ICU is not supported in this build. install from source code.

Install from source code(follow the manual)
system version: Ubuntu 22.04 LTS
pg version: PostgreSQL 15beta2 on x86_64-pc-linux-gnu, compiled by gcc
(Ubuntu 11.2.0-19ubuntu1) 11.2.0, 64-bit

install step:

> ./configure --with-perl --with-python --with-icu
> ICU_CFLAGS='-I/usr/include/unicode' ICU_LIBS='-L/usr/lib/icu'
> --enable-debug --with-pgport=5439
>
make world
> sudo su
> make install world
> mkdir -p /usr/local/pgsql/data
> chown jian /usr/local/pgsql/data
> su - jian
> /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
> /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data -l logfile start
> /usr/local/pgsql/bin/createdb test
> /usr/local/pgsql/bin/psql test
>

I installed ICU4C 71.1package.
use /usr/bin/icuinfo return

> <icuSystemParams type="icu4c">
> <param name="copyright"> Copyright (C) 2016 and later: Unicode, Inc.
> and others. License & terms of use: http://www.unicode.org/copyright.html
> </param>
> <param name="product">icu4c</param>
> <param name="product.full">International Components for Unicode for
> C/C++</param>
> <param name="version">71.1</param>
> <param name="version.unicode">14.0</param>
> <param name="platform.number">4000</param>
> <param name="platform.type">Linux</param>
> <param name="locale.default">en_US</param>
> <param name="locale.default.bcp47">en-US</param>
> <param name="converter.default">UTF-8</param>
> <param name="icudata.name">icudt71l</param>
> <param name="icudata.path"></param>
> <param name="cldr.version">41.0</param>
> <param name="tz.version">2022a</param>
> <param name="tz.default">Asia/Kolkata</param>
> <param name="cpu.bits">64</param>
> <param name="cpu.big_endian">0</param>
> <param name="os.wchar_width">4</param>
> <param name="os.charset_family">0</param>
> <param name="os.host">x86_64-pc-linux-gnu</param>
> <param name="build.build">x86_64-pc-linux-gnu</param>
> <param name="build.cc">gcc</param>
> <param name="build.cxx">g++</param>
> <param name="uconfig.internal_digitlist">1</param>
> <param name="uconfig.have_parseallinput">1</param>
> </icuSystemParams>
>
>
> ICU Initialization returned: U_ZERO_ERROR

Plugins are disabled.
>

But now I cannot ICU. when I create an collation related to ICU then

> ERROR: ICU is not supported in this build
>

--
I recommend David Deutsch's <<The Beginning of Infinity>>

Jian