python3Packages.hdf5plugin: build ZFP filter against system zfp

H5Z-ZFP needs an 8-bit bitstream word for byte-portable data, so use a
zfp built with bitStreamWordSize=8. zfp ships only a CMake config, so
synthesise the pkg-config module hdf5plugin probes for.

Assisted-by: claude-code with claude-opus-4-8[1m]-high

pkgs/development/python-modules/hdf5plugin/default.nix

@@ -11,6 +11,7 @@
   bzip2,
   charls,
   lz4,
+  zfp,
   zlib,
   zstd,
   stdenv,
@@ -22,6 +23,8 @@
 
 let
   c-blosc' = c-blosc.override { snappySupport = true; };
+  # H5Z-ZFP needs an 8-bit bitstream word so the compressed HDF5 data is byte-portable
+  zfp' = zfp.override { bitStreamWordSize = 8; };
 in
 buildPythonPackage (finalAttrs: {
   pname = "hdf5plugin";
@@ -49,7 +52,7 @@ buildPythonPackage (finalAttrs: {
     bzip2
     charls
     lz4
-    # zfp
+    zfp'
     zlib
     zstd
   ];
@@ -62,7 +65,7 @@ buildPythonPackage (finalAttrs: {
     "charls"
     "lz4"
     # "sperr" # not packaged?
-    # "zfp" #  pkgconfig: (lib)zfp not found
+    "zfp"
     "zlib"
     "zstd"
   ];
@@ -86,9 +89,18 @@ buildPythonPackage (finalAttrs: {
   preBuild = ''
     mkdir src/hdf5plugin/plugins
 
-    mkdir -p pkg-config-bz2
-    ln -s ${lib.getDev bzip2}/lib/pkgconfig/bzip2.pc pkg-config-bz2/bz2.pc
-    export PKG_CONFIG_PATH="$PWD/pkg-config-bz2''${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}"
+    mkdir -p pkg-config
+    ln -s ${lib.getDev bzip2}/lib/pkgconfig/bzip2.pc pkg-config/bz2.pc
+    # zfp ships only a CMake config; synthesise the pkg-config module hdf5plugin probes for
+    {
+      echo "includedir=${lib.getDev zfp'}/include"
+      echo "Name: zfp"
+      echo "Version: ${zfp'.version}"
+      echo "Description: zfp"
+      echo "Libs: -L${lib.getLib zfp'}/lib -lzfp"
+      echo "Cflags: -I${lib.getDev zfp'}/include"
+    } > pkg-config/zfp.pc
+    export PKG_CONFIG_PATH="$PWD/pkg-config''${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}"
   '';
 
   meta = {