re PR c++/63283 (constexpr function called by templated function is not treated as constexpr)

	PR c++/63283
	* constexpr.c (potential_constant_expression_1): Handle reference
	args in templates.

From-SVN: r219686

gcc/cp/ChangeLog

+2015-01-15  Jason Merrill  <jason@redhat.com>
+
+	PR c++/63283
+	* constexpr.c (potential_constant_expression_1): Handle reference
+	args in templates.
+
 2015-01-15  Thomas Schwinge  <thomas@codesourcery.com>
 	    James Norris  <jnorris@codesourcery.com>
 	    Cesar Philippidis  <cesar@codesourcery.com>

gcc/cp/constexpr.c

@@ -3881,7 +3881,11 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict,
         for (; i < nargs; ++i)
           {
             tree x = get_nth_callarg (t, i);
-	    if (!RECUR (x, rval))
+	    /* In a template, reference arguments haven't been converted to
+	       REFERENCE_TYPE and we might not even know if the parameter
+	       is a reference, so accept lvalue constants too.  */
+	    bool rv = processing_template_decl ? any : rval;
+	    if (!RECUR (x, rv))
 	      return false;
           }
         return true;

gcc/testsuite/g++.dg/cpp0x/constexpr-template8.C

+// PR c++/63283
+// { dg-do compile { target c++11 } }
+
+constexpr int array_length(int (&array)[3]) { return 3; }
+int a[] = { 1, 2, 3 };
+template <typename T> int f() {
+  struct { int e[array_length(a)]; } t;
+  return sizeof(t);
+}
+int main() { f<void>(); }

gcc/testsuite/g++.dg/cpp0x/static_assert10.C

@@ -4,5 +4,5 @@
 template<typename T> bool foo(T)
 {
   int i;
-  static_assert(foo(i), "Error"); // { dg-error "non-constant condition|not usable" }
+  static_assert(foo(i), "Error"); // { dg-error "non-constant condition|not usable|non-constexpr" }
 }