C++ PATCH for c++/79606, ICE with this->base_member in NSDMI

[Jason Merrill]

build_base_path knows that it should limit what it tries to do within
a template, but that handling wasn't being used within an NSDMI, only
within a template function.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit 7a11cba1268aa91df1bc253c43deb2dcbfd5b091
Author: Jason Merrill <ja...@redhat.com>
Date:   Sun Feb 19 15:55:10 2017 -0800

            PR c++/79606 - ICE with this->base_member in NSDMI
    
            * class.c (build_base_path): Check processing_template_decl.

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 1442b55..9e4b4c4 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -375,6 +375,7 @@ build_base_path (enum tree_code code,
      set up properly yet, and the value doesn't matter there either; we're
      just interested in the result of overload resolution.  */
   if (cp_unevaluated_operand != 0
+      || processing_template_decl
       || in_template_function ())
     {
       expr = build_nop (ptr_target_type, expr);
diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template16.C 
b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template16.C
new file mode 100644
index 0000000..58dec7b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template16.C
@@ -0,0 +1,14 @@
+// PR c++/79606
+// { dg-do compile { target c++11 } }
+
+struct A
+{
+  int i = 0;
+};
+
+template<int> struct B : A
+{
+  int j = this->i;
+};
+
+B<0> b;