Re: [PATCH 2/2] libstdc++: Don't use std::tolower in <charconv> [PR103911]

[Jonathan Wakely <jwakely@redhat.com>]

On Sun, 1 May 2022 at 19:21, Patrick Palka via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> As in r12-6281-gc83ecfbe74a5cf for std::isdigit, <charconv> shouldn't
> use std::tolower either I think.
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk/11 and the
> 12 branch after it's thawed?

OK, thanks.

>
>         PR libstdc++/103911
>
> libstdc++-v3/ChangeLog:
>
>         * src/c++17/floating_from_chars.cc (find_end_of_float): Accept
>         two possible delimeters for the exponent part in the form of a
>         (possibly NULL) string of length two.  Don't use std::tolower.
>         (pattern): Adjust calls to find_end_of_float accordingly.
> ---
>  libstdc++-v3/src/c++17/floating_from_chars.cc | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
> index e7f3a58cf18..5d2a931d5dd 100644
> --- a/libstdc++-v3/src/c++17/floating_from_chars.cc
> +++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
> @@ -40,7 +40,6 @@
>  #include <cmath>
>  #include <cstdlib>
>  #include <cstring>
> -#include <cctype>
>  #include <locale.h>
>  #include <bits/functexcept.h>
>  #if _GLIBCXX_HAVE_XLOCALE_H
> @@ -142,10 +141,10 @@ namespace
>
>    // Find initial portion of [first, last) containing a floating-point number.
>    // The string `digits` is either `dec_digits` or `hex_digits`
> -  // and `exp` is 'e' or 'p' or '\0'.
> +  // and `exp` is "eE", "pP" or NULL.
>    const char*
>    find_end_of_float(const char* first, const char* last, const char* digits,
> -                   char exp)
> +                   const char *exp)
>    {
>      while (first < last && strchr(digits, *first) != nullptr)
>        ++first;
> @@ -155,7 +154,7 @@ namespace
>         while (first < last && strchr(digits, *first))
>           ++first;
>        }
> -    if (first < last && exp != 0 && std::tolower((unsigned char)*first) == exp)
> +    if (first < last && exp != nullptr && (*first == exp[0] || *first == exp[1]))
>        {
>         ++first;
>         if (first < last && (*first == '-' || *first == '+'))
> @@ -237,7 +236,7 @@ namespace
>
>         if ((last - first + 2) > buffer_resource::guaranteed_capacity())
>           {
> -           last = find_end_of_float(first + neg, last, digits, 'p');
> +           last = find_end_of_float(first + neg, last, digits, "pP");
>  #ifndef __cpp_exceptions
>             if ((last - first + 2) > buffer_resource::guaranteed_capacity())
>               {
> @@ -261,7 +260,7 @@ namespace
>         if ((last - first) > buffer_resource::guaranteed_capacity())
>           {
>             last = find_end_of_float(first + neg, last, digits,
> -                                    "e"[fmt == chars_format::fixed]);
> +                                    fmt == chars_format::fixed ? nullptr : "eE");
>  #ifndef __cpp_exceptions
>             if ((last - first) > buffer_resource::guaranteed_capacity())
>               {
> --
> 2.36.0.44.g0f828332d5
>