fix(abigen): safe ident underscore followed by numeric (#970)

ethers-contract/ethers-contract-abigen/src/contract/methods.rs

@@ -558,7 +558,7 @@ fn expand_function_name(function: &Function, alias: Option<&MethodAlias>) -> Ide
     if let Some(alias) = alias {
         alias.function_name.clone()
     } else {
-        util::safe_ident(&function.name.to_snake_case())
+        util::safe_ident(&util::safe_snake_case(&function.name))
     }
 }
 
@@ -567,7 +567,7 @@ fn expand_call_struct_name(function: &Function, alias: Option<&MethodAlias>) ->
     let name = if let Some(alias) = alias {
         format!("{}Call", alias.struct_name)
     } else {
-        format!("{}Call", function.name.to_pascal_case())
+        format!("{}Call", util::safe_pascal_case(&function.name))
     };
     util::ident(&name)
 }
@@ -577,7 +577,7 @@ fn expand_call_struct_variant_name(function: &Function, alias: Option<&MethodAli
     if let Some(alias) = alias {
         alias.struct_name.clone()
     } else {
-        util::safe_ident(&function.name.to_pascal_case())
+        util::safe_ident(&util::safe_pascal_case(&function.name))
     }
 }
 

ethers-contract/ethers-contract-abigen/src/util.rs

@@ -21,6 +21,25 @@ pub fn safe_ident(name: &str) -> Ident {
     syn::parse_str::<SynIdent>(name).unwrap_or_else(|_| ident(&format!("{}_", name)))
 }
 
+///  Converts a `&str` to `snake_case` `String` while respecting identifier rules
+pub fn safe_snake_case(ident: &str) -> String {
+    safe_identifier_name(ident.to_snake_case())
+}
+
+///  Converts a `&str` to `PascalCase` `String` while respecting identifier rules
+pub fn safe_pascal_case(ident: &str) -> String {
+    safe_identifier_name(ident.to_pascal_case())
+}
+
+/// respects identifier rules, such as, an identifier must not start with a numeric char
+fn safe_identifier_name(name: String) -> String {
+    if name.starts_with(|c: char| c.is_numeric()) {
+        format!("_{}", name)
+    } else {
+        name
+    }
+}
+
 /// Expands an identifier as snakecase and preserve any leading or trailing underscores
 pub fn safe_snake_case_ident(name: &str) -> Ident {
     let i = name.to_snake_case();

ethers-contract/tests/abigen.rs

@@ -374,6 +374,23 @@ fn can_handle_unique_underscore_functions() {
     let _contract_call = ConsoleLogCalls::Log2(call);
 }
 
+#[test]
+fn can_handle_underscore_numeric() {
+    abigen!(
+        Test,
+        r#"[
+            _100pct(string)
+        ]"#
+    );
+    let call = _100PctCall("message".to_string());
+
+    let provider = Arc::new(Provider::new(MockProvider::new()));
+    let contract = Test::new(Address::default(), Arc::clone(&provider));
+    // NOTE: this seems to be weird behaviour of `Inflector::to_snake_case` which turns "100pct" ->
+    // "10_0pct"
+    let _call = contract._10_0pct("hello".to_string());
+}
+
 #[test]
 fn can_handle_duplicates_with_same_name() {
     abigen!(