return value of from_chars with consumed characters

dune/common/std/charconv.hh

@@ -89,13 +89,15 @@ namespace Dune
         if (s.fail()) {
           if (value == std::numeric_limits<T>::max() || value == std::numeric_limits<T>::min())
             // range error
-            return from_chars_result{first + s.tellg(), std::errc::result_out_of_range};
+            return from_chars_result{s.eof() ? last : first, std::errc::result_out_of_range};
           else
             // extraction fails
             return from_chars_result{first, std::errc::invalid_argument};
         }
 
-        return from_chars_result{first + s.tellg(), std::errc{}};
+        // NOTE: Can not determine pointer to the first character not matching the pattern.
+        //       Returning last if all characters are consumed.
+        return from_chars_result{s.eof() ? last : first, std::errc{}};
       }
 
       template<typename T, typename StreamManipulator>

dune/common/strtonumber.hh

@@ -60,19 +60,17 @@ namespace Dune
         T value;
         auto result = Std::from_chars(first, last, value);
 
-        // require that all characters are consumed during conversion
-        char const* end = result.ptr;
-        bool all_consumed = (end != first);
-        while (all_consumed && (end != last) && (*end != '\0'))
-          all_consumed = std::isspace(*end++);
-
         if (result.ec == std::errc::result_out_of_range) {
           DUNE_THROW(RangeError, std::error_condition(result.ec).message());
         }
-        else if (result.ec == std::errc::invalid_argument || !all_consumed) {
+        else if (result.ec == std::errc::invalid_argument) {
           DUNE_THROW(InvalidArgument,
             "Conversion of '" << first << "' to number failed. Possible reason: invalid string or locale format.");
         }
+        else if (result.ptr != last) {
+          DUNE_THROW(InvalidArgument,
+            "Conversion of '" << first << "' to number failed. Not all characters consumed during conversion.");
+        }
         else if (result.ec == std::errc::not_supported) {
           DUNE_THROW(NotImplemented,
             "Parameter passed to from_chars not supported.");
@@ -84,7 +82,7 @@ namespace Dune
 
     /// \brief Implementation of a fallback parser using std::strtoXXX like functions
     /**
-     * Allows leading and trailing whitespace characters.
+     * Allows leading whitespace characters.
      * NOTE: This parser is not locale independent, but throws an error if whole
      *       string can not be parsed completely.
      *
@@ -108,14 +106,10 @@ namespace Dune
           DUNE_THROW(RangeError, std::strerror(old_errno));
         }
 
-        // test whether all non-space characters are consumed during conversion
-        bool all_consumed = (end != first);
-        while (all_consumed && (end != last) && (*end != '\0'))
-          all_consumed = std::isspace(*end++);
-
-        if (!all_consumed) {
+        // test whether all characters are consumed during conversion
+        if (end != last) {
           DUNE_THROW(InvalidArgument,
-            "Conversion of '" << first << "' to number failed. Possible reason: invalid string or locale format");
+            "Conversion of '" << first << "' to number failed. Possible reason: invalid string or locale format, or trailing characters.");
         }
 
         return convertToRange<T>(x);

dune/common/test/strtonumbertest.cc

@@ -211,7 +211,7 @@ int main()
     } catch(Dune::InvalidArgument const&) {
       exception = true;
     }
-    test.check(!exception, "InvalidArgument Exception: trailing whitespace");
+    test.check(exception, "InvalidArgument Exception: trailing whitespace");
 
     exception = false;
     try {