[core] Use UTF-16 instead of UTF-32 for label features to avoid extra conversions and reduce in-memory size.

Continue to use uint32 as glyph ID to maintain Glyph PBF, even though we're only using 16 bits of that uint32.
Use std::codecvt instead of boost::unicode_iterator for UTF8->UTF16 conversions.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mbgl/layout/merge_lines.cpp b/src/mbgl/layout/merge_lines.cpp
index f4fdb82617..676cbc092d 100644
--- a/src/mbgl/layout/merge_lines.cpp
+++ b/src/mbgl/layout/merge_lines.cpp
@@ -47,10 +47,10 @@ enum class Side {
 };
 
 size_t
-getKey(const std::u32string& text, const GeometryCollection& geom, Side side) {
+getKey(const std::u16string& text, const GeometryCollection& geom, Side side) {
     const GeometryCoordinate& coord = side == Side::Right ? geom[0].back() : geom[0].front();
 
-    auto hash = std::hash<std::u32string>()(text);
+    auto hash = std::hash<std::u16string>()(text);
     boost::hash_combine(hash, coord.x);
     boost::hash_combine(hash, coord.y);
     return hash;