Add tests with floating-point arguments for err* and verr* functions

Similarly to what has been done for argp_error, and argp_failure, as
well as for warn, warnx, vwarn, and vwarnx, this patch adds new tests
for the following functions: err, errx, verr, verrx, error, and
error_at_line.  The new tests check that the conversion of long double
variables into string works correctly on the default format of the type.
Future patches will reuse these tests for other formats that long double
can take.

Tested for powerpc64le.

	* misc/Makefile (tests): Add tst-ldbl-error.
	* misc/tst-ldbl-error.c: New file.

ChangeLog

@@ -1,3 +1,8 @@
+2018-11-06  Gabriel F. T. Gomes  <gabriel@inconstante.eti.br>
+
+	* misc/Makefile (tests): Add tst-ldbl-error.
+	* misc/tst-ldbl-error.c: New file.
+
 2018-11-06  Gabriel F. T. Gomes  <gabriel@inconstante.eti.br>
 
 	* misc/Makefile (tests): Add tst-ldbl-warn.

misc/Makefile

@@ -85,7 +85,7 @@ tests := tst-dirname tst-tsearch tst-fdset tst-efgcvt tst-mntent tst-hsearch \
 	 tst-mntent-blank-corrupt tst-mntent-blank-passno bug18240 \
 	 tst-preadvwritev tst-preadvwritev64 tst-makedev tst-empty \
 	 tst-preadvwritev2 tst-preadvwritev64v2 tst-warn-wide \
-	 tst-ldbl-warn
+	 tst-ldbl-warn tst-ldbl-error
 
 # Tests which need libdl.
 ifeq (yes,$(build-shared))

misc/tst-ldbl-error.c

@@ -0,0 +1,130 @@
+/* Test for the long double conversions in *err* functions.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <err.h>
+#include <errno.h>
+#include <error.h>
+#include <stdarg.h>
+#include <string.h>
+
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+
+struct tests
+{
+  void *callback;
+  const char *expected;
+};
+
+va_list args;
+
+static void
+callback_err (void *closure)
+{
+  errno = 0;
+  err (0, "%Lf", (long double) -1);
+}
+
+static void
+callback_errx (void *closure)
+{
+  errno = 0;
+  errx (0, "%Lf", (long double) -1);
+}
+
+static void
+callback_verr (void *closure)
+{
+  errno = 0;
+  verr (0, "%Lf", args);
+}
+
+static void
+callback_verrx (void *closure)
+{
+  errno = 0;
+  verrx (0, "%Lf", args);
+}
+
+static void
+callback_error (void *closure)
+{
+  errno = 0;
+  error (0, 0, "%Lf", (long double) -1);
+}
+
+static void
+callback_error_at_line (void *closure)
+{
+  errno = 0;
+  error_at_line (0, 0, "", 0, "%Lf", (long double) -1);
+}
+
+static void
+do_one_test (void *callback, const char *expected, ...)
+{
+  struct support_capture_subprocess result;
+
+  va_start (args, expected);
+
+  /* Call 'callback', which fills in the output and error buffers.  */
+  result = support_capture_subprocess (callback, NULL);
+
+  /* The functions err, errx, verr, and verrx print just the program
+     name followed by a colon, whereas error and error_at_line print the
+     whole path to the program.  Since the whole path depends on the
+     working directory used to build and test glibc, remove it from the
+     comparison against the expected result.  */
+  const char *needle = "tst-ldbl-error:";
+  char *message;
+  message = strstr (result.err.buffer, needle);
+
+  /* Verify that the output message is as expected.  */
+  if (strcmp (message, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error:\n"
+	      "    expected: '%s'\n"
+	      "      actual: '%s'\n",
+	      expected, message);
+    }
+
+  va_end (args);
+}
+
+static int
+do_test (void)
+{
+  struct tests tests[] = {
+    { &callback_err, "tst-ldbl-error: -1.000000: Success\n" },
+    { &callback_errx, "tst-ldbl-error: -1.000000\n" },
+    { &callback_verr, "tst-ldbl-error: -1.000000: Success\n" },
+    { &callback_verrx, "tst-ldbl-error: -1.000000\n" },
+    { &callback_error, "tst-ldbl-error: -1.000000\n" },
+    { &callback_error_at_line, "tst-ldbl-error::0: -1.000000\n" }
+  };
+
+  for (int i = 0; i < sizeof (tests) / sizeof (tests[0]); i++)
+    {
+      do_one_test (tests[i].callback, tests[i].expected, (long double) -1);
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>