On Aug. 16th 2022
IME environment has been upgraded from "Fcitx' to "Fcitx5".

Thank you Patrick and Heinz Wiesinger for this update.
And also Thank you litelinux@linuxquestions_org for the tutorials of Fcitx5.

I updated my fcitx5-mozc package from 2.28.4800.102.1 to 2.28.4830.102.1.
Here is the SlackBuild of fcitx5-mozc package.
  version: 2.28.4830.102.1
  git-source: commit-be4da0c507f9bee9533d8dead5748d78fc767a11
  build requires: jdk11, bazel

fcitx5-mozc.SlackBuild
[code]
#!/bin/sh
# Slackware build script for fcitx-mozc
# Issued under The MIT License (MIT)
#
# Copyright 2016 Kuro_CODE25
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

PRGNAM=fcitx5-mozc
VERSION=${VERSION:-2.28.4830.102.1}
BUILD=${BUILD:-1}
TAG=${TAG:-jw}

if [ -z "$ARCH" ]; then
  case "$( uname -m )" in
    i?86) ARCH=i586 ;;
    arm*) ARCH=arm ;;
       *) ARCH=$( uname -m ) ;;
  esac
fi

CWD=$(pwd)
TMP=${TMP:-/tmp/SBo}
PKG=$TMP/package-$PRGNAM
OUTPUT=${OUTPUT:-/tmp}
BLDBASEDIR=$TMP/$PRGNAM-$VERSION

if [ "$ARCH" = "i586" ]; then
  SLKCFLAGS="-O2 -march=i586 -mtune=i686"
  LIBDIRSUFFIX=""
elif [ "$ARCH" = "i686" ]; then
  SLKCFLAGS="-O2 -march=i686 -mtune=i686"
  LIBDIRSUFFIX=""
elif [ "$ARCH" = "x86_64" ]; then
  SLKCFLAGS="-O2 -fPIC"
  LIBDIRSUFFIX="64"
else
  SLKCFLAGS="-O2"
  LIBDIRSUFFIX=""
fi

set -e
BLDTYPE=Release
# source rev. and version.
ZIPCODE_REL=202110
ABSEIL_CPP_REV=eb3db08cb3a4faf2aa09a2ba4a30b442457f36cf
BREAKPAD_REV=c685fe1153193853cff23e83d6d2b2c577aaa5f6
GOOGLETEST_REV=703bd9caab50b139428cea1aaff9974ebee5742e
JSONCPP_REV=42e892d96e47b1f6e29844cc705e148ec4856448
PROTOBUF_REV=b5a35bcc7e4cc4ff00eb105449b300fca3a8b0d2
GYP_REV=caa60026e223fc501e8b337fd5086ece4028b1c6
JAPANESE_USAGE_DICT_REV=e5b3425575734c323e1d947009dd74709437b684
# 2.28.4800  MOZC_REV=9eadd16fc0a4f9010be1be5ba182c6aed42eb65b
MOZC_REV=be4da0c507f9bee9533d8dead5748d78fc767a11

# Download sources
wget https://github.com/chromium/gyp/archive/${GYP_REV}/gyp-${GYP_REV}.zip
wget https://github.com/fcitx/mozc/archive/${MOZC_REV}/mozc-${MOZC_REV}.zip
wget https://github.com/hiroyuki-komatsu/japanese-usage-dictionary/archive/${JAPANESE_USAGE_DICT_REV}/japanese-usage-dictionary-${JAPANESE_USAGE_DICT_REV}.zip
wget https://github.com/protocolbuffers/protobuf/archive/${PROTOBUF_REV}/protobuf-${PROTOBUF_REV}.zip
wget https://github.com/abseil/abseil-cpp/archive/${ABSEIL_CPP_REV}/abseil-cpp-${ABSEIL_CPP_REV}.zip
wget https://chromium.googlesource.com/breakpad/breakpad/+archive/${BREAKPAD_REV}.tar.gz
wget https://github.com/google/googletest/archive/${GOOGLETEST_REV}/googletest-${GOOGLETEST_REV}.zip
wget https://github.com/open-source-parsers/jsoncpp/archive/${JSONCPP_REV}/jsoncpp-${JSONCPP_REV}.zip

wget https://osdn.net/projects/ponsfoot-aur/storage/mozc/jigyosyo-${ZIPCODE_REL}.zip
wget https://osdn.net/projects/ponsfoot-aur/storage/mozc/x-ken-all-${ZIPCODE_REL}.zip
wget https://download.fcitx-im.org/fcitx-mozc/fcitx-mozc-icon.tar.gz

rm -rf $PKG
mkdir -p $TMP $PKG $OUTPUT
cd $TMP
rm -rf $PRGNAM-$VERSION
mkdir -p $PRGNAM-$VERSION
cd $PRGNAM-$VERSION
echo "prepare source file..."
# unzip packages
unzip $CWD/x-ken-all-$ZIPCODE_REL.zip
unzip $CWD/jigyosyo-$ZIPCODE_REL.zip
unzip $CWD/abseil-cpp-$ABSEIL_CPP_REV.zip
unzip $CWD/googletest-$GOOGLETEST_REV.zip
unzip $CWD/jsoncpp-$JSONCPP_REV.zip
unzip $CWD/mozc-$MOZC_REV.zip
unzip $CWD/japanese-usage-dictionary-$JAPANESE_USAGE_DICT_REV.zip
unzip $CWD/gyp-$GYP_REV.zip
unzip $CWD/protobuf-$PROTOBUF_REV.zip
# untar breakpad to breakpad directory
mkdir breakpad
tar xvf ${CWD}/${BREAKPAD_REV}.tar.gz -C breakpad

# extact tar file
tar -xvf ${CWD}/fcitx-mozc-icon.tar.gz

# rename directory
mv mozc-$MOZC_REV mozc
mv gyp-$GYP_REV gyp
mv japanese-usage-dictionary-$JAPANESE_USAGE_DICT_REV japanese_usage_dictionary
mv abseil-cpp-$ABSEIL_CPP_REV abseil-cpp
mv protobuf-$PROTOBUF_REV protobuf
#mv breakpad-$BREAKPAD_REV breakpad
mv googletest-$GOOGLETEST_REV googletest
mv jsoncpp-$JSONCPP_REV jsoncpp

chown -R root:root .
find -L . \
 \( -perm 777 -o -perm 775 -o -perm 750 -o -perm 711 -o -perm 555 \
  -o -perm 511 \) -exec chmod 755 {} \; -o \
 \( -perm 666 -o -perm 664 -o -perm 640 -o -perm 600 -o -perm 444 \
  -o -perm 440 -o -perm 400 \) -exec chmod 644 {} \;

cd $BLDBASEDIR/mozc/src

# disable fcitx4 target
#rm unix/fcitx/fcitx.gyp

# disable android-ndk requirement, even if we don't need it bazel will complain
sed "/android_ndk_repository/d" -i WORKSPACE.bazel

# adjust QT_BASE_PATH
sed 's|path = QT_BASE_PATH|path = "/usr/include/qt5"|' -i WORKSPACE.bazel

cd $BLDBASEDIR/mozc
# prepare zip code dictionary
unzip -d src/data/dictionary_oss $CWD/x-ken-all-$ZIPCODE_REL.zip
unzip -d src/data/dictionary_oss $CWD/jigyosyo-$ZIPCODE_REL.zip

cd src/dictionary
# Generate zip code seed
sed -i "s/from dictionary import zip_code_util/import zip_code_util/g" gen_zip_code_seed.py

cd ../data/dictionary_oss
echo "Generating zip code seed ..."
python3 ../../dictionary/gen_zip_code_seed.py --zip_code=x-ken-all.csv --jigyosyo=JIGYOSYO.CSV >> dictionary09.txt
echo "Done."

# Copy third party deps
echo "Copy third party deps ..."
cd $BLDBASEDIR/mozc
# fix QT_BBASE_PATH QT_BIN_PATH
#patch -p1 < $CWD/01_mozc_config.bzl_qt5.diff
#
# 2022-07-07 # For Linux, Qt paths are managed by pkg_config_repository in WORKSPACE.bazel.
# So, we don't need 01_mozc_config.bzl_qt5.diff.

# fix libdir path of fcitx5-mozc.so for Slackware
patch -p1 < $CWD/02_install_fcitx5_libdir.diff

cd ..
for dep in abseil-cpp breakpad googletest jsoncpp gyp protobuf japanese_usage_dictionary
do
  cp -a $dep mozc/src/third_party/
done

# build package
echo "build package..."
CFLAGS="${CFLAGS} -fvisibility=hidden"
CXXFLAGS="${CXXFLAGS} -fvisibility=hidden"

cd $BLDBASEDIR/mozc/src
QT_BASE_PATH=/usr/include/qt5 bash ../scripts/build_fcitx5_bazel

# Build emacs_helper
echo "build emacs_helper..."

# export JAVA_HOME
export JAVA_HOME=/usr/lib64/jdk11-11.0.14
# Build
bazel build unix/emacs:mozc_emacs_helper --config oss_linux --compilation_mode opt

# Extract license part of mozc
head -n 29 server/mozc_server.cc > LICENSE

export PREFIX="$PKG/usr"
export _bldtype
bash ../scripts/install_server_bazel

install -d "$PKG/usr/share/licenses/${PRGNAM}/"
install -m 644 LICENSE data/installer/*.html "$PKG/usr/share/licenses/${PRGNAM}/"

install -d "${PREFIX}/share/fcitx5/addon"
install -d "${PREFIX}/share/fcitx5/inputmethod"
install -d "${PREFIX}/lib${LIBDIRSUFFIX}/fcitx5"
bash ../scripts/install_fcitx5_bazel

# Install emacs_helper
install -Dm644 ../LICENSE $PKG/usr/share/licenses/emacs-mozc/LICENSE
install -Dm644 data/installer/credits_en.html  $PKG/usr/share/licenses/emacs-mozc/credits_en.html
install -Dm755 bazel-bin/unix/emacs/mozc_emacs_helper $PKG/usr/bin/mozc_emacs_helper
install -Dm644 unix/emacs/mozc.el $PKG/usr/share/emacs/site-lisp/mozc.el

mkdir -p $PKG/usr/doc/$PRGNAM-$VERSION

cp $CWD/sources.url $CWD/init.el_mozc $CWD/README.emacs $PKG/usr/doc/$PRGNAM-$VERSION/
cp $CWD/*.diff $PKG/usr/doc/$PRGNAM-$VERSION/
cp $CWD/$PRGNAM.SlackBuild $PKG/usr/doc/$PRGNAM-$VERSION/$PRGNAM.SlackBuild

mkdir -p $PKG/install
# install slack-desc
cat $CWD/slack-desc > $PKG/install/slack-desc

### clean-up work directory
echo "Clean up working directory ..."
#for dep in abseil-cpp breakpad googletest jsoncpp gyp protobuf japanese_usage_dictionary
#do
#  rm -rf $CWD/$dep
#done
rm -rf $CWD/*.zip $CWD/*.tar.gz

cd $PKG
/sbin/makepkg -l y -c n $OUTPUT/$PRGNAM-$VERSION-$ARCH-$BUILD$TAG.${PKGTYPE:-txz}


01_mozc_config.bzl_qt5.diff
# 2022-07-07 # For Linux, Qt paths are managed by pkg_config_repository in WORKSPACE.bazel.
# So, we don't need 01_mozc_config.bzl_qt5.diff.
[code]
--- a/src/config.bzl    2022-03-21 13:54:26.000000000 +0900
+++ b/src/config.bzl    2022-03-26 15:14:04.384298439 +0900
@@ -40,8 +40,8 @@
 MACOS_MIN_OS_VER = "10.12"
 
 ## Qt paths
-QT_BASE_PATH = "/usr/include/x86_64-linux-gnu/qt5"  # For Debian
-QT_BIN_PATH = "/usr/bin/"
+QT_BASE_PATH = "/usr/include/qt5"  # For Slackware
+QT_BIN_PATH = "/usr/lib64/qt5/bin/"
 
 ## For macOS
 ## QT_BASE_PATH should be a directory compiled with -developer_build option.


02_install_fcitx5_libdir.diff
[code]
--- a/scripts/install_fcitx5_bazel    2022-03-26 17:59:59.265593030 +0900
+++ b/scripts/install_fcitx5_bazel    2022-03-26 18:00:47.135593436 +0900
@@ -1,7 +1,7 @@
 #!/bin/sh
 PREFIX="${PREFIX:-/usr}"
 
-install -D -m 755 "bazel-bin/unix/fcitx5/fcitx5-mozc.so" "${PREFIX}/lib/fcitx5/fcitx5-mozc.so"
+install -D -m 755 "bazel-bin/unix/fcitx5/fcitx5-mozc.so" "${PREFIX}/lib64/fcitx5/fcitx5-mozc.so"
 
 PREFIX="${PREFIX}" ../scripts/install_fcitx5_data
 PREFIX="${PREFIX}" ../scripts/install_fcitx5_icons


init.el_mozc
[code]
(set-language-environment "Japanese")
(require 'mozc)  ; or (load-file "/usr/share/emacs/site-lisp/emacs-mozc/mozc.el")
(setq default-input-method "japanese-mozc")
(setq mozc-candidate-style 'overlay)


README.emacs
[code]
# for emacs, create {HOME}/.emacs.d/init.el with followng lines

(require 'mozc)  ; or (load-file "/path/to/mozc.el")
(setq default-input-method "japanese-mozc")
(setq mozc-candidate-style 'overlay)


slack-desc
[code]
# HOW TO EDIT THIS FILE:
# The "handy ruler" below makes it easier to edit a package description.
# Line up the first '|' above the ':' following the base package name, and
# the '|' on the right side marks the last column you can put a character in.
# You must make exactly 11 lines for the formatting to be correct.  It's also
# customary to leave one space after the ':' except on otherwise blank lines.

           |-----handy-ruler------------------------------------------------------|
fcitx5-mozc: fcitx5-mozc (Mozc engine for fcitx5)
fcitx5-mozc:
fcitx5-mozc: fcitx5-mozc is Mozc, Japanese input method editor, engine for fcitx5.
fcitx5-mozc:
fcitx5-mozc: Homepage: https://fcitx-im.org
fcitx5-mozc:
fcitx5-mozc:
fcitx5-mozc:
fcitx5-mozc:
fcitx5-mozc:
fcitx5-mozc:


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