QPROPERTY_TEST_COMPARISON_HELPER: fix mbstowcs and snprintf usage

The mbstowcs() function is not re-entrant, and while we can probably
rule out that our test macros are being executed concurrently, we
can't rule out that other parts of the test concurrently execute
std::mbstowcs().

To fix, de-inline the code so we can re-use the existing
formatFailMessage() in qtestresult.cpp, which has already been fixed
before.

Amends 930e59b798d9e3d08e17440980d33a08fb411cbe.

Pick-to: 6.8 6.7 6.5 6.2
Change-Id: I61144af13a41ea0b4fba17bd232e660ef33dbd20
Reviewed-by: Ivan Solovev <[email protected]>

3 files changed, 25 insertions, 13 deletions

diff --git a/src/testlib/qpropertytesthelper_p.h b/src/testlib/qpropertytesthelper_p.h
index 226de8e3fba..67314ec1a08 100644
--- a/src/testlib/qpropertytesthelper_p.h
+++ b/src/testlib/qpropertytesthelper_p.h
@@ -44,19 +44,15 @@ namespace QTestPrivate {
 */
 #define QPROPERTY_TEST_COMPARISON_HELPER(actual, expected, comparator, represent)                  \
     do {                                                                                           \
-        const size_t maxMsgLen = 1024;                                                             \
-        char msg[maxMsgLen];                                                                       \
-        auto actualStr = represent(actual);                                                        \
-        auto expectedStr = represent(expected);                                                    \
-        const size_t len1 = mbstowcs(nullptr, #actual, maxMsgLen);                                 \
-        const size_t len2 = mbstowcs(nullptr, #expected, maxMsgLen);                               \
-        qsnprintf(msg, maxMsgLen, "\n%s\n   Actual   (%s)%*s %s\n   Expected (%s)%*s %s\n",        \
-                  "Comparison failed!", #actual, qMax(len1, len2) - len1 + 1, ":",                 \
-                  actualStr ? actualStr : "<null>", #expected, qMax(len1, len2) - len2 + 1, ":",   \
-                  expectedStr ? expectedStr : "<null>");                                           \
-        delete[] actualStr;                                                                        \
-        delete[] expectedStr;                                                                      \
-        QVERIFY2(comparator(actual, expected), msg);                                               \
+        char qprop_tst_cmp_hlp_buf[1024]; \
+        const auto qprop_tst_cmp_hlp_act = std::unique_ptr<char[]>(represent(actual)); \
+        const auto qprop_tst_cmp_hlp_exp = std::unique_ptr<char[]>(represent(expected)); \
+        QVERIFY2(comparator(actual, expected), \
+                 QTest::Internal::formatPropertyTestHelperFailure(qprop_tst_cmp_hlp_buf, \
+                                                                  sizeof qprop_tst_cmp_hlp_buf, \
+                                                                  qprop_tst_cmp_hlp_act.get(), \
+                                                                  qprop_tst_cmp_hlp_exp.get(), \
+                                                                  #actual, #expected)); \
     } while (false)
 
 /*!
diff --git a/src/testlib/qtestcase.h b/src/testlib/qtestcase.h
index 44371c00a19..2c2c3263ff6 100644
--- a/src/testlib/qtestcase.h
+++ b/src/testlib/qtestcase.h
@@ -316,6 +316,11 @@ namespace QTest
     Q_TESTLIB_EXPORT void maybeThrowOnSkip();
 
     Q_TESTLIB_EXPORT QString formatTryTimeoutDebugMessage(q_no_char8_t::QUtf8StringView expr, int timeout, int actual);
+    Q_TESTLIB_EXPORT
+    const char *formatPropertyTestHelperFailure(char *msg, size_t maxMsgLen,
+                                                const char *actual, const char *expected,
+                                                const char *actualExpr,
+                                                const char *expectedExpr);
 
     template <ComparisonOperation> struct Compare;
     template <> struct Compare<ComparisonOperation::Equal>
diff --git a/src/testlib/qtestresult.cpp b/src/testlib/qtestresult.cpp
index 4feb0ac7044..6714d38ddf8 100644
--- a/src/testlib/qtestresult.cpp
+++ b/src/testlib/qtestresult.cpp
@@ -367,6 +367,17 @@ void formatFailMessage(char *msg, size_t maxMsgLen,
     }
 }
 
+const char *
+QTest::Internal::formatPropertyTestHelperFailure(char *msg, size_t maxMsgLen,
+                                                 const char *actual, const char *expected,
+                                                 const char *actualExpr, const char *expectedExpr)
+{
+    formatFailMessage(msg, maxMsgLen, "\nComparison failed!", // ### why leading \n?
+                      actual, expected, actualExpr, expectedExpr,
+                      QTest::ComparisonOperation::CustomCompare);
+    return msg;
+}
+
 // Format failures using the toString() template
 template <class Actual, class Expected>
 void formatFailMessage(char *msg, size_t maxMsgLen,