From 32944bbdbf2c7611e72ec9828464978ca42824ce Mon Sep 17 00:00:00 2001
From: Jakob Kukla <jakob.kukla@gmail.com>
Date: Fri, 12 Sep 2025 10:31:22 +0000
Subject: [PATCH] cmake: support absolute paths for install dirs in pkg-config

The GNUInstallDirs module supports absolute paths for CMAKE_INSTALL_LIBDIR and CMAKE_INSTALL_INCLUDEDIR. Some package managers like Nix depend on this behaviour. See https://github.com/NixOS/nixpkgs/issues/144170 for the nixpkgs tracking issue.
---
 host/CMakeLists.txt | 12 ++++++++++++
 host/uhd.pc.in      |  4 ++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/host/CMakeLists.txt b/host/CMakeLists.txt
index 3e93ea1f0c..4cd0afad9d 100644
--- a/host/CMakeLists.txt
+++ b/host/CMakeLists.txt
@@ -559,6 +559,18 @@ if(CMAKE_CROSSCOMPILING)
     set(UHD_PC_LIBS)
 endif(CMAKE_CROSSCOMPILING)
 
+# Support absolute paths for LIBDIR and INCLUDEDIR
+if(IS_ABSOLUTE "${CMAKE_INSTALL_LIBDIR}")
+    set(UHD_PC_LIBDIR "${CMAKE_INSTALL_LIBDIR}")
+else()
+    set(UHD_PC_LIBDIR "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
+endif()
+if(IS_ABSOLUTE "${CMAKE_INSTALL_INCLUDEDIR}")
+    set(UHD_PC_INCLUDEDIR "${CMAKE_INSTALL_INCLUDEDIR}")
+else()
+    set(UHD_PC_INCLUDEDIR "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
+endif()
+
 configure_file(
     ${CMAKE_CURRENT_SOURCE_DIR}/uhd.pc.in
     ${CMAKE_CURRENT_BINARY_DIR}/uhd.pc
diff --git a/host/uhd.pc.in b/host/uhd.pc.in
index 4a5f67c969..f121e2fb70 100644
--- a/host/uhd.pc.in
+++ b/host/uhd.pc.in
@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${exec_prefix}/@CMAKE_INSTALL_LIBDIR@
-includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
+libdir=@UHD_PC_LIBDIR@
+includedir=@UHD_PC_INCLUDEDIR@
 
 Name: @CPACK_PACKAGE_NAME@
 Description: @CPACK_PACKAGE_DESCRIPTION_SUMMARY@