From 81c6b8823c1b58d7837e827bb1098aa5f9e5956b Mon Sep 17 00:00:00 2001
From: "Jeremy W. Murphy" <jeremy.william.murphy@gmail.com>
Date: Tue, 16 May 2023 05:07:36 +1000
Subject: [PATCH] cmake: Only use relative paths for install DESTINATION option
 (#1405)

As described in #1404, the explicit use of CMAKE_INSTALL_PREFIX conflicts with using command-line --prefix.

This simply removes all explicit use of CMAKE_INSTALL_PREFIX.

Otherwise this path will be duplicated:

    $ cmake -DCMAKE_BUILD_TYPE=debug -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_INSTALL_PREFIX=inst ..
    $ DESTDIR=inst ninja install
    ...
    -- Installing: inst/src/le/libevent/.cmake-debug/inst/include/event2/util.h
    -- Installing: inst/src/le/libevent/.cmake-debug/inst/include/event2/ws.h
    ...

Fixes: #1404
Co-authored-by: Jeremy Murphy <jeremymu@blackmagicdesign.com>
---
 CMakeLists.txt              | 3 +--
 cmake/AddEventLibrary.cmake | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1452,8 +1452,7 @@ endif()
 # Installation preparation.
 #
 
-set(EVENT_INSTALL_CMAKE_DIR
-    "${CMAKE_INSTALL_PREFIX}/lib/cmake/libevent")
+set(EVENT_INSTALL_CMAKE_DIR "lib/cmake/libevent")
 
 export(PACKAGE libevent)
 
--- a/cmake/AddEventLibrary.cmake
+++ b/cmake/AddEventLibrary.cmake
@@ -31,7 +31,7 @@ macro(generate_pkgconfig LIB_NAME)
     configure_file("lib${LIB_NAME}.pc.in" "lib${LIB_NAME}.pc" @ONLY)
     install(
         FILES "${CMAKE_CURRENT_BINARY_DIR}/lib${LIB_NAME}.pc"
-        DESTINATION "${CMAKE_INSTALL_PREFIX}/lib/pkgconfig"
+        DESTINATION "lib/pkgconfig"
     )
 endmacro()
 
@@ -150,7 +150,7 @@ macro(add_event_library LIB_NAME)
             set_target_properties(
                 "${LIB_NAME}_shared" PROPERTIES
                 OUTPUT_NAME "${LIB_NAME}-${EVENT_PACKAGE_RELEASE}.${CURRENT_MINUS_AGE}"
-                INSTALL_NAME_DIR "${CMAKE_INSTALL_PREFIX}/lib"
+                INSTALL_NAME_DIR "lib"
                 LINK_FLAGS "-compatibility_version ${COMPATIBILITY_VERSION} -current_version ${COMPATIBILITY_VERSION}.${EVENT_ABI_LIBVERSION_REVISION}")
         else()
             math(EXPR CURRENT_MINUS_AGE "${EVENT_ABI_LIBVERSION_CURRENT}-${EVENT_ABI_LIBVERSION_AGE}")