fdo#70319 "exponent followed by at least on digit" also for special case 0.0

Change-Id: I07e7917417b8a22cf6d64f2b7a447f9084b9fa2d

sal/qa/rtl/math/test-rtl-math.cxx

@@ -81,6 +81,12 @@ public:
         CPPUNIT_ASSERT_EQUAL(rtl_math_ConversionStatus_Ok, status);
         CPPUNIT_ASSERT_EQUAL(sal_Int32(RTL_CONSTASCII_LENGTH("1")), end);
         CPPUNIT_ASSERT_EQUAL(1.0, res);
+        res = rtl::math::stringToDouble(
+            rtl::OUString("0e"),
+            sal_Unicode('.'), sal_Unicode(','), &status, &end);
+        CPPUNIT_ASSERT_EQUAL(rtl_math_ConversionStatus_Ok, status);
+        CPPUNIT_ASSERT_EQUAL(sal_Int32(RTL_CONSTASCII_LENGTH("1")), end);
+        CPPUNIT_ASSERT_EQUAL(0.0, res);
     }
 
     CPPUNIT_TEST_SUITE(Test);

sal/rtl/math.cxx

@@ -819,6 +819,10 @@ inline double stringToDouble(CharT const * pBegin, CharT const * pEnd,
                 // offset
                 while (p != pEnd && rtl::isAsciiDigit(*p))
                     ++p;
+                if (p == pFirstExpDigit)
+                {   // no digits in exponent, reset end of scan
+                    p = pExponent;
+                }
             }
             else
             {