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

[Patrick Palka via Gcc-patches]

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?

        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