From a907d7df3488764b74afd219e1ddd368062529d6 Mon Sep 17 00:00:00 2001
From: Alexandru Croitor <alexandru.croitor@qt.io>
Date: Fri, 3 May 2019 15:21:30 +0200
Subject: Handle generating find_dependency() calls for nolink targets

Previously we just recorded that Gui has to link against
Vulkan::Vulkan_nolink, but if an application consumed Gui, it wouldn't
find that target.

We need to record that if a module links against Vulkan_nolink, and
then generate a find_dependency(Vulkan) call in the module config
file.

We also have to assign the _nolink interface library to an export
(the Qt5 one), so that it gets installed as a target.

Change-Id: Icbc29ff4161ab18fdd162196ae128e29c1ee8c80
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
---
 cmake/QtBuild.cmake       | 20 ++++++++++++++++----
 cmake/QtPostProcess.cmake |  8 ++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

(limited to 'cmake')

diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index 1a15c146c7..7c776fcda7 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -193,7 +193,7 @@ macro(assert)
 endmacro()
 
 
-function(qt_create_nolink_target target)
+function(qt_create_nolink_target target export_target)
     if(NOT TARGET "${target}")
         message(FATAL_ERROR "${target} does not exist when trying to build a nolink target.")
     endif()
@@ -205,9 +205,18 @@ function(qt_create_nolink_target target)
         message(FATAL_ERROR "${target} must not be an object library.")
     endif()
 
-    set(nolink_target "${target}_nolink")
+    # Strip off the namespace prefix, so from Vulkan::Vulkan to Vulkan, and then append _nolink.
+    string(REGEX REPLACE "^.*::" "" non_prefixed_target ${target})
+    set(nolink_target "${non_prefixed_target}_nolink")
+
+    # Create the nolink interface target, assign the properties from the original target,
+    # associate the nolink target with the same export which contains
+    # the target that uses the _nolink target.
+    # Also create a namespaced alias of the form {$target}::${target}_nolink which is used by
+    # our modules.
     if(NOT TARGET "${nolink_target}")
-        add_library("${nolink_target}" INTERFACE IMPORTED)
+        add_library("${nolink_target}" INTERFACE)
+        set(prefixed_nolink_target "${target}_nolink")
         set_target_properties("${nolink_target}" PROPERTIES
                               INTERFACE_INCLUDE_DIRECTORIES
                               $<TARGET_PROPERTY:${target},INTERFACE_INCLUDE_DIRECTORIES>
@@ -219,6 +228,8 @@ function(qt_create_nolink_target target)
                               $<TARGET_PROPERTY:${target},INTERFACE_COMPILE_OPTIONS>
                               INTERFACE_COMPILE_FEATURES
                               $<TARGET_PROPERTY:${target},INTERFACE_COMPILE_FEATURES>)
+        install(TARGETS ${nolink_target} EXPORT ${export_target})
+        add_library(${prefixed_nolink_target} ALIAS ${nolink_target})
     endif()
 endfunction()
 
@@ -435,7 +446,8 @@ function(extend_target target)
         foreach(lib ${arg_PUBLIC_LIBRARIES} ${arg_LIBRARIES})
             string(REGEX REPLACE "_nolink$" "" base_lib "${lib}")
             if(NOT base_lib STREQUAL lib)
-                qt_create_nolink_target("${base_lib}")
+                set(export_target "${INSTALL_CMAKE_NAMESPACE}${target}Targets")
+                qt_create_nolink_target("${base_lib}" ${export_target})
             endif()
         endforeach()
 
diff --git a/cmake/QtPostProcess.cmake b/cmake/QtPostProcess.cmake
index 57d194c037..fe6d70985b 100644
--- a/cmake/QtPostProcess.cmake
+++ b/cmake/QtPostProcess.cmake
@@ -58,6 +58,14 @@ function(qt_internal_create_depends_files)
 
         foreach(dep ${${depends_var}})
             # Gather third party packages that should be found when using the Qt module.
+            # Also handle nolink target dependencies.
+            string(REGEX REPLACE "_nolink$" "" base_dep "${dep}")
+            if(NOT base_dep STREQUAL dep)
+                # Resets target name like Vulkan_nolink to Vulkan, because we need to call
+                # find_package(Vulkan).
+                set(dep ${base_dep})
+            endif()
+
             if(TARGET ${dep})
                 list(FIND third_party_deps_seen ${dep} dep_seen)
 
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