From: Marco Falke <falke.marco@gmail.com>
Date: Tue, 19 Jul 2022 09:10:39 +0000 (+0100)
Subject: libstdc++: Make __from_chars_alnum_to_val conversion explicit
X-Git-Tag: releases/gcc-12.2.0~106
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0bb30f94ace6be68bd315d03f36b24bbaec2bee7;p=thirdparty%2Fgcc.git

libstdc++: Make __from_chars_alnum_to_val conversion explicit

The optimizations from commit r12-8175-ga54137c88061c7 introduced a
clang integer sanitizer error.

Fix this with an explicit static_cast, similar to the fix for PR 96766.

libstdc++-v3/ChangeLog:

	* include/std/charconv (__from_chars_alnum_to_val): Replace
	implicit conversion from int to unsigned char with explicit
	cast.

(cherry picked from commit 20ab3972240aff596a3fa98e9fb09ddc0658fbb3)
---

diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv
index 218813e4797f..533320ea0852 100644
--- a/libstdc++-v3/include/std/charconv
+++ b/libstdc++-v3/include/std/charconv
@@ -436,7 +436,7 @@ namespace __detail
     __from_chars_alnum_to_val(unsigned char __c)
     {
       if _GLIBCXX17_CONSTEXPR (_DecOnly)
-	return __c - '0';
+	return static_cast<unsigned char>(__c - '0');
       else
 	{
 	  // This initializer is deliberately made dependent in order to work