[C++ PATCH] Avoid ICE trying to add a bogus fixit hint (PR c++/88554)

[Jakub Jelinek]

Hi!

As found by Jonathan, we shouldn't be trying to emit return *this; fixit
hint in non-methods where this is not available (and ICEing because
current_class_ref is NULL there).
I've just added a testcase for Jon's patch from the PR and merged two nested
ifs into one.

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

2019-01-04  Jonathan Wakely  <jwak...@redhat.com>
            Jakub Jelinek  <ja...@redhat.com>

        PR c++/88554
        * decl.c (finish_function): For -Wreturn-type don't add a return *this;
        fixit hint if current_class_ref is NULL.  Use a single if instead of
        two nested ones.

        * g++.dg/warn/Wreturn-type-11.C: New test.

--- gcc/cp/decl.c.jj    2019-01-03 11:11:11.568612960 +0100
+++ gcc/cp/decl.c       2019-01-04 20:33:39.258819779 +0100
@@ -16094,11 +16094,12 @@ finish_function (bool inline_p)
        {
          tree valtype = TREE_TYPE (DECL_RESULT (fndecl));
          if (TREE_CODE (valtype) == REFERENCE_TYPE
+             && current_class_ref
              && same_type_ignoring_top_level_qualifiers_p
-                 (TREE_TYPE (valtype), TREE_TYPE (current_class_ref)))
-           if (global_dc->option_enabled (OPT_Wreturn_type,
-                                          global_dc->option_state))
-             add_return_star_this_fixit (&richloc, fndecl);
+                 (TREE_TYPE (valtype), TREE_TYPE (current_class_ref))
+             && global_dc->option_enabled (OPT_Wreturn_type,
+                                           global_dc->option_state))
+           add_return_star_this_fixit (&richloc, fndecl);
        }
       warning_at (&richloc, OPT_Wreturn_type,
                  "no return statement in function returning non-void");
--- gcc/testsuite/g++.dg/warn/Wreturn-type-11.C.jj      2019-01-04 
20:34:18.062185207 +0100
+++ gcc/testsuite/g++.dg/warn/Wreturn-type-11.C 2019-01-04 20:35:36.048909843 
+0100
@@ -0,0 +1,11 @@
+// PR c++/88554
+// { dg-do compile }
+// { dg-options "-Wreturn-type" }
+
+struct X {
+  friend X & operator+= (X &, int) { } // { dg-warning "no return statement in 
function returning non-void" }
+                                       // { dg-bogus "return \\*this;" "" { 
target *-*-* } .-1 }
+};
+struct Y {};
+Y & operator += (Y &, Y &) { }         // { dg-warning "no return statement in 
function returning non-void" }
+                                       // { dg-bogus "return \\*this;" "" { 
target *-*-* } .-1 }

        Jakub