tce-load -i compiletc cbindgen dbus-glib-dev gtk3-dev libnotify-dev node-dev nss-dev alsa-dev startup-notification-dev zip unzip libevent-dev libwebp1-dev clang libXt-dev curl-dev nasm libvpx113-dev python3.14-setuptools dav1d-dev libaom-dev

wget https://archive.mozilla.org/pub/firefox/releases/140.8.0esr/source/firefox-140.8.0esr.source.tar.xz
wget https://www.linuxfromscratch.org/patches/blfs/svn/firefox-140.8.0esr-python_3.14_fixes-1.patch

sudo cp /tmp/tcloop/clang/usr/local/bin/clang-19 /usr/local/bin
[..and need]
/usr/local/bin/clang -> clang-19
/usr/local/bin/clang++ -> clang

sudo ln -s /lib /lib64

cd firefox-140.8.0

patch -Np1 -i ../firefox-140.8.0esr-python_3.14_fixes-1.patch

cp mozconfig ./

export MACH_BUILD_PYTHON_NATIVE_PACKAGE_SOURCE=none
export MOZBUILD_STATE_PATH=${PWD}/mozbuild
./mach build [318:49.35]

export MACH_BUILD_PYTHON_NATIVE_PACKAGE_SOURCE=none
sudo ./mach install

sudo mkdir -pv /usr/local/share/applications
sudo mkdir -pv /usr/local/share/pixmaps

MIMETYPE="text/xml;text/mml;application/xhtml+xml"
MIMETYPE="$MIMETYPE;application/xhtml+xml;application/vnd.mozilla.xul+xml"
MIMETYPE="$MIMETYPE;x-scheme-handler/http;x-scheme-handler/https"

sudo cat > /usr/local/share/applications/firefox.desktop << EOF
[Desktop Entry]
Encoding=UTF-8
Name=Firefox Web Browser
Comment=Browse the World Wide Web
GenericName=Web Browser
Exec=firefox %u
Terminal=false
Type=Application
Icon=firefox
Categories=GNOME;GTK;Network;WebBrowser;
MimeType=$MIMETYPE
StartupNotify=true
EOF

unset MIMETYPE

In file included from Unified_cpp_intl_lwbrk0.cpp:2:
/usr/src/firefox-128.2.0/intl/lwbrk/LineBreaker.cpp:453:17: error: static assertion failed due to requirement 'U_LB_COUNT == mozilla::ArrayLength(sUnicodeLineBreakToClass)': Gecko vs ICU LineBreak class mismatch