Revert "Remove unneeded buffer clear_output / remove_output calls"

This reverts commit 2d1ed74.

harfbuzz/harfbuzz@93e6a9b

src/buffer.rs

@@ -789,6 +789,14 @@ impl Buffer {
         self.idx = 0;
     }
 
+    pub fn remove_output(&mut self) {
+        self.have_output = false;
+        self.have_positions = false;
+
+        self.out_len = 0;
+        self.have_separate_output = false;
+    }
+
     pub fn clear_output(&mut self) {
         self.have_output = true;
         self.have_positions = false;

src/ot/layout.rs

@@ -209,6 +209,7 @@ pub fn apply_layout_table<T: LayoutTable>(
         }
 
         if let Some(func) = stage.pause_func {
+            ctx.buffer.clear_output();
             func(plan, face, ctx.buffer);
         }
     }
@@ -223,10 +224,9 @@ fn apply_string<T: LayoutTable>(ctx: &mut ApplyContext, lookup: &T::Lookup) {
 
     if !lookup.is_reverse() {
         // in/out forward substitution/positioning
-        if !T::IN_PLACE {
+        if T::INDEX == TableIndex::GSUB {
             ctx.buffer.clear_output();
         }
-
         ctx.buffer.idx = 0;
 
         if apply_forward(ctx, lookup) {
@@ -238,6 +238,10 @@ fn apply_string<T: LayoutTable>(ctx: &mut ApplyContext, lookup: &T::Lookup) {
         }
     } else {
         // in-place backward substitution/positioning
+        if T::INDEX == TableIndex::GSUB {
+            ctx.buffer.remove_output();
+        }
+
         ctx.buffer.idx = ctx.buffer.len - 1;
         apply_backward(ctx, lookup);
     }

src/shape.rs

@@ -63,6 +63,8 @@ fn shape_internal(ctx: &mut ShapeContext) {
         }
     }
 
+    ctx.buffer.clear_output();
+
     initialize_masks(ctx);
     set_unicode_props(ctx.buffer);
     insert_dotted_circle(ctx.buffer, ctx.face);