Merge remote-tracking branch 'origin/5.11' into 5.12

 Conflicts:
	mkspecs/common/macx.conf

Change-Id: I8576493b417912fa5e5501bc2c1b935d186ac209

3 files changed, 51 insertions, 0 deletions

diff --git a/mkspecs/common/macx.conf b/mkspecs/common/macx.conf
index 8122a54d9d..6e95112f9b 100644
--- a/mkspecs/common/macx.conf
+++ b/mkspecs/common/macx.conf
@@ -7,6 +7,7 @@ QMAKE_MAC_SDK           = macosx
 
 QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.12
 QMAKE_APPLE_DEVICE_ARCHS = x86_64
+QT_MAC_SDK_VERSION_TESTED_WITH = 10.13
 
 device.sdk = macosx
 device.target = device
diff --git a/mkspecs/features/mac/default_post.prf b/mkspecs/features/mac/default_post.prf
index c6eb7c5a2c..353fda41e6 100644
--- a/mkspecs/features/mac/default_post.prf
+++ b/mkspecs/features/mac/default_post.prf
@@ -1,5 +1,43 @@
 load(default_post)
 
+contains(TEMPLATE, .*app) {
+    !macx-xcode {
+        # Detect changes to the platform SDK
+        QMAKE_EXTRA_VARIABLES += QMAKE_MAC_SDK QMAKE_MAC_SDK_VERSION
+        QMAKE_EXTRA_INCLUDES += $$shell_quote($$PWD/sdk.mk)
+    }
+
+    # Detect incompatible SDK versions
+
+    !versionAtLeast(QMAKE_MAC_SDK_VERSION, $$QT_MAC_SDK_VERSION): \
+        warning("Qt requires at least version $$QT_MAC_SDK_VERSION of the platform SDK," \
+              "you're using $${QMAKE_MAC_SDK_VERSION}. Please upgrade.")
+
+    !isEmpty(QT_MAC_SDK_VERSION_TESTED_WITH) {
+        # For Qt developers only
+        !isEmpty($$list($$(QT_MAC_SDK_NO_VERSION_CHECK))): \
+            CONFIG += sdk_no_version_check
+
+        !sdk_no_version_check:!versionAtMost(QMAKE_MAC_SDK_VERSION, $$QT_MAC_SDK_VERSION_TESTED_WITH) {
+            warning("Qt has only been tested with version $$QT_MAC_SDK_VERSION_TESTED_WITH"\
+                    "of the platform SDK, you're using $${QMAKE_MAC_SDK_VERSION}.")
+            warning("This is an unsupported configuration. You may experience build issues," \
+                    "and by using")
+            warning("the $$QMAKE_MAC_SDK_VERSION SDK you are opting in to new features" \
+                    "that Qt has not been prepared for.")
+
+            isEqual(QMAKE_MAC_SDK_VERSION, 10.14): \
+                warning("E.g., 10.14 enables dark mode and layer-backed views," \
+                        "which Qt $${QT_MAJOR_VERSION}.$${QT_MINOR_VERSION} does not support.")
+
+            warning("Please downgrade the SDK you use to build your app to version" \
+                    "$$QT_MAC_SDK_VERSION_TESTED_WITH, or configure")
+            warning("with CONFIG+=sdk_no_version_check when running qmake" \
+                    "to silence this warning.")
+        }
+    }
+}
+
 !no_objective_c:CONFIG += objective_c
 
 qt {
diff --git a/mkspecs/features/mac/sdk.mk b/mkspecs/features/mac/sdk.mk
new file mode 100644
index 0000000000..a7c8268da5
--- /dev/null
+++ b/mkspecs/features/mac/sdk.mk
@@ -0,0 +1,12 @@
+CURRENT_MAC_SDK_VERSION := $(shell /usr/bin/xcrun --sdk $(EXPORT_QMAKE_MAC_SDK) -show-sdk-version)
+
+ifneq ($(CURRENT_MAC_SDK_VERSION),$(EXPORT_QMAKE_MAC_SDK_VERSION))
+    $(info The platform SDK has been changed from version $(EXPORT_QMAKE_MAC_SDK_VERSION) to version $(CURRENT_MAC_SDK_VERSION).)
+    $(info This requires a fresh build. Please wipe the build directory completely,)
+    $(info including any .qmake.stash and .qmake.cache files generated by qmake.)
+    # FIXME: Ideally this should be advertised as just running make distclean, or we
+    # should even do it automatically by having proper makefile dependencies between
+    # .qmake.stash and the SDK version, but as qmake doesn't seem to be consistent in
+    # how it deals with .qmake.stash as a dependency we need to defer that until later.
+    $(error ^)
+endif