[PATCH] c-family: Fix up MEM_REF printing [PR95580]

[Jakub Jelinek via Gcc-patches]

Hi!

The C FE in the MEM_REF printing ICEs if the type of the first argument
(which due to useless pointer conversions can be an arbitrary type) is a
pointer to an incomplete type.  The code just wants to avoid printing a cast
if it is a pointer to single byte elements.

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

2020-06-08  Jakub Jelinek  <ja...@redhat.com>

        PR c/95580
        * c-pretty-print.c (c_pretty_printer::unary_expression): Handle the
        case when MEM_REF's first argument has type pointer to incomplete type.

        * gcc.dg/pr95580.c: New test.

--- gcc/c-family/c-pretty-print.c.jj    2020-06-08 10:21:38.651225945 +0200
+++ gcc/c-family/c-pretty-print.c       2020-06-08 19:11:27.623658024 +0200
@@ -1789,8 +1789,9 @@ c_pretty_printer::unary_expression (tree
          if (!integer_zerop (TREE_OPERAND (e, 1)))
            {
              pp_c_left_paren (this);
-             if (!integer_onep (TYPE_SIZE_UNIT
-                                (TREE_TYPE (TREE_TYPE (TREE_OPERAND (e, 0))))))
+             tree type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (e, 0)));
+             if (TYPE_SIZE_UNIT (type) == NULL_TREE
+                 || !integer_onep (TYPE_SIZE_UNIT (type)))
                pp_c_type_cast (this, ptr_type_node);
            }
          pp_c_cast_expression (this, TREE_OPERAND (e, 0));
--- gcc/testsuite/gcc.dg/pr95580.c.jj   2020-06-08 19:27:51.191128586 +0200
+++ gcc/testsuite/gcc.dg/pr95580.c      2020-06-08 19:27:26.487493595 +0200
@@ -0,0 +1,16 @@
+/* PR c/95580 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -W -fno-tree-dce" } */
+
+void bar (void);
+
+void
+foo (int x)
+{
+  if (x == 0)
+    {
+      void *p = __builtin_malloc (4);
+      ((char *)p)[1] ^= 1;     /* { dg-warning "may be used uninitialized" } */
+    }
+  bar ();
+}

        Jakub