From 5528bcf99c79d7a2658b3444205e003fb36f1283 Mon Sep 17 00:00:00 2001
From: Alexandru Croitor <alexandru.croitor@qt.io>
Date: Tue, 30 Jul 2019 11:15:32 +0200
Subject: [PATCH] Protect against extending imported host targets

When cross-compiling qtdeclarative, add_qt_tools makes sure to import
the host tool and not build it. But there are also some
extend_target and add_qt_resource calls which try to extend the host
tool.

Make sure to protect those functions not to do anything if they are
called on an imported target.

Change-Id: Ifd8bcab8e56ad389a8c145382b23bd2c1bda5e81
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
---
 cmake/QtBuild.cmake | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index e00da0f17c5..e51013a325b 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -350,6 +350,17 @@ function(qt_set_up_nonprefix_build)
     endif()
 endfunction()
 
+function(qt_is_imported_target target out_var)
+    if(NOT TARGET "${target}")
+        set(target "${QT_CMAKE_EXPORT_NAMESPACE}::${target}")
+    endif()
+    if(NOT TARGET "${target}")
+        message(FATAL_ERROR "Invalid target given to qt_is_imported_target: ${target}")
+    endif()
+    get_target_property(is_imported "${target}" IMPORTED)
+    set(${out_var} "${is_imported}" PARENT_SCOPE)
+endfunction()
+
 # Generates module .pri files for consumption by qmake
 function(qt_generate_module_pri_file target target_path pri_files_var)
     set(flags INTERNAL_MODULE)
@@ -854,6 +865,12 @@ endfunction()
 # This function can be used to add sources/libraries/etc. to the specified CMake target
 # if the provided CONDITION evaluates to true.
 function(extend_target target)
+    # Don't try to extend_target when cross compiling an imported host target (like a tool).
+    qt_is_imported_target("${target}" is_imported)
+    if(is_imported)
+        return()
+    endif()
+
     if (NOT TARGET "${target}")
         message(FATAL_ERROR "Trying to extend non-existing target \"${target}\".")
     endif()
@@ -2322,9 +2339,14 @@ function(qt_create_tracepoints name tracePointsFile)
         "#include <private/qtrace_p.h>")
 endfunction()
 
-
-
 function(add_qt_resource target resourceName)
+    # Don't try to add resources when cross compiling, and the target is actually a host target
+    # (like a tool).
+    qt_is_imported_target("${target}" is_imported)
+    if(is_imported)
+        return()
+    endif()
+
     qt_parse_all_arguments(rcc "add_qt_resource" "" "PREFIX;LANG;BASE" "FILES" ${ARGN})
 
     # Generate .qrc file: