Update some documentation about longer names (#1667)

Adding some follow-up documentation to #1650

Author: alexcrichton

crates/wasmparser/src/binary_reader.rs

@@ -697,7 +697,9 @@ impl<'a> BinaryReader<'a> {
     }
 
     /// Reads a WebAssembly string from the module.
+    ///
     /// # Errors
+    ///
     /// If `BinaryReader` has less than up to four bytes remaining, the string's
     /// length exceeds the remaining bytes, the string's length exceeds
     /// `limits::MAX_WASM_STRING_SIZE`, or the string contains invalid utf-8.
@@ -713,6 +715,10 @@ impl<'a> BinaryReader<'a> {
     }
 
     /// Reads a unlimited WebAssembly string from the module.
+    ///
+    /// Note that this is similar to [`BinaryReader::read_string`] except that
+    /// it will not limit the size of the returned string by
+    /// `limits::MAX_WASM_STRING_SIZE`.
     pub fn read_unlimited_string(&mut self) -> Result<&'a str> {
         let len = self.read_var_u32()? as usize;
         return self.internal_read_string(len);

crates/wasmparser/src/readers/core/names.rs

@@ -33,6 +33,9 @@ pub struct Naming<'a> {
 impl<'a> FromReader<'a> for Naming<'a> {
     fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
         let index = reader.read_var_u32()?;
+        // This seems to match what browsers do where they don't limit the
+        // length of names in the `name` section while they do limit the names
+        // in the import and export section for example.
         let name = reader.read_unlimited_string()?;
         Ok(Naming { index, name })
     }