Add TEST_COMPARE_STRING_WIDE to support/check.h

I'd like to be able to test narrow and wide string interfaces, with
the narrow string tests using TEST_COMPARE_STRING and the wide string
tests using something analogous (possibly generated using macros from
a common test template for both the narrow and wide string tests where
appropriate).

Add such a TEST_COMPARE_STRING_WIDE, along with functions
support_quote_blob_wide and support_test_compare_string_wide that it
builds on.  Those functions are built using macros from common
templates shared by the narrow and wide string implementations, though
I didn't do that for the tests of test functions.  In
support_quote_blob_wide, I chose to use the \x{} delimited escape
sequence syntax proposed for C2X in N2785, rather than e.g. trying to
generate the end of a string and the start of a new string when
ambiguity would result from undelimited \x (when the next character
after such an escape sequence is valid hex) or forcing an escape
sequence to be used for the next character in the case of such
ambiguity.

Tested for x86_64.

1 files changed, 107 insertions, 0 deletions

diff --git a/support/tst-test_compare_string_wide.c b/support/tst-test_compare_string_wide.c
new file mode 100644
index 0000000000..548f7dcdc6
--- /dev/null
+++ b/support/tst-test_compare_string_wide.c
@@ -0,0 +1,107 @@
+/* Basic test for the TEST_COMPARE_STRING_WIDE macro.
+   Copyright (C) 2018-2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <support/check.h>
+#include <support/capture_subprocess.h>
+
+static void
+subprocess (void *closure)
+{
+  /* These tests should fail.  They were chosen to cover differences
+     in length (with the same contents), single-bit mismatches, and
+     mismatching null pointers.  */
+  TEST_COMPARE_STRING_WIDE (L"", NULL);             /* Line 29.  */
+  TEST_COMPARE_STRING_WIDE (L"X", L"");              /* Line 30.  */
+  TEST_COMPARE_STRING_WIDE (NULL, L"X");            /* Line 31.  */
+  TEST_COMPARE_STRING_WIDE (L"abcd", L"abcD");       /* Line 32.  */
+  TEST_COMPARE_STRING_WIDE (L"abcd", NULL);         /* Line 33.  */
+  TEST_COMPARE_STRING_WIDE (NULL, L"abcd");         /* Line 34.  */
+}
+
+/* Same contents, different addresses.  */
+wchar_t buffer_abc_1[] = L"abc";
+wchar_t buffer_abc_2[] = L"abc";
+
+static int
+do_test (void)
+{
+  /* This should succeed.  Even if the pointers and array contents are
+     different, zero-length inputs are not different.  */
+  TEST_COMPARE_STRING_WIDE (NULL, NULL);
+  TEST_COMPARE_STRING_WIDE (L"", L"");
+  TEST_COMPARE_STRING_WIDE (buffer_abc_1, buffer_abc_2);
+  TEST_COMPARE_STRING_WIDE (buffer_abc_1, L"abc");
+
+  struct support_capture_subprocess proc = support_capture_subprocess
+    (&subprocess, NULL);
+
+  /* Discard the reported error.  */
+  support_record_failure_reset ();
+
+  puts ("info: *** subprocess output starts ***");
+  fputs (proc.out.buffer, stdout);
+  puts ("info: *** subprocess output ends ***");
+
+  TEST_VERIFY
+    (strcmp (proc.out.buffer,
+"tst-test_compare_string_wide.c:29: error: string comparison failed\n"
+"  left string: 0 wide characters\n"
+"  right string: NULL\n"
+"tst-test_compare_string_wide.c:30: error: string comparison failed\n"
+"  left string: 1 wide characters\n"
+"  right string: 0 wide characters\n"
+"  left (evaluated from L\"X\"):\n"
+"      L\"X\"\n"
+"      58\n"
+"tst-test_compare_string_wide.c:31: error: string comparison failed\n"
+"  left string: NULL\n"
+"  right string: 1 wide characters\n"
+"  right (evaluated from L\"X\"):\n"
+"      L\"X\"\n"
+"      58\n"
+"tst-test_compare_string_wide.c:32: error: string comparison failed\n"
+"  string length: 4 wide characters\n"
+"  left (evaluated from L\"abcd\"):\n"
+"      L\"abcd\"\n"
+"      61 62 63 64\n"
+"  right (evaluated from L\"abcD\"):\n"
+"      L\"abcD\"\n"
+"      61 62 63 44\n"
+"tst-test_compare_string_wide.c:33: error: string comparison failed\n"
+"  left string: 4 wide characters\n"
+"  right string: NULL\n"
+"  left (evaluated from L\"abcd\"):\n"
+"      L\"abcd\"\n"
+"      61 62 63 64\n"
+"tst-test_compare_string_wide.c:34: error: string comparison failed\n"
+"  left string: NULL\n"
+"  right string: 4 wide characters\n"
+"  right (evaluated from L\"abcd\"):\n"
+"      L\"abcd\"\n"
+"      61 62 63 64\n"
+             ) == 0);
+
+  /* Check that there is no output on standard error.  */
+  support_capture_subprocess_check (&proc, "TEST_COMPARE_STRING_WIDE",
+                                    0, sc_allow_stdout);
+
+  return 0;
+}
+
+#include <support/test-driver.c>