C++ PATCH for c++/83186, ICE with static_cast and list-init

[Jason Merrill]

If we're going to try to do normal semantic checking of static_cast in
a template, we need to use build_non_dependent_expr like we do for
function calls.

Tested x86_64-pc-linux-gnu, applying to trunk.
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commit 4d7e6ada4e9f1c83d59b0e83d7e554ddae5cb3a8
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Jan 12 13:49:44 2018 -0500

            PR c++/83186 - ICE with static_cast of list-initialized temporary.
    
            * typeck.c (build_static_cast): Use build_non_dependent_expr.

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 669a2b45bfd..f0dc03de111 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -7204,6 +7204,8 @@ build_static_cast (tree type, tree oexpr, tsubst_flags_t complain)
       TREE_SIDE_EFFECTS (expr) = 1;
       return convert_from_reference (expr);
     }
+  else if (processing_template_decl)
+    expr = build_non_dependent_expr (expr);
 
   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
      Strip such NOP_EXPRs if VALUE is being used in non-lvalue context.  */
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-cast1.C b/gcc/testsuite/g++.dg/cpp0x/initlist-cast1.C
new file mode 100644
index 00000000000..5446d85f3aa
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-cast1.C
@@ -0,0 +1,12 @@
+// PR c++/83186
+// { dg-do compile { target c++11 } }
+
+struct a {
+  operator unsigned();
+};
+template <class> void b() { static_cast<unsigned>(a{}); }
+
+int main()
+{
+  b<int>();
+}