From 93df3de1f30b6f65b025b33e9cd73ad479295e59 Mon Sep 17 00:00:00 2001
From: Alexandru Croitor <alexandru.croitor@qt.io>
Date: Mon, 7 Oct 2024 16:11:52 +0200
Subject: [PATCH] CMake: Improve pri library handling for genexes and friends

After 4dce218ac400afcb54aa2a85a0b27947fec583cb got merged, we started
considering the INTERFACE_LINK_LIBRARIES property of UNKNOWN_LIBRARY
targets in addition to INTERFACE_LIBRARY targets, when collecting
dependencies for pri file generation.

These can contain genexes like $<LINK_ONLY:...> or
$<TARGET_OBJECTS:...>, which are not supported by file(GENERATE),
or special directory scope tokens like ::@, which are not valid
targets or library names.

One such case was in the downstream vcpkg build of Qt which adds
`$<LINK_ONLY:EXPAT::EXPAT>` to the INTERFACE_LINK_LIBRARIES of the
Fontconfig::Fontconfig target.

We strip or handle these cases for prl file generation as part of
calling __qt_internal_walk_libs.

Change the pri generation to handle them in a similar manner by copying
over the same logic.

Amends 4dce218ac400afcb54aa2a85a0b27947fec583cb

Pick-to: 6.8
Fixes: QTBUG-129471
Change-Id: Id4a574ee2411f6d64179c419f352168fde1914d3
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
---
 cmake/QtPriHelpers.cmake | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/cmake/QtPriHelpers.cmake b/cmake/QtPriHelpers.cmake
index 3b9d205c36d..7b023af6e3c 100644
--- a/cmake/QtPriHelpers.cmake
+++ b/cmake/QtPriHelpers.cmake
@@ -57,10 +57,34 @@ function(qt_generate_qmake_libraries_pri_content module_name output_root_dir out
                 list(APPEND lib_incdir "${target_include_dir}")
                 list(APPEND lib_defines "$<TARGET_PROPERTY:${lib_target},INTERFACE_COMPILE_DEFINITIONS>")
             else()
-                if(lib_target MATCHES "/([^/]+).framework$")
+                # Strip any directory scope tokens.
+                __qt_internal_strip_target_directory_scope_token("${lib_target}" lib_target)
+
+                # Skip CMAKE_DIRECTORY_ID_SEP. If a target_link_libraries is applied to a target
+                # that was defined in a different scope, CMake appends and prepends a special
+                # directory id separator. Filter those out.
+                if(lib_target MATCHES "^::@")
+                    continue()
+
+                elseif(lib_target MATCHES "^\\$<TARGET_OBJECTS:")
+                    # Skip object files.
+                    continue()
+
+                elseif(lib_target MATCHES "/([^/]+).framework$")
+                    # Handle frameworks
                     list(APPEND lib_libs "-framework ${CMAKE_MATCH_1}")
+
+                elseif(lib_target MATCHES "^\\$<LINK_ONLY:(.*)>$")
+                    # Extract value of LINK_ONLY genex, because it can't be used in file(GENERATE)
+                    set(lib_target "${CMAKE_MATCH_1}")
+                    if(lib_target)
+                        list(PREPEND lib_targets ${lib_target})
+                    endif()
                 else()
-                    list(APPEND lib_libs "${lib_target}")
+                    # Regular library name, library path, or -lfoo-like flag. Check for emptiness.
+                    if(lib_target)
+                        list(APPEND lib_libs "${lib_target}")
+                    endif()
                 endif()
             endif()
         endwhile()