpp0x/constexpr-array13.C (working copy)
@@ -0,0 +1,6 @@
+// PR c++/68087
+// { dg-do compile { target c++11 } }
+
+constexpr char c[] = "hello";
+constexpr const char *p = c;
+constexpr char ch = *(p-1); // { dg-error "negative array subscript" }
