re PR c++/52026 (Constexpr Variable Appears Uninitialized in Lambda)

PR c++/52026
	* semantics.c (finish_id_expression): In a template, return
	the identifier for a constant variable.

From-SVN: r196081

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2013-02-15  Jason Merrill  <jason@redhat.com>
+
+	PR c++/52026
+	* semantics.c (finish_id_expression): In a template, return
+	the identifier for a constant variable.
+
 2013-02-14  Jason Merrill  <jason@redhat.com>
 
 	PR c++/54922

gcc/cp/semantics.c

@@ -3015,7 +3015,14 @@ finish_id_expression (tree id_expression,
 
 	     FIXME update for final resolution of core issue 696.  */
 	  if (decl_constant_var_p (decl))
-	    return integral_constant_value (decl);
+	    {
+	      if (processing_template_decl)
+		/* In a template, the constant value may not be in a usable
+		   form, so look it up again at instantiation time.  */
+		return id_expression;
+	      else
+		return integral_constant_value (decl);
+	    }
 
 	  /* If we are in a lambda function, we can move out until we hit
 	     1. the context,

gcc/testsuite/g++.dg/cpp0x/lambda/lambda-const2.C

@@ -0,0 +1,15 @@
+// PR c++/52026
+// { dg-options "-std=c++11 -O" }
+// { dg-do run }
+
+template<bool B>
+int func() {
+  const int constVal1 = B ? 100 : -100;
+  const int constVal = constVal1;
+  return [] { return constVal; }();
+}
+
+int main() {
+  if (func<true>() != 100)
+    __builtin_abort ();
+}