Tests for various kinds of spurious uninit variable warning.

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Tests for various kinds of spurious uninit variable warning.
All are derived from cpplib; see comments in the files.

From-SVN: r25710

gcc/testsuite/gcc.dg/uninit-2.c

+/* Spurious uninitialized variable warnings, case 2.
+   Taken from cpphash.c (macroexpand) */
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+struct definition
+{
+  int nargs;
+  int rest_args;
+};
+
+struct cpp_reader;
+
+enum cpp_token
+{
+  CPP_EOF, CPP_POP, CPP_COMMA, CPP_RPAREN
+};
+
+extern enum cpp_token macarg (struct cpp_reader *, int);
+
+void
+macroexpand (struct cpp_reader *pfile, struct definition *defn)
+{
+  int nargs = defn->nargs;
+
+  if (nargs >= 0)
+    {
+      enum cpp_token token;  /* { dg-bogus "token" "uninitialized variable warning" { xfail *-*-* } } */
+      int i, rest_args;
+      i = 0;
+      rest_args = 0;
+      do
+	{
+	  if (rest_args)
+	    continue;
+	  if (i < nargs || (nargs == 0 && i == 0))
+	    {
+	      /* if we are working on last arg which absorbs rest of args... */
+	      if (i == nargs - 1 && defn->rest_args)
+		rest_args = 1;
+	      token = macarg (pfile, rest_args);
+	    }
+	  else
+	    token = macarg (pfile, 0);
+	  if (token == CPP_EOF || token == CPP_POP)
+	    return;
+
+	  i++;
+	}
+      while (token == CPP_COMMA);
+    }
+}

gcc/testsuite/gcc.dg/uninit-4.c

+/* Spurious uninit variable warnings, case 4.
+   Simplified version of cppexp.c (cpp_parse_expr).
+
+   This one is really fragile, it gets it right if you take out case
+   1, or if the structure is replaced by an int, or if the structure
+   has fewer members (!) */
+
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+struct operation {
+    short op;
+    char rprio;
+    char flags;
+    char unsignedp;
+    long value;
+};
+
+extern struct operation cpp_lex (void);
+
+void
+cpp_parse_expr (void)
+{
+  int rprio; /* { dg-bogus "rprio" "uninitialized variable warning" { xfail *-*-* } } */
+  struct operation op;
+
+  for (;;)
+    {
+      op = cpp_lex ();
+
+      switch (op.op)
+	{
+	case 0:
+	  break;
+	case 1:
+	  return;
+	case 2:
+	  rprio = 1;
+	  break;
+	default:
+	  return;
+	}
+
+      if (op.op == 0)
+	return;
+
+      if (rprio != 1)
+	abort();
+    }
+}