wasm: Custom Debug impl for NameSection

compiler/gen_wasm/src/wasm_module/mod.rs

@@ -119,6 +119,7 @@ impl<'a> WasmModule<'a> {
             + self.element.size()
             + self.code.size()
             + self.data.size()
+            + self.names.size()
     }
 
     pub fn preload(arena: &'a Bump, bytes: &[u8]) -> Self {
@@ -146,7 +147,6 @@ impl<'a> WasmModule<'a> {
         let global = GlobalSection::preload(arena, bytes, &mut cursor);
 
         ExportSection::skip_bytes(bytes, &mut cursor);
-
         let export = ExportSection::empty(arena);
 
         let start = OpaqueSection::preload(SectionId::Start, arena, bytes, &mut cursor);

compiler/gen_wasm/src/wasm_module/sections.rs

@@ -1,3 +1,5 @@
+use std::fmt::Debug;
+
 use bumpalo::collections::vec::Vec;
 use bumpalo::Bump;
 use roc_collections::all::MutMap;
@@ -1153,7 +1155,6 @@ enum NameSubSections {
     LocalNames = 2,
 }
 
-#[derive(Debug)]
 pub struct NameSection<'a> {
     pub bytes: Vec<'a, u8>,
     pub functions: MutMap<&'a [u8], u32>,
@@ -1189,6 +1190,10 @@ impl<'a> NameSection<'a> {
         section
     }
 
+    pub fn size(&self) -> usize {
+        self.bytes.len()
+    }
+
     fn parse_body(
         &mut self,
         arena: &'a Bump,
@@ -1253,6 +1258,27 @@ impl<'a> Serialize for NameSection<'a> {
     }
 }
 
+impl<'a> Debug for NameSection<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "NameSection\n")?;
+
+        // We want to display index->name because it matches the binary format and looks nicer.
+        // But our hashmap is name->index because that's what code gen wants to look up.
+        let mut by_index = std::vec::Vec::with_capacity(self.functions.len());
+        for (name, index) in self.functions.iter() {
+            by_index.push((*index, name));
+        }
+        by_index.sort_unstable();
+
+        for (index, name) in by_index.iter() {
+            let name_str = unsafe { std::str::from_utf8_unchecked(name) };
+            write!(f, "  {:4}: {}\n", index, name_str)?;
+        }
+
+        Ok(())
+    }
+}
+
 /*******************************************************************
  *
  * Unit tests