Possibly incorrect downcasting of separator_

[sffc]

The template type Iterator is used throughout double-conversion.cpp. It appears that Iterator can be one of two types:

• const uc16*
• const char*

There is a function Advance whose signature is:

template<class Iterator>
static bool Advance (Iterator* it, char separator, int base, Iterator& end)

The call sites look like this:

// current is of type Iterator
Advance(&current, separator_, 10, end)

The problem is that separator_ is being downcast to a char even when using the uc16* template type for the string. The implication is that there is a possible loss of information; for example, the separator might be a Unicode code point that doesn't fit in a char. A great real-life example could be 'NARROW NO-BREAK SPACE' (U+202F), which is now used in CLDR as the default grouping separator in France.

The code should be checked to ensure that separator_ is not downcast to a char unless the iterator is a char iterator.

[floitsch]

Will look into it.
Don't hesitate to ping from time to time (~ once a week?) to make sure I don't forget.

[sffc]

Thank you!