QmlCompiler: Implement Math.pow()

Also, add missing positive infinity to test data.

Pick-to: 6.4
Fixes: QTBUG-104745
Change-Id: I958aca672cca8cc83c540ed3ea75b08e70eb90fd
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/qml/jsapi/qjsprimitivevalue.cpp

@@ -280,5 +280,16 @@ QString QJSPrimitiveValue::toString(double d)
     return result;
 }
 
+/*!
+  \fn double QQmlPrivate::jsExponentiate(double base, double exponent)
+  \internal
+  \since 6.4
+
+  Performs JavaScript's Number::exponentiate operation on \a base and
+  \a exponent, and returns the result.
+
+  See https://tc39.es/ecma262/multipage/ecmascript-data-types-and-values.html#sec-numeric-types-number-exponentiate
+ */
+
 QT_END_NAMESPACE
 

src/qml/jsapi/qjsprimitivevalue.h

@@ -783,6 +783,37 @@ private:
     QJSPrimitiveValuePrivate d;
 };
 
+namespace QQmlPrivate {
+    // TODO: Make this constexpr once std::isnan is constexpr.
+    inline double jsExponentiate(double base, double exponent)
+    {
+        constexpr double qNaN = std::numeric_limits<double>::quiet_NaN();
+        constexpr double inf = std::numeric_limits<double>::infinity();
+
+        if (qIsNull(exponent))
+            return 1.0;
+
+        if (std::isnan(exponent))
+            return qNaN;
+
+        if (QJSNumberCoercion::equals(base, 1.0) || QJSNumberCoercion::equals(base, -1.0))
+            return std::isinf(exponent) ? qNaN : std::pow(base, exponent);
+
+        if (!qIsNull(base))
+            return std::pow(base, exponent);
+
+        if (std::copysign(1.0, base) > 0.0)
+            return exponent < 0.0 ? inf : std::pow(base, exponent);
+
+        if (exponent < 0.0)
+            return QJSNumberCoercion::equals(std::fmod(-exponent, 2.0), 1.0) ? -inf : inf;
+
+        return QJSNumberCoercion::equals(std::fmod(exponent, 2.0), 1.0)
+                ? std::copysign(0, -1.0)
+                : 0.0;
+    }
+}
+
 QT_END_NAMESPACE
 
 #endif // QJSPRIMITIVEVALUE_H

src/qmlcompiler/qqmljscodegenerator.cpp

@@ -1320,6 +1320,7 @@ bool QQmlJSCodeGenerator::inlineMathMethod(const QString &name, int argc, int ar
     addInclude(u"limits"_s);
     addInclude(u"qalgorithms.h"_s);
     addInclude(u"qrandom.h"_s);
+    addInclude(u"qjsprimitivevalue.h"_s);
 
     // If the result is not stored, we don't need to generate any code. All the math methods are
     // conceptually pure functions.
@@ -1403,8 +1404,7 @@ bool QQmlJSCodeGenerator::inlineMathMethod(const QString &name, int argc, int ar
                 "? arg2 "
                 ": ((arg2 < arg1 || std::isnan(arg2)) ? arg2 : arg1)"_s;
     } else if (name == u"pow"_s) {
-        // TODO: complicated
-        return false;
+        expression = u"QQmlPrivate::jsExponentiate(arg1, arg2)"_s;
     } else if (name == u"random"_s && argc == 0) {
         expression = u"QRandomGenerator::global()->generateDouble()"_s;
     } else if (name == u"round"_s && argc == 1) {

tests/auto/qml/qmlcppcodegen/data/jsMathObject.qml

@@ -32,7 +32,7 @@ QtObject {
     property double log2: Math.log2(a)
     property double max: Math.max(a, b)
     property double min: Math.min(a, b)
-//    property double pow: Math.pow(a, b)
+    property double pow: Math.pow(a, b)
     property double random: Math.random()
     property double round: Math.round(a)
     property double sign: Math.sign(a)

tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp

@@ -1606,6 +1606,7 @@ void tst_QmlCppCodegen::jsMathObject()
         std::numeric_limits<quint32>::max(),
         std::numeric_limits<float>::max(),
         std::numeric_limits<double>::max(),
+        qInf()
     };
 
     QJSManagedValue math(engine.globalObject().property(QStringLiteral("Math")), &engine);