[codegen] Better handling of computed lengths

This fixes an issue where we were incorrectly truncating the all
computed lengths to be u16s, even if the value would be stored as a u32.

We now keep computed values as usize and then generate a conversion for
the appropriate type only at the callsite, instead of blindly converting
to a u16 earlier on.

font-codegen/src/fields.rs

@@ -1304,7 +1304,7 @@ impl Field {
                     let typ = self.typ.cooked_type_tokens();
                     let expr = inline_expr.compile_expr();
                     if !inline_expr.referenced_fields.is_empty() {
-                        quote!(#expr.unwrap() as #typ)
+                        quote!( #typ :: try_from(#expr).unwrap() )
                     } else {
                         quote!(#expr as #typ)
                     }

write-fonts/generated/generated_avar.rs

@@ -33,7 +33,7 @@ impl FontWrite for Avar {
         let version = self.compute_version() as MajorMinor;
         version.write_into(writer);
         (0 as u16).write_into(writer);
-        (array_len(&self.axis_segment_maps).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.axis_segment_maps)).unwrap()).write_into(writer);
         self.axis_segment_maps.write_into(writer);
         version
             .compatible((2u16, 0u16))
@@ -113,7 +113,7 @@ impl SegmentMaps {
 impl FontWrite for SegmentMaps {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.axis_value_maps).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.axis_value_maps)).unwrap()).write_into(writer);
         self.axis_value_maps.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_base.rs

@@ -164,7 +164,7 @@ impl BaseTagList {
 impl FontWrite for BaseTagList {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.baseline_tags).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.baseline_tags)).unwrap()).write_into(writer);
         self.baseline_tags.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -222,7 +222,7 @@ impl BaseScriptList {
 impl FontWrite for BaseScriptList {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.base_script_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.base_script_records)).unwrap()).write_into(writer);
         self.base_script_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -346,7 +346,7 @@ impl FontWrite for BaseScript {
     fn write_into(&self, writer: &mut TableWriter) {
         self.base_values.write_into(writer);
         self.default_min_max.write_into(writer);
-        (array_len(&self.base_lang_sys_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.base_lang_sys_records)).unwrap()).write_into(writer);
         self.base_lang_sys_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -472,7 +472,7 @@ impl FontWrite for BaseValues {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         self.default_baseline_index.write_into(writer);
-        (array_len(&self.base_coords).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.base_coords)).unwrap()).write_into(writer);
         self.base_coords.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -545,7 +545,7 @@ impl FontWrite for MinMax {
     fn write_into(&self, writer: &mut TableWriter) {
         self.min_coord.write_into(writer);
         self.max_coord.write_into(writer);
-        (array_len(&self.feat_min_max_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.feat_min_max_records)).unwrap()).write_into(writer);
         self.feat_min_max_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_cmap.rs

@@ -27,7 +27,7 @@ impl FontWrite for Cmap {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         (0 as u16).write_into(writer);
-        (array_len(&self.encoding_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.encoding_records)).unwrap()).write_into(writer);
         self.encoding_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -592,7 +592,7 @@ impl FontWrite for Cmap4 {
         (4 as u16).write_into(writer);
         (self.compute_length() as u16).write_into(writer);
         self.language.write_into(writer);
-        (2 * array_len(&self.end_code).unwrap() as u16).write_into(writer);
+        (u16::try_from(2 * array_len(&self.end_code)).unwrap()).write_into(writer);
         (self.compute_search_range() as u16).write_into(writer);
         (self.compute_entry_selector() as u16).write_into(writer);
         (self.compute_range_shift() as u16).write_into(writer);
@@ -963,7 +963,7 @@ impl FontWrite for Cmap12 {
         (0 as u16).write_into(writer);
         (self.compute_length() as u32).write_into(writer);
         self.language.write_into(writer);
-        (array_len(&self.groups).unwrap() as u32).write_into(writer);
+        (u32::try_from(array_len(&self.groups)).unwrap()).write_into(writer);
         self.groups.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_font.rs

@@ -41,7 +41,7 @@ impl FontWrite for TableDirectory {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         self.sfnt_version.write_into(writer);
-        (array_len(&self.table_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.table_records)).unwrap()).write_into(writer);
         self.search_range.write_into(writer);
         self.entry_selector.write_into(writer);
         self.range_shift.write_into(writer);

write-fonts/generated/generated_gdef.rs

@@ -152,7 +152,7 @@ impl FontWrite for AttachList {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         self.coverage.write_into(writer);
-        (array_len(&self.attach_points).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.attach_points)).unwrap()).write_into(writer);
         self.attach_points.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -213,7 +213,7 @@ impl AttachPoint {
 impl FontWrite for AttachPoint {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.point_indices).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.point_indices)).unwrap()).write_into(writer);
         self.point_indices.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -275,7 +275,7 @@ impl FontWrite for LigCaretList {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         self.coverage.write_into(writer);
-        (array_len(&self.lig_glyphs).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.lig_glyphs)).unwrap()).write_into(writer);
         self.lig_glyphs.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -337,7 +337,7 @@ impl LigGlyph {
 impl FontWrite for LigGlyph {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.caret_values).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.caret_values)).unwrap()).write_into(writer);
         self.caret_values.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -650,7 +650,7 @@ impl FontWrite for MarkGlyphSets {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
-        (array_len(&self.coverages).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.coverages)).unwrap()).write_into(writer);
         self.coverages.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_gpos.rs

@@ -581,7 +581,7 @@ impl MarkArray {
 impl FontWrite for MarkArray {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.mark_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.mark_records)).unwrap()).write_into(writer);
         self.mark_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -837,7 +837,7 @@ impl FontWrite for SinglePosFormat2 {
         (2 as u16).write_into(writer);
         self.coverage.write_into(writer);
         (self.compute_value_format() as ValueFormat).write_into(writer);
-        (array_len(&self.value_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.value_records)).unwrap()).write_into(writer);
         self.value_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1002,7 +1002,7 @@ impl FontWrite for PairPosFormat1 {
         self.coverage.write_into(writer);
         (self.compute_value_format1() as ValueFormat).write_into(writer);
         (self.compute_value_format2() as ValueFormat).write_into(writer);
-        (array_len(&self.pair_sets).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.pair_sets)).unwrap()).write_into(writer);
         self.pair_sets.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1063,7 +1063,7 @@ impl PairSet {
 impl FontWrite for PairSet {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.pair_value_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.pair_value_records)).unwrap()).write_into(writer);
         self.pair_value_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1371,7 +1371,7 @@ impl FontWrite for CursivePosFormat1 {
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.entry_exit_record).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.entry_exit_record)).unwrap()).write_into(writer);
         self.entry_exit_record.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1578,7 +1578,7 @@ impl BaseArray {
 impl FontWrite for BaseArray {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.base_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.base_records)).unwrap()).write_into(writer);
         self.base_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1774,7 +1774,7 @@ impl LigatureArray {
 impl FontWrite for LigatureArray {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.ligature_attaches).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.ligature_attaches)).unwrap()).write_into(writer);
         self.ligature_attaches.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1823,7 +1823,7 @@ impl LigatureAttach {
 impl FontWrite for LigatureAttach {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.component_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.component_records)).unwrap()).write_into(writer);
         self.component_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -2018,7 +2018,7 @@ impl Mark2Array {
 impl FontWrite for Mark2Array {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.mark2_records).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.mark2_records)).unwrap()).write_into(writer);
         self.mark2_records.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_gsub.rs

@@ -408,7 +408,7 @@ impl FontWrite for SingleSubstFormat2 {
     fn write_into(&self, writer: &mut TableWriter) {
         (2 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.substitute_glyph_ids).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.substitute_glyph_ids)).unwrap()).write_into(writer);
         self.substitute_glyph_ids.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -477,7 +477,7 @@ impl FontWrite for MultipleSubstFormat1 {
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.sequences).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.sequences)).unwrap()).write_into(writer);
         self.sequences.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -539,7 +539,7 @@ impl Sequence {
 impl FontWrite for Sequence {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.substitute_glyph_ids).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.substitute_glyph_ids)).unwrap()).write_into(writer);
         self.substitute_glyph_ids.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -603,7 +603,7 @@ impl FontWrite for AlternateSubstFormat1 {
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.alternate_sets).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.alternate_sets)).unwrap()).write_into(writer);
         self.alternate_sets.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -671,7 +671,7 @@ impl AlternateSet {
 impl FontWrite for AlternateSet {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.alternate_glyph_ids).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.alternate_glyph_ids)).unwrap()).write_into(writer);
         self.alternate_glyph_ids.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -735,7 +735,7 @@ impl FontWrite for LigatureSubstFormat1 {
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.ligature_sets).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.ligature_sets)).unwrap()).write_into(writer);
         self.ligature_sets.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -798,7 +798,7 @@ impl LigatureSet {
 impl FontWrite for LigatureSet {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
-        (array_len(&self.ligatures).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.ligatures)).unwrap()).write_into(writer);
         self.ligatures.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -860,7 +860,7 @@ impl FontWrite for Ligature {
     #[allow(clippy::unnecessary_cast)]
     fn write_into(&self, writer: &mut TableWriter) {
         self.ligature_glyph.write_into(writer);
-        (plus_one(&self.component_glyph_ids.len()).unwrap() as u16).write_into(writer);
+        (u16::try_from(plus_one(&self.component_glyph_ids.len())).unwrap()).write_into(writer);
         self.component_glyph_ids.write_into(writer);
     }
     fn table_type(&self) -> TableType {
@@ -1120,11 +1120,11 @@ impl FontWrite for ReverseChainSingleSubstFormat1 {
     fn write_into(&self, writer: &mut TableWriter) {
         (1 as u16).write_into(writer);
         self.coverage.write_into(writer);
-        (array_len(&self.backtrack_coverages).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.backtrack_coverages)).unwrap()).write_into(writer);
         self.backtrack_coverages.write_into(writer);
-        (array_len(&self.lookahead_coverages).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.lookahead_coverages)).unwrap()).write_into(writer);
         self.lookahead_coverages.write_into(writer);
-        (array_len(&self.substitute_glyph_ids).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.substitute_glyph_ids)).unwrap()).write_into(writer);
         self.substitute_glyph_ids.write_into(writer);
     }
     fn table_type(&self) -> TableType {

write-fonts/generated/generated_gvar.rs

@@ -26,7 +26,7 @@ impl FontWrite for Gvar {
     fn write_into(&self, writer: &mut TableWriter) {
         (MajorMinor::VERSION_1_0 as MajorMinor).write_into(writer);
         self.axis_count.write_into(writer);
-        (array_len(&self.shared_tuples).unwrap() as u16).write_into(writer);
+        (u16::try_from(array_len(&self.shared_tuples)).unwrap()).write_into(writer);
         self.shared_tuples.write_into(writer);
         (self.compute_glyph_count() as u16).write_into(writer);
         (self.compute_flags() as GvarFlags).write_into(writer);