[PATCH] handle MEM_REF with void* arguments (PR c++/95768)

[Martin Sebor via Gcc-patches]

The attached fix parallels the one for the equivalent C bug 95580
where the pretty printers don't correctly handle MEM_REF arguments
with type void* or other pointers to an incomplete type.

The incorrect handling was exposed by the recent change to
-Wuninitialized which includes such expressions in diagnostics.

Martin

PR c++/95768 - pretty-printer ICE on -Wuninitialized with allocated storage

gcc/cp/ChangeLog:

	PR c++/95768
	* error.c (dump_expr): Handle sizeless operand types such as void*.

gcc/testsuite/ChangeLog:

	PR c++/95768
	* g++.dg/pr95768.C: New test.

diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 0d6375e5e14..3a7254fdce1 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -2374,32 +2374,37 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
       break;
 
     case MEM_REF:
-      if (TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR
-	  && integer_zerop (TREE_OPERAND (t, 1)))
-	dump_expr (pp, TREE_OPERAND (TREE_OPERAND (t, 0), 0), flags);
-      else
-	{
-	  pp_cxx_star (pp);
-	  if (!integer_zerop (TREE_OPERAND (t, 1)))
-	    {
-	      pp_cxx_left_paren (pp);
-	      if (!integer_onep (TYPE_SIZE_UNIT
-				 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 0))))))
-		{
-		  pp_cxx_left_paren (pp);
-		  dump_type (pp, ptr_type_node, flags);
-		  pp_cxx_right_paren (pp);
-		}
-	    }
-	  dump_expr (pp, TREE_OPERAND (t, 0), flags);
-	  if (!integer_zerop (TREE_OPERAND (t, 1)))
-	    {
-	      pp_cxx_ws_string (pp, "+");
-	      dump_expr (pp, fold_convert (ssizetype, TREE_OPERAND (t, 1)),
-                         flags);
-	      pp_cxx_right_paren (pp);
-	    }
-	}
+      {
+	tree arg = TREE_OPERAND (t, 0);
+	tree offset = TREE_OPERAND (t, 1);
+
+	if (TREE_CODE (arg) == ADDR_EXPR
+	    && integer_zerop (offset))
+	  dump_expr (pp, TREE_OPERAND (arg, 0), flags);
+	else
+	  {
+	    pp_cxx_star (pp);
+	    if (!integer_zerop (offset))
+	      {
+		pp_cxx_left_paren (pp);
+		tree argtype = TREE_TYPE (arg);
+		if (tree size = TYPE_SIZE_UNIT (TREE_TYPE (argtype)))
+		  if (!integer_onep (size))
+		    {
+		      pp_cxx_left_paren (pp);
+		      dump_type (pp, ptr_type_node, flags);
+		      pp_cxx_right_paren (pp);
+		    }
+	      }
+	    dump_expr (pp, arg, flags);
+	    if (!integer_zerop (offset))
+	      {
+		pp_cxx_ws_string (pp, "+");
+		dump_expr (pp, fold_convert (ssizetype, offset), flags);
+		pp_cxx_right_paren (pp);
+	      }
+	  }
+      }
       break;
 
     case NEGATE_EXPR:
diff --git a/gcc/testsuite/g++.dg/pr95768.C b/gcc/testsuite/g++.dg/pr95768.C
new file mode 100644
index 00000000000..babfcb49bf8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr95768.C
@@ -0,0 +1,32 @@
+/* PR c++/95768 - pretty-printer ICE on -Wuninitialized with allocated storage
+   { dg-do compile }
+   { dg-options "-O2 -Wall" } */
+
+extern "C" void *malloc (__SIZE_TYPE__);
+
+struct f
+{
+  int i;
+  static int e (int);
+  void operator= (int) { e (i); }
+};
+
+struct m {
+  int i;
+  f length;
+};
+
+struct n {
+  m *o() { return (m *)this; }
+};
+
+struct p {
+  n *header;
+  p () {
+    header = (n *)malloc (0);
+    m b = *header->o();       // { dg-warning "-Wuninitialized" }
+    b.length = 0;
+  }
+};
+
+void detach2() { p(); }