Fix non-prefix builds for non qtbase repos

QT_WILL_INSTALL was previously always set to ON when doing a
qtdeclarative build, because
CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT evaluated to false due to
always having to set CMAKE_INSTALL_PREFIX to point to the qtbase build
directory.

Instead of recomputing the value of QT_WILL_INSTALL, compute it once
while configuring qtbase, and add it to the generated
QtBuildInternalsExtra.cmake file, so it propagates to all other repos
that will be built.

Change-Id: If8bf63e7501b5758fe7aa0f799cb0746704f4811
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 21 insertions, 9 deletions

diff --git a/cmake/QtBuildInternalsExtra.cmake.in b/cmake/QtBuildInternalsExtra.cmake.in
index 028cfe2717..6f070ed043 100644
--- a/cmake/QtBuildInternalsExtra.cmake.in
+++ b/cmake/QtBuildInternalsExtra.cmake.in
@@ -15,3 +15,7 @@ set(CMAKE_INSTALL_PREFIX @CMAKE_INSTALL_PREFIX@ CACHE PATH
 if(@FEATURE_developer_build@)
     set(FEATURE_developer_build ON CACHE BOOL "Developer build." FORCE)
 endif()
+
+# Propagate non-prefix builds.
+set(QT_WILL_INSTALL @QT_WILL_INSTALL@ CACHE BOOL
+    "Boolean indicating if doing a Qt prefix build (vs non-prefix build)." FORCE)
diff --git a/cmake/QtSetup.cmake b/cmake/QtSetup.cmake
index fcc26c844a..9fac9875c5 100644
--- a/cmake/QtSetup.cmake
+++ b/cmake/QtSetup.cmake
@@ -42,19 +42,25 @@ set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
 
 # Detect non-prefix builds, either when the install prefix is set to the binary dir
 # or when enabling developer builds and no prefix is specified.
-if((CMAKE_INSTALL_PREFIX STREQUAL CMAKE_BINARY_DIR) OR (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT AND FEATURE_developer_build))
-    set(QT_WILL_INSTALL OFF)
-    # Handle non-prefix builds by setting the cmake install prefix to the project binary dir.
-    if(PROJECT_NAME STREQUAL "QtBase")
+# This detection only happens when building qtbase, and later is propagated via the generated
+# QtBuildInternalsExtra.cmake file.
+if (PROJECT_NAME STREQUAL "QtBase")
+    if((CMAKE_INSTALL_PREFIX STREQUAL CMAKE_BINARY_DIR) OR
+        (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT AND FEATURE_developer_build))
+
+        set(__qt_will_install_value OFF)
+        # Handle non-prefix builds by setting the CMake install prefix to point to qtbase's build
+        # dir.
+        # While building another repo (like qtsvg), the CMAKE_INSTALL_PREFIX or CMAKE_PREFIX_PATH
+        # (either work) should be set on the command line to point to the qtbase build dir.
         set(CMAKE_INSTALL_PREFIX ${CMAKE_BINARY_DIR} CACHE PATH
             "Install path prefix, prepended onto install directories." FORCE)
     else()
-        # No-op. While building another module, the CMAKE_INSTALL_PREFIX or CMAKE_PREFIX_PATH
-        # (either work) should be set on the command line to point to the qtbase build dir.
+        set(__qt_will_install_value ON)
     endif()
-else()
-    set(QT_WILL_INSTALL ON)
-    set(QT_BUILD_TESTING OFF)
+    set(QT_WILL_INSTALL ${__qt_will_install_value} CACHE BOOL
+        "Boolean indicating if doing a Qt prefix build (vs non-prefix build)." FORCE)
+    unset(__qt_will_install_value)
 endif()
 
 if(FEATURE_developer_build)
@@ -64,6 +70,8 @@ if(FEATURE_developer_build)
         set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
     endif()
     set(QT_BUILD_TESTING ON)
+else()
+    set(QT_BUILD_TESTING OFF)
 endif()
 
 ## Set up testing