Fix compilation errors with libc++ on QNX 7

This patch fixes the compilation errors on QNX 7:
1) QNX 7 compiler (i.e qcc based GCC 5.4.0 with libc++ from LLVM) has a
limited c++11 feature support and causing the compilation
errors with the inheriting constructors. This fixes the issues by
providing the required constructors explicitly.

2) Resolves an ambiguous overload error with optional<T>

6 files changed, 28 insertions, 25 deletions

diff --git a/include/mbgl/style/expression/compound_expression.hpp b/include/mbgl/style/expression/compound_expression.hpp
index 04562752a6..c618f2f206 100644
--- a/include/mbgl/style/expression/compound_expression.hpp
+++ b/include/mbgl/style/expression/compound_expression.hpp
@@ -33,7 +33,10 @@ namespace expression {
 */
 struct VarargsType { type::Type type; };
 template <typename T>
-struct Varargs : std::vector<T> { using std::vector<T>::vector; };
+struct Varargs : std::vector<T> {
+    template <class... Args>
+    Varargs(Args&&... args) : std::vector<T>(std::forward<Args>(args)...) {}
+};
 
 namespace detail {
 // Base class for the Signature<Fn> structs that are used to determine
diff --git a/src/mbgl/style/expression/interpolate.cpp b/src/mbgl/style/expression/interpolate.cpp
index 852042382c..54fbc6e1d7 100644
--- a/src/mbgl/style/expression/interpolate.cpp
+++ b/src/mbgl/style/expression/interpolate.cpp
@@ -170,23 +170,23 @@ ParseResult parseInterpolate(const Convertible& value, ParsingContext& ctx) {
             labelValue->match(
                 [&](uint64_t n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{static_cast<double>(n)};
                     }
                 },
                 [&](int64_t n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{static_cast<double>(n)};
                     }
                 },
                 [&](double n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{n};
                     }
                 },
                 [&](const auto&) {}
diff --git a/src/mbgl/style/expression/match.cpp b/src/mbgl/style/expression/match.cpp
index 340f1dab4d..4b4984811f 100644
--- a/src/mbgl/style/expression/match.cpp
+++ b/src/mbgl/style/expression/match.cpp
@@ -138,7 +138,7 @@ optional<InputType> parseInputValue(const Convertible& input, ParsingContext& pa
                     parentContext.error("Branch labels must be integers no larger than " + util::toString(Value::maxSafeInteger()) + ".", index);
                 } else {
                     type = {type::Number};
-                    result = {static_cast<int64_t>(n)};
+                    result = optional<InputType>{static_cast<int64_t>(n)};
                 }
             },
             [&] (int64_t n) {
@@ -146,7 +146,7 @@ optional<InputType> parseInputValue(const Convertible& input, ParsingContext& pa
                     parentContext.error("Branch labels must be integers no larger than " + util::toString(Value::maxSafeInteger()) + ".", index);
                 } else {
                     type = {type::Number};
-                    result = {n};
+                    result = optional<InputType>{n};
                 }
             },
             [&] (double n) {
@@ -156,7 +156,7 @@ optional<InputType> parseInputValue(const Convertible& input, ParsingContext& pa
                     parentContext.error("Numeric branch labels must be integer values.", index);
                 } else {
                     type = {type::Number};
-                    result = {static_cast<int64_t>(n)};
+                    result = optional<InputType>{static_cast<int64_t>(n)};
                 }
             },
             [&] (const std::string& s) {
diff --git a/src/mbgl/style/expression/step.cpp b/src/mbgl/style/expression/step.cpp
index ee6055091e..a1ca0a702e 100644
--- a/src/mbgl/style/expression/step.cpp
+++ b/src/mbgl/style/expression/step.cpp
@@ -127,23 +127,23 @@ ParseResult Step::parse(const mbgl::style::conversion::Convertible& value, Parsi
             labelValue->match(
                 [&](uint64_t n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{static_cast<double>(n)};
                     }
                 },
                 [&](int64_t n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{static_cast<double>(n)};
                     }
                 },
                 [&](double n) {
                     if (n > std::numeric_limits<double>::max()) {
-                        label = {std::numeric_limits<double>::infinity()};
+                        label = optional<double>{std::numeric_limits<double>::infinity()};
                     } else {
-                        label = {static_cast<double>(n)};
+                        label = optional<double>{n};
                     }
                 },
                 [&](const auto&) {}
diff --git a/src/mbgl/tile/geometry_tile_data.hpp b/src/mbgl/tile/geometry_tile_data.hpp
index 449d8cab28..bd64a1d153 100644
--- a/src/mbgl/tile/geometry_tile_data.hpp
+++ b/src/mbgl/tile/geometry_tile_data.hpp
@@ -22,19 +22,19 @@ class GeometryCoordinates : public std::vector<GeometryCoordinate> {
 public:
     using coordinate_type = int16_t;
 
-    GeometryCoordinates() = default;
-    GeometryCoordinates(const std::vector<GeometryCoordinate>& v)
-        : std::vector<GeometryCoordinate>(v) {}
-    GeometryCoordinates(std::vector<GeometryCoordinate>&& v)
-        : std::vector<GeometryCoordinate>(std::move(v)) {}
-
-    using std::vector<GeometryCoordinate>::vector;
+    template <class... Args>
+    GeometryCoordinates(Args&&... args) : std::vector<GeometryCoordinate>(std::forward<Args>(args)...) {}
+    GeometryCoordinates(std::initializer_list<GeometryCoordinate> args)
+      : std::vector<GeometryCoordinate>(std::move(args)) {}
 };
 
 class GeometryCollection : public std::vector<GeometryCoordinates> {
 public:
     using coordinate_type = int16_t;
-    using std::vector<GeometryCoordinates>::vector;
+    template <class... Args>
+    GeometryCollection(Args&&... args) : std::vector<GeometryCoordinates>(std::forward<Args>(args)...) {}
+    GeometryCollection(std::initializer_list<GeometryCoordinates> args)
+      : std::vector<GeometryCoordinates>(std::move(args)) {}
 };
 
 class GeometryTileFeature {
diff --git a/test/api/recycle_map.cpp b/test/api/recycle_map.cpp
index ca6abac8c1..fc7e5223ec 100644
--- a/test/api/recycle_map.cpp
+++ b/test/api/recycle_map.cpp
@@ -35,7 +35,7 @@ TEST(API, RecycleMapUpdateImages) {
 
     auto loadStyle = [&](auto markerName, auto markerPath) {
         auto source = std::make_unique<GeoJSONSource>("geometry");
-        source->setGeoJSON({ Point<double> { 0, 0 } });
+        source->setGeoJSON( Geometry<double>{ Point<double>{ 0, 0 } } );
 
         auto layer = std::make_unique<SymbolLayer>("geometry", "geometry");
         layer->setIconImage({ markerName });