[Chicken-janitors] #1322: Locale can influence how CHICKEN reads numbers

[Chicken Trac]

#1322: Locale can influence how CHICKEN reads numbers
----------------------------+-------------------------------
 Reporter:  sjamaan         |                 Owner:
     Type:  defect          |                Status:  new
 Priority:  major           |             Milestone:  4.12.0
Component:  unknown         |               Version:  4.11.0
 Keywords:  number parsing  |  Estimated difficulty:  hard
----------------------------+-------------------------------
 Because CHICKEN uses the libc `strtol`/`strtoll` and `strtod` functions
 when reading flonums and fixnums, locale settings may influence how
 CHICKEN reads numbers, especially in `decode_literal`.

 Hugo Arregui provided the following simple test:

 {{{
 ;; Compile this with the -embedded option, since it defines its own main()
 (import chicken scheme foreign)

 #>
 #include <locale.h>

 int main(int argc, char** argv) {
    setlocale(LC_NUMERIC, "es_AR.UTF-8");
    CHICKEN_run(C_toplevel);
    return 0;
 }
 <#

 (return-to-host)
 }}}

 This fails because the runtime system has several encoded floating-point
 numbers, which will no longer be read correctly.  Also note that `strtod`
 might incorrectly "parse" a floating-point number like `1.002` if it
 happens to be valid in the current locale using thousands separators.

 Parsing floating-point numbers in C is going to be pretty damn tricky, so
 we might just try and use `setlocale()` to set the locale to `C` and
 restore it to whatever it was before after doing so.  I have no idea what
 the effects are of calling these functions often in the same program, and
 if there's a performance impact (it might be loading the strings or
 formatting rules for this locale every single time, on the fly, since
 it'll be designed for "normal" programs in which `setlocale()` will be
 called only a handful of times)

--
Ticket URL: <https://bugs.call-cc.org/ticket/1322>
CHICKEN Scheme <https://www.call-cc.org/>
CHICKEN Scheme is a compiler for the Scheme programming language.