configure: detect ICU via icu-uc/icu-i18n pkg-config modules to easily build on Debian (#597)

Author: hugo-hur

.github/workflows/codeql-analysis.yml

@@ -69,7 +69,6 @@ jobs:
        sudo apt-get -q -y update
        sudo apt-get -q -y upgrade
        sudo apt-get -y install build-essential automake autoconf libtool pkg-config icu-devtools libicu-dev libxml2-dev uuid-dev fuse libfuse-dev libsnmp-dev
-       sudo cp .github/workflows/icu-config /usr/bin/icu-config
        ./autogen.sh
        ./configure
        make

.github/workflows/icu-config

@@ -290,16 +290,14 @@ You need to add `--enable-lintape` as an argument of ./configure script if you w
   | Ubuntu 16.04 LTS                   | ppc64le | OK - Not checked automatically                                                                                                   |
   | Ubuntu 18.04 LTS                   | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-ubuntu-bionic.yml/badge.svg) |
   | Ubuntu 18.04 LTS                   | ppc64le | OK - Not checked automatically                                                                                                   |
-  | Ubuntu 20.04 LTS (Need icu-config) | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-ubuntu-focal.yml/badge.svg) |
+  | Ubuntu 20.04 LTS                   | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-ubuntu-focal.yml/badge.svg) |
   | Debian 9                           | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-debian9.yml/badge.svg)        |
-  | Debian 10 (Need icu-config)        | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-debian10.yml/badge.svg)       |
+  | Debian 10                          | x86\_64 | ![GH Action status](https://github.com/LinearTapeFileSystem/ltfs/actions/workflows/build-debian10.yml/badge.svg)       |
   | ArchLinux 2018.08.01               | x86\_64 | OK - Not checked automatically                                                                                                   |
   | ArchLinux 2018.12.31 (rolling)     | x86\_64 | OK - Not checked automatically                                                                                                   |
 
 Currently, automatic build checking is working on GitHub Actions and Travis CI.
 
-For Ubuntu20.04 and Debian10, dummy `icu-config` is needed in the build machine. See Issue [#153](https://github.com/LinearTapeFileSystem/ltfs/issues/153).
-
 ### Build and install on OSX (macOS)
 
 #### Recent Homedrew system setup

README.md

@@ -6,7 +6,6 @@
 sudo apt-get -q -y update
 sudo apt-get -q -y upgrade
 sudo apt-get -y install build-essential automake autoconf libtool pkg-config libicu66 icu-devtools libicu-dev libxml2-dev uuid-dev fuse libfuse-dev libsnmp-dev
-sudo cp .github/workflows/icu-config /usr/bin/icu-config
 ./autogen.sh
 ./configure
 make

build.sh

@@ -339,12 +339,16 @@ fi
 
 dnl
 dnl Check for ICU
+dnl Prefer icu-config for legacy distros; fall back to pkg-config icu-uc/icu-i18n
+dnl (icu-config was removed in ICU 63+ and is absent on modern Debian/Ubuntu).
 dnl
 ICU_MODULE_CFLAGS="`icu-config --cppflags 2> /dev/null`";
 ICU_MODULE_LIBS="`icu-config --ldflags 2> /dev/null`";
 if test -z "$ICU_MODULE_LIBS"
 then
-    PKG_CHECK_MODULES([ICU_MODULE], [icu >= 0.21])
+    PKG_CHECK_MODULES([ICU_MODULE], [icu-uc >= 0.21 icu-i18n >= 0.21],
+        [],
+        [PKG_CHECK_MODULES([ICU_MODULE], [icu >= 0.21])])
 fi
 
 AC_MSG_CHECKING([use latest ICU])
@@ -359,6 +363,10 @@ if test "x${icu_6x}" = "xyes"
 then
     AC_MSG_CHECKING(for ICU version)
     ICU_MODULE_VERSION="`icu-config --version 2> /dev/null`";
+    if test -z "$ICU_MODULE_VERSION"
+    then
+        ICU_MODULE_VERSION="`$PKG_CONFIG --modversion icu-uc 2> /dev/null`";
+    fi
     if test "${ICU_MODULE_VERSION%%.*}" -ge "60"
     then
         AM_EXTRA_CPPFLAGS="${AM_EXTRA_CPPFLAGS} -D ICU6x"