[PATCH] c-family: Avoid ICEs on calls to internal functions [PR95963]

[Jakub Jelinek via Gcc-patches]

Hi!

The following testcase ICEs since recent Martin's -Wnonnull changes,
we see a CALL_EXPR and ICE because CALL_EXPR_FN is NULL, which is
valid for internal function calls.  Internal function calls don't have a
function type, and will never have format_arg attribute on them nor will
serve as the i18n routines -Wformat cares about.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2020-06-30  Jakub Jelinek  <ja...@redhat.com>

        PR c++/95963
        * c-common.c (check_function_arguments_recurse): Don't crash on
        calls to internal functions.

        * g++.dg/cpp1z/launder9.C: New test.

--- gcc/c-family/c-common.c.jj  2020-06-29 14:51:54.821086398 +0200
+++ gcc/c-family/c-common.c     2020-06-29 21:06:02.624773345 +0200
@@ -5815,7 +5815,7 @@ check_function_arguments_recurse (void (
       return;
     }
 
-  if (TREE_CODE (param) == CALL_EXPR)
+  if (TREE_CODE (param) == CALL_EXPR && CALL_EXPR_FN (param))
     {
       tree type = TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (param)));
       tree attrs;
--- gcc/testsuite/g++.dg/cpp1z/launder9.C.jj    2020-06-29 21:07:02.191932465 
+0200
+++ gcc/testsuite/g++.dg/cpp1z/launder9.C       2020-06-29 21:08:19.137846260 
+0200
@@ -0,0 +1,11 @@
+// PR c++/95963
+// { dg-do compile }
+// { dg-options "-Wnonnull" }
+
+struct A { virtual void foo (); };
+
+void
+bar (A *p)
+{
+  __builtin_launder (p)->foo ();
+}

        Jakub