fix(abi): check for uint8 params in human readable types (#789)

* fix(abi): check for uint8 params in human readable types

* Update ethers-core/src/abi/human_readable.rs

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

* fix mapping detection

* rustfmt

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

ethers-core/src/abi/human_readable.rs

@@ -236,6 +236,15 @@ impl AbiParser {
         Ok(EventParam { name: name.to_string(), indexed, kind: self.parse_type(type_str)?.0 })
     }
 
+    /// Returns the parsed function from the input string
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use ethers_core::abi::AbiParser;
+    /// let f = AbiParser::default()
+    ///     .parse_function("bar(uint256 x, uint256 y, address addr)").unwrap();
+    /// ```
     pub fn parse_function(&mut self, s: &str) -> Result<Function> {
         let mut input = s.trim();
         let shorthand = !input.starts_with("function ");
@@ -330,11 +339,55 @@ impl AbiParser {
 
     /// Returns the `ethabi` `ParamType` for the function parameter and the aliased struct type, if
     /// it is a user defined struct
+    ///
+    /// **NOTE**: the  `ethabi` Reader treats unknown identifiers as `UInt(8)`, because solc uses
+    /// the _name_ of a solidity enum for the value of the `type` of the ABI, but only in sol
+    /// libraries. If the enum is defined in a contract the value of the `type` is `uint8`
+    ///
+    /// # Example ABI for an enum in a __contract__
+    /// ```json
+    /// {
+    ///   "internalType": "enum ContractTest.TestEnum",
+    ///   "name": "test",
+    ///   "type": "uint8"
+    /// }
+    /// ```
+    ///
+    /// # Example ABI for an enum in a __library__
+    /// ```json
+    /// {
+    ///   "internalType": "enum ContractTest.TestEnum",
+    ///   "name": "test",
+    ///   "type": "ContractTest.TestEnum"
+    /// }
+    /// ```
+    ///
+    /// See https://github.com/rust-ethereum/ethabi/issues/254
+    ///
+    /// Therefore, we need to double-check if the `ethabi::Reader` parsed an `uint8`, and ignore the
+    /// type if `type_str` is not uint8. However can lead to some problems if a function param is
+    /// array of custom types for example, like `Foo[]`, which the `Reader` would identify as
+    /// `uint8[]`. Therefor if the `Reader` returns an `uint8` we also check that the input string
+    /// contains a `uint8`. This however can still lead to false detection of `uint8` and is only
+    /// solvable with a more sophisticated parser: https://github.com/gakonst/ethers-rs/issues/474
     fn parse_type(&self, type_str: &str) -> Result<(ParamType, Option<String>)> {
         if let Ok(kind) = Reader::read(type_str) {
+            if is_likely_tuple_not_uint8(&kind, type_str) {
+                // if we detected an `ParamType::Uint(8)` but the input string does not include a
+                // `uint8` then it's highly likely that we try parsing a struct instead
+                self.parse_struct_type(type_str)
+            } else {
                 Ok((kind, None))
+            }
         } else {
             // try struct instead
+            self.parse_struct_type(type_str)
+        }
+    }
+
+    /// Attempts to parse the `type_str` as a `struct`, resolving all fields of the struct into a
+    /// `ParamType::Tuple`
+    fn parse_struct_type(&self, type_str: &str) -> Result<(ParamType, Option<String>)> {
         if let Ok(field) = StructFieldType::parse(type_str) {
             let struct_ty = field
                 .as_struct()
@@ -356,7 +409,6 @@ impl AbiParser {
             bail!("Failed determine event type `{}`", type_str)
         }
     }
-    }
 
     pub fn parse_constructor(&self, s: &str) -> Result<Constructor> {
         let inputs = self.constructor_inputs(s)?.into_iter().map(|s| s.0).collect();
@@ -463,6 +515,30 @@ fn detect_state_mutability(s: &str) -> StateMutability {
     }
 }
 
+/// Checks if the input `ParamType` contains a `uint8` that the `type_str` also contains `uint8`
+///
+/// Returns `true` if `kind` contains `uint8` but the type_str doesnt
+///
+/// See `AbiParser::parse_type`
+pub(crate) fn is_likely_tuple_not_uint8(kind: &ParamType, type_str: &str) -> bool {
+    if contains_uint8(kind) {
+        !type_str.contains("uint8")
+    } else {
+        false
+    }
+}
+
+/// Returns true if the `ParamType` contains an `uint8`
+pub fn contains_uint8(kind: &ParamType) -> bool {
+    match kind {
+        ParamType::Uint(8) => true,
+        ParamType::Array(kind) => contains_uint8(&*kind),
+        ParamType::FixedArray(kind, _) => contains_uint8(&*kind),
+        ParamType::Tuple(tuple) => tuple.iter().any(contains_uint8),
+        _ => false,
+    }
+}
+
 pub(crate) fn is_first_ident_char(c: char) -> bool {
     matches!(c, 'a'..='z' | 'A'..='Z' | '_')
 }

ethers-core/src/abi/struct_def.rs

@@ -1,7 +1,7 @@
 //! Solidity struct definition parsing support
 use crate::abi::{
     error::{bail, format_err, Result},
-    human_readable::{is_whitespace, parse_identifier},
+    human_readable::{is_likely_tuple_not_uint8, is_whitespace, parse_identifier},
     param_type::Reader,
     ParamType,
 };
@@ -333,7 +333,13 @@ fn parse_field_type(s: &str) -> Result<FieldType> {
         input = input[..input.len() - 7].trim_end();
     }
     if let Ok(ty) = Reader::read(input) {
+        // See `AbiParser::parse_type`
+        if is_likely_tuple_not_uint8(&ty, s) {
+            // likely that an unknown type was resolved as `uint8`
+            StructFieldType::parse(input.trim_end())
+        } else {
             Ok(FieldType::Elementary(ty))
+        }
     } else {
         // parsing elementary datatype failed, try struct
         StructFieldType::parse(input.trim_end())
@@ -354,7 +360,16 @@ fn parse_mapping(s: &str) -> Result<MappingType> {
         .map(str::trim)
         .map(Reader::read)??;
 
-    if let ParamType::Array(_) | ParamType::FixedArray(_, _) | ParamType::Tuple(_) = &key_type {
+    let is_illegal_ty = if let ParamType::Array(_) |
+    ParamType::FixedArray(_, _) |
+    ParamType::Tuple(_) = &key_type
+    {
+        true
+    } else {
+        is_likely_tuple_not_uint8(&key_type, s)
+    };
+
+    if is_illegal_ty {
         bail!("Expected elementary mapping key type at `{}` got {:?}", input, key_type)
     }