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QLatin1String: fix qt_compare_strings(QLatin1String, QLatin1String) for null strings 

qstrcmp sorts null strings before empty ones, while the Qt string
classes consider them equal.

The qt_compare_strings() overload for QLatin1String was using
qstrcmp(), but is supposed to implement the semantics that Qt string
classes use, so we need to add an extra check.

Was uncovered by tests for QLatin1String::startsWith(), but added a
new test for qCompareStrings() now, which is a bit more complicated
than desired, due to the lack of QUtf8String.

Change-Id: I0493c4491df928a68861a1bc7f0962f1c870a416
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
bb10
Marc Mutz 2017-04-24 09:54:02 +02:00
parent 5677b70eee
commit 979f9f4d34
2 changed files with 42 additions and 0 deletions
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2
src/corelib/tools/qstring.cpp
View File

@ -695,6 +695,8 @@ static int qt_compare_strings(QStringView lhs, QLatin1String rhs, Qt::CaseSensit
static int qt_compare_strings(QLatin1String lhs, QLatin1String rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
if (lhs.isEmpty())
return lencmp(0, rhs.size());
const auto l = std::min(lhs.size(), rhs.size());
int r;
if (cs == Qt::CaseSensitive)

40
tests/auto/corelib/tools/qstringapisymmetry/tst_qstringapisymmetry.cpp
View File

@ -319,6 +319,9 @@ void tst_QStringApiSymmetry::compare_data(bool hasConceptOfNullAndEmpty)
QTest::newRow("null <> empty") << QStringRef() << QLatin1String()
<< QStringRef(&empty) << QLatin1String("")
<< 0 << 0;
QTest::newRow("empty <> null") << QStringRef(&empty) << QLatin1String("")
<< QStringRef() << QLatin1String()
<< 0 << 0;
}
#define ROW(lhs, rhs) \
@ -362,6 +365,38 @@ struct has_nothrow_compare {
enum { value = is_utf8_encoded<LHS>::value == is_utf8_encoded<RHS>::value };
};
template <typename LHS, typename RHS>
struct has_qCompareStrings {
enum { value = !std::is_same<LHS, QChar>::value && !std::is_same<RHS, QChar>::value &&
!is_utf8_encoded<LHS>::value && !is_utf8_encoded<RHS>::value };
};
template <typename LHS, typename RHS>
using if_has_qCompareStrings = typename std::enable_if<has_qCompareStrings<LHS, RHS>::value, bool>::type;
template <typename LHS, typename RHS>
using if_lacks_qCompareStrings = typename std::enable_if<!has_qCompareStrings<LHS, RHS>::value, bool>::type;
static inline Q_DECL_CONSTEXPR int sign(int x) Q_DECL_NOTHROW
{
return x < 0 ? -1 :
x > 0 ? +1 :
/*else*/ 0 ;
}
template <typename LHS, typename RHS, if_has_qCompareStrings<LHS, RHS> = true>
int qCompareStringsWrapper(const LHS &lhs, const RHS &rhs, Qt::CaseSensitivity cs, int)
Q_DECL_NOEXCEPT_EXPR(noexcept(qCompareStrings(lhs, rhs, cs)))
{
return qCompareStrings(lhs, rhs, cs);
}
template <typename LHS, typename RHS, if_lacks_qCompareStrings<LHS, RHS> = true>
int qCompareStringsWrapper(const LHS &, const RHS &, Qt::CaseSensitivity, int result)
{
return result;
}
template <typename LHS, typename RHS>
void tst_QStringApiSymmetry::compare_impl() const
{
@ -370,6 +405,7 @@ void tst_QStringApiSymmetry::compare_impl() const
QFETCH(QStringRef, rhsUnicode);
QFETCH(QLatin1String, rhsLatin1);
QFETCH(int, caseSensitiveCompareResult);
QFETCH(const int, caseInsensitiveCompareResult);
const auto lhsU8 = lhsUnicode.toUtf8();
const auto rhsU8 = rhsUnicode.toUtf8();
@ -386,6 +422,10 @@ void tst_QStringApiSymmetry::compare_impl() const
# define QVERIFY_NOEXCEPT(expr)
#endif
QCOMPARE(sign(qCompareStringsWrapper(lhs, rhs, Qt::CaseSensitive, caseSensitiveCompareResult)),
sign(caseSensitiveCompareResult));
QCOMPARE(sign(qCompareStringsWrapper(lhs, rhs, Qt::CaseInsensitive, caseInsensitiveCompareResult)),
sign(caseInsensitiveCompareResult));
#define CHECK(op) \
QVERIFY_NOEXCEPT(lhs op rhs); \
do { if (caseSensitiveCompareResult op 0) { \