[build] Autodetect Qt{4,5}

.travis.yml

@@ -166,7 +166,7 @@ matrix:
       dist: trusty
       language: cpp
       compiler: "qt4-gcc5-release"
-      env: BUILDTYPE=Release _CXX=g++-5 _CC=gcc-5 WITH_QT_4=1
+      env: BUILDTYPE=Release _CXX=g++-5 _CC=gcc-5
       addons: *qt4
       before_script:
         - mapbox_start_xvfb

Makefile

@@ -361,20 +361,23 @@ endif
 
 #### Qt targets #####################################################
 
-ifeq ($(WITH_QT_4), 1)
-QT_ROOT_PATH = build/qt4-$(BUILD_PLATFORM)-$(BUILD_PLATFORM_VERSION)
-else
-QT_ROOT_PATH = build/qt-$(BUILD_PLATFORM)-$(BUILD_PLATFORM_VERSION)
-endif
-
-ifneq (,$(shell which qmake))
-export QT_INSTALL_DOCS = $(shell qmake -query QT_INSTALL_DOCS)
+QT_QMAKE_FOUND := $(shell command -v qmake 2> /dev/null)
+ifdef QT_QMAKE_FOUND
+  export QT_INSTALL_DOCS = $(shell qmake -query QT_INSTALL_DOCS)
+  ifeq ($(shell qmake -query QT_VERSION | head -c1), 4)
+    QT_ROOT_PATH = build/qt4-$(BUILD_PLATFORM)-$(BUILD_PLATFORM_VERSION)
+    WITH_QT_4=1
+  else
+    QT_ROOT_PATH = build/qt-$(BUILD_PLATFORM)-$(BUILD_PLATFORM_VERSION)
+    WITH_QT_4=0
+  endif
 endif
 
 export QT_OUTPUT_PATH = $(QT_ROOT_PATH)/$(BUILDTYPE)
 QT_BUILD = $(QT_OUTPUT_PATH)/build.ninja
 
 $(QT_BUILD): $(BUILD_DEPS)
+	@scripts/check-qt.sh
 	mkdir -p $(QT_OUTPUT_PATH)
 	(cd $(QT_OUTPUT_PATH) && cmake -G Ninja ../../.. \
 		-DCMAKE_BUILD_TYPE=$(BUILDTYPE) \
@@ -392,6 +395,7 @@ ifeq ($(HOST_PLATFORM), macos)
 
 MACOS_QT_PROJ_PATH = $(QT_ROOT_PATH)/xcode/mbgl.xcodeproj
 $(MACOS_QT_PROJ_PATH): $(BUILD_DEPS)
+	@scripts/check-qt.sh
 	mkdir -p $(QT_ROOT_PATH)/xcode
 	(cd $(QT_ROOT_PATH)/xcode && cmake -G Xcode ../../.. \
 		-DMBGL_PLATFORM=qt \

platform/qt/bitrise-qt4.yml

@@ -19,7 +19,6 @@ workflows:
             brew link qt
             brew linkapps qt
             export BUILDTYPE=Debug
-            export WITH_QT_4=1
             make qt-app
             make run-qt-test
         - is_debug: 'yes'

scripts/check-qt.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+set -e
+set -o pipefail
+
+if [ ! $(command -v qmake 2> /dev/null) ]; then
+    echo "No qmake found - missing Qt development files"
+    exit 1
+fi