[core] Fix MapSnapshotter build failure on Windows

MSVC implementation of std::promise is buggy and only works with types
that can be default-constructed. To avoid a compilation failure in the
instantiation of ask() inside MapSnapshotter::getRegion(), which creates
a std::promise<LanLngBounds>, make LatLngBounds' default constructor
public.

include/mbgl/util/geo.hpp

@@ -105,14 +105,12 @@ class LatLngBounds {
         return bounds;
     }
 
-    /// Returns an infinite bound, a bound for which the constrain method returns its
+    /// Construct an infinite bound, a bound for which the constrain method returns its
     /// input unmodified.
     ///
     /// Note: this is different than LatLngBounds::world() since arbitrary unwrapped
     /// coordinates are also inside the bounds.
-    static LatLngBounds unbounded() {
-        return {};
-    }
+    LatLngBounds() : sw({-90, -180}), ne({90, 180}), bounded(false) {}
 
     // Constructs a LatLngBounds object with the tile's exact boundaries.
     LatLngBounds(const CanonicalTileID&);
@@ -172,9 +170,6 @@ class LatLngBounds {
 
     LatLngBounds(LatLng sw_, LatLng ne_) : sw(sw_), ne(ne_) {}
 
-    LatLngBounds()
-        : sw({-90, -180}), ne({90, 180}), bounded(false) {}
-
     bool containsLatitude(double latitude) const;
     bool containsLongitude(double longitude, LatLng::WrapMode wrap) const;
 

platform/android/src/native_map_view.cpp

@@ -314,7 +314,7 @@ void NativeMapView::setLatLngBounds(jni::JNIEnv& env, const jni::Object<mbgl::an
     if (jBounds) {
         bounds.withLatLngBounds(mbgl::android::LatLngBounds::getLatLngBounds(env, jBounds));
     } else {
-        bounds.withLatLngBounds(mbgl::LatLngBounds::unbounded());
+        bounds.withLatLngBounds(mbgl::LatLngBounds());
     }
     map->setBounds(bounds);
 }

platform/glfw/glfw_view.cpp

@@ -288,11 +288,10 @@ void GLFWView::onKey(GLFWwindow *window, int key, int /*scancode*/, int action,
             break;
         case GLFW_KEY_D: {
             static const std::vector<mbgl::LatLngBounds> bounds = {
-                mbgl::LatLngBounds::hull(mbgl::LatLng { -45.0, -170.0 }, mbgl::LatLng { 45.0, 170.0 }),  // inside
-                mbgl::LatLngBounds::hull(mbgl::LatLng { -45.0, -200.0 }, mbgl::LatLng { 45.0, -160.0 }), // left IDL
-                mbgl::LatLngBounds::hull(mbgl::LatLng { -45.0, 160.0 }, mbgl::LatLng { 45.0, 200.0 }),   // right IDL
-                mbgl::LatLngBounds::unbounded()
-            };
+                mbgl::LatLngBounds::hull(mbgl::LatLng{-45.0, -170.0}, mbgl::LatLng{45.0, 170.0}),  // inside
+                mbgl::LatLngBounds::hull(mbgl::LatLng{-45.0, -200.0}, mbgl::LatLng{45.0, -160.0}), // left IDL
+                mbgl::LatLngBounds::hull(mbgl::LatLng{-45.0, 160.0}, mbgl::LatLng{45.0, 200.0}),   // right IDL
+                mbgl::LatLngBounds()};
             static size_t nextBound = 0u;
             static mbgl::AnnotationID boundAnnotationID = std::numeric_limits<mbgl::AnnotationID>::max();
 
@@ -301,7 +300,7 @@ void GLFWView::onKey(GLFWwindow *window, int key, int /*scancode*/, int action,
 
             view->map->setBounds(mbgl::BoundOptions().withLatLngBounds(bound));
 
-            if (bound == mbgl::LatLngBounds::unbounded()) {
+            if (bound == mbgl::LatLngBounds()) {
                 view->map->removeAnnotation(boundAnnotationID);
                 boundAnnotationID = std::numeric_limits<mbgl::AnnotationID>::max();
             } else {

src/mbgl/map/transform.cpp

@@ -83,14 +83,14 @@ void Transform::jumpTo(const CameraOptions& camera) {
  */
 void Transform::easeTo(const CameraOptions& camera, const AnimationOptions& animation) {
     Duration duration = animation.duration.value_or(Duration::zero());
-    if (state.bounds == LatLngBounds::unbounded() && !isGestureInProgress() && duration != Duration::zero()) {
+    if (state.bounds == LatLngBounds() && !isGestureInProgress() && duration != Duration::zero()) {
         // reuse flyTo, without exaggerated animation, to achieve constant ground speed.
         return flyTo(camera, animation, true);
     }
     const EdgeInsets& padding = camera.padding.value_or(state.edgeInsets);
     LatLng startLatLng = getLatLng(LatLng::Unwrapped);
     const LatLng& unwrappedLatLng = camera.center.value_or(startLatLng);
-    const LatLng& latLng = state.bounds != LatLngBounds::unbounded() ? unwrappedLatLng : unwrappedLatLng.wrapped();
+    const LatLng& latLng = state.bounds != LatLngBounds() ? unwrappedLatLng : unwrappedLatLng.wrapped();
     double zoom = camera.zoom.value_or(getZoom());
     double bearing = camera.bearing ? -*camera.bearing * util::DEG2RAD : getBearing();
     double pitch = camera.pitch ? *camera.pitch * util::DEG2RAD : getPitch();
@@ -102,7 +102,7 @@ void Transform::easeTo(const CameraOptions& camera, const AnimationOptions& anim
         return;
     }
 
-    if (state.bounds == LatLngBounds::unbounded()) {
+    if (state.bounds == LatLngBounds()) {
         if (isGestureInProgress()) {
             // If gesture in progress, we transfer the wrap rounds from the end longitude into
             // start, so the "scroll effect" of rounding the world is the same while assuring the

src/mbgl/map/transform_state.cpp

@@ -10,11 +10,7 @@
 namespace mbgl {
 
 TransformState::TransformState(ConstrainMode constrainMode_, ViewportMode viewportMode_)
-    : bounds(LatLngBounds::unbounded())
-    , constrainMode(constrainMode_)
-    , viewportMode(viewportMode_)
-{
-}
+    : bounds(LatLngBounds()), constrainMode(constrainMode_), viewportMode(viewportMode_) {}
 
 #pragma mark - Matrix
 

test/map/map.test.cpp

@@ -316,7 +316,7 @@ TEST(Map, DefaultBoundOptions) {
 
     EXPECT_EQ(*bounds.minZoom, util::MIN_ZOOM);
     EXPECT_EQ(*bounds.maxZoom, util::DEFAULT_MAX_ZOOM);
-    EXPECT_EQ(*bounds.bounds, LatLngBounds::unbounded());
+    EXPECT_EQ(*bounds.bounds, LatLngBounds());
 }
 
 TEST(Map, MapOptions) {
@@ -1053,4 +1053,4 @@ TEST(Map, NoHangOnMissingImage) {
     test.map.jumpTo(test.map.getStyle().getDefaultCamera());
     // The test passes if the following call does not hang.
     test.frontend.render(test.map);
-}
+}

test/map/transform.test.cpp

@@ -609,15 +609,15 @@ TEST(Transform, LatLngBounds) {
     transform.jumpTo(CameraOptions().withCenter(LatLng()).withZoom(transform.getState().getMaxZoom()));
 
     // Default bounds.
-    ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds::unbounded());
+    ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds());
     ASSERT_EQ(transform.getLatLng(), nullIsland);
 
     // Invalid bounds.
     try {
         transform.setLatLngBounds(LatLngBounds::empty());
         ASSERT_TRUE(false) << "Should throw";
     } catch (...) {
-        ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds::unbounded());
+        ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds());
     }
 
     transform.jumpTo(CameraOptions().withCenter(sanFrancisco));