setlenient=true, get LC_TIME locale

libgnucash/engine/gnc-datetime.cpp

@@ -616,26 +616,44 @@ GncDateTimeImpl::timestamp()
     return str.substr(0, 8) + str.substr(9, 15);
 }
 
+static icu::Locale
+get_LCTIME_locale()
+{
+    const char* lc_time_locale = setlocale(LC_TIME, nullptr);
+
+    if (lc_time_locale == nullptr)
+        return icu::Locale::getDefault();
+
+    std::string localeStr(lc_time_locale);
+    size_t dotPos = localeStr.find('.');
+    if (dotPos != std::string::npos)
+        localeStr = localeStr.substr(0, dotPos);
+
+    return icu::Locale::createCanonical (localeStr.c_str());
+}
+
 static Date
 use_icu_parser (const std::string str)
 {
     UErrorCode status = U_ZERO_ERROR;
-    icu::Locale locale;
-    std::unique_ptr<icu::DateFormat> formatter(icu::DateFormat::createDateInstance(icu::DateFormat::kDefault, locale));
+    icu::Locale locale = get_LCTIME_locale();
+
+    static std::unique_ptr<icu::DateFormat> formatter(icu::DateFormat::createDateInstance(icu::DateFormat::kDefault, locale));
     if (formatter == nullptr)
         throw std::invalid_argument ("Cannot create date formatter.");
 
+    static std::unique_ptr<icu::Calendar> calendar(icu::Calendar::createInstance(locale, status));
+    if (U_FAILURE(status))
+        throw std::invalid_argument("Cannot create calendar instance.");
+    calendar->setLenient (false);
+
     icu::UnicodeString input = icu::UnicodeString::fromUTF8(str);
     icu::ParsePosition parsePos;
 
     UDate date = formatter->parse(input, parsePos);
-    if (parsePos.getErrorIndex() != -1)
+    if (parsePos.getErrorIndex() != -1 || parsePos.getIndex() != input.length())
         throw std::invalid_argument ("Cannot parse string");
 
-    std::unique_ptr<icu::Calendar> calendar(icu::Calendar::createInstance(locale, status));
-    if (U_FAILURE(status))
-        throw std::invalid_argument("Cannot create calendar instance.");
-
     calendar->setTime(date, status);
     if (U_FAILURE(status))
         throw std::invalid_argument ("Cannot set calendar time");