Don't write local subroutines

run.sh

@@ -1,7 +1,7 @@
 FONT="fonts/NotoSansCJKsc-Regular.otf"
-GIDS="9987"
+GIDS="0,1,2698,3950,4059,8509,14538,38945"
 
-fonttools subset $FONT --drop-tables=GSUB,GPOS,GDEF,FFTM,vhea,vmtx,DSIG,VORG,hdmx \
+fonttools subset $FONT --drop-tables=GSUB,GPOS,GDEF,FFTM,vhea,vmtx,DSIG,VORG,hdmx,cmap \
  --gids=$GIDS --glyph-names --desubroutinize --output-file=out_ft.otf \
  --notdef-outline --no-prune-unicode-ranges --no-prune-codepage-ranges &&
 fonttools ttx -f -o out_ft.xml out_ft.otf &&

src/cff/dict/private_dict.rs

@@ -58,12 +58,7 @@ pub fn write_private_dicts(
             while let Some(operator) = dict_parser.parse_next() {
                 match operator {
                     SUBRS => {
-                        let mut w = Writer::new();
-                        let offset = font_write_context.lsubrs_offsets.as_i32()
-                            - private_dict_offset as i32;
-                        w.write(IntegerNumber::from_i32_as_int5(offset).as_bytes());
-
-                        write(&w.finish(), SUBRS.as_bytes());
+                        // We don't have any subroutines
                     }
                     _ => {
                         dict_parser.parse_operands().unwrap();

src/cff/mod.rs

@@ -94,13 +94,13 @@ pub fn subset<'a>(ctx: &mut Context<'a>) -> Result<()> {
         SubroutineCollection::new(subroutines)
     };
 
-    let mut fd_remapper = FontDictRemapper::new();
+    let mut used_fds = BTreeSet::new();
     let sid_remapper = get_sid_remapper(&table);
     let mut char_strings = vec![];
 
     for old_gid in ctx.mapper.old_gids() {
         let fd_index = table.cid_metadata.fd_select.font_dict_index(old_gid).unwrap();
-        fd_remapper.remap(fd_index);
+        used_fds.insert(fd_index);
 
         let mut decompiler = Decompiler::new(
             gsubrs.get_handler(),
@@ -110,6 +110,12 @@ pub fn subset<'a>(ctx: &mut Context<'a>) -> Result<()> {
         char_strings.push(decompiler.decompile(charstring)?);
     }
 
+    let mut fd_remapper = FontDictRemapper::new();
+
+    for fd in used_fds {
+        fd_remapper.remap(fd);
+    }
+
     let mut font_write_context = FontWriteContext::new(fd_remapper.len());
     let mut subsetted_font = vec![];
 
@@ -134,7 +140,7 @@ pub fn subset<'a>(ctx: &mut Context<'a>) -> Result<()> {
         w.extend(&write_sids(&sid_remapper, table.strings).unwrap());
         // Global Subr INDEX
         // Note: We desubroutinized, so no global subroutines and thus empty index.
-        w.extend(&create_index(vec![vec![]]).unwrap());
+        w.extend(&create_index(vec![]).unwrap());
 
         font_write_context.charset_offset =
             IntegerNumber::from_i32_as_int5(w.len() as i32);
@@ -176,7 +182,7 @@ pub fn subset<'a>(ctx: &mut Context<'a>) -> Result<()> {
         // Again, always empty since we desubroutinize.
         font_write_context.lsubrs_offsets =
             IntegerNumber::from_i32_as_int5(w.len() as i32);
-        w.extend(&create_index(vec![vec![]])?);
+        w.extend(&create_index(vec![])?);
 
         subsetted_font = w.finish();
     }