[C++ PATCH] Fix diagnostic printing of COMPONENT_REF with ARROW_EXPR first operand (PR c++/79304)

[Jakub Jelinek]

Hi!

For dependent expression followed by -> and identifier or ~ identifier,
the parser creates COMPONENT_REF with ARROW_EXPR as its first argument.
When printing that, we actually print expr->.identifier , which is not
what the user typed.  The following patch omits the undesirable dot in
that case, we know that dump_expr on the ARROW_EXPR already printed ->

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2017-01-31  Jakub Jelinek  <ja...@redhat.com>

        PR c++/79304
        * error.c (dump_expr) <case COMPONENT_REF>: Don't print .
        after ARROW_EXPR.

        * g++.dg/diagnostic/pr79304.C: New test.

--- gcc/cp/error.c.jj   2017-01-21 02:26:06.000000000 +0100
+++ gcc/cp/error.c      2017-01-31 17:03:17.737123973 +0100
@@ -2247,7 +2247,8 @@ dump_expr (cxx_pretty_printer *pp, tree
        else
          {
            dump_expr (pp, ob, flags | TFF_EXPR_IN_PARENS);
-           pp_cxx_dot (pp);
+           if (TREE_CODE (ob) != ARROW_EXPR)
+             pp_cxx_dot (pp);
          }
        dump_expr (pp, TREE_OPERAND (t, 1), flags & ~TFF_EXPR_IN_PARENS);
       }
--- gcc/testsuite/g++.dg/diagnostic/pr79304.C.jj        2017-01-31 
17:08:17.347318113 +0100
+++ gcc/testsuite/g++.dg/diagnostic/pr79304.C   2017-01-31 17:08:01.000000000 
+0100
@@ -0,0 +1,20 @@
+// PR c++/79304
+// { dg-do compile }
+
+struct C { };
+
+template<class T>
+struct X
+{
+  C* c;
+
+  void f() {
+    this->c.s();       // { dg-error "->c" }
+  }
+};
+
+int main()
+{
+  X<int> x;
+  x.f();
+}

        Jakub