Restrict wildcard selectors to have exactly one other message

crates/e2e/macro/src/config.rs

@@ -57,7 +57,7 @@ impl TryFrom<ast::AttributeArgs> for E2EConfig {
                         "E2E test",
                     ))
                 }
-                if let ast::PathOrLit::Lit(syn::Lit::Str(lit_str)) = &arg.value {
+                if let ast::MetaValue::Lit(syn::Lit::Str(lit_str)) = &arg.value {
                     additional_contracts = Some((lit_str.clone(), arg))
                 } else {
                     return Err(format_err_spanned!(
@@ -69,7 +69,7 @@ impl TryFrom<ast::AttributeArgs> for E2EConfig {
                 if let Some((_, ast)) = environment {
                     return Err(duplicate_config_err(ast, arg, "environment", "E2E test"))
                 }
-                if let ast::PathOrLit::Path(path) = &arg.value {
+                if let ast::MetaValue::Path(path) = &arg.value {
                     environment = Some((path.clone(), arg))
                 } else {
                     return Err(format_err_spanned!(

crates/e2e/src/builders.rs

@@ -73,6 +73,15 @@ impl<E, RetType> Message<E, RetType>
 where
     E: Environment,
 {
+    /// Create a new message from the given account id and encoded message data.
+    pub fn new(account_id: E::AccountId, exec_input: Vec<u8>) -> Self {
+        Self {
+            account_id,
+            exec_input,
+            _return_type: Default::default(),
+        }
+    }
+
     /// The account id of the contract being called to invoke the message.
     pub fn account_id(&self) -> &E::AccountId {
         &self.account_id

crates/e2e/src/lib.rs

@@ -27,6 +27,7 @@ mod xts;
 
 pub use builders::{
     build_message,
+    Message,
     MessageBuilder,
 };
 pub use client::{

crates/ink/ir/Cargo.toml

@@ -24,6 +24,7 @@ proc-macro2 = "1.0"
 itertools = { version = "0.10", default-features = false }
 either = { version = "1.5", default-features = false }
 blake2 = "0.10"
+ink_prelude = { version = "4.1.0", path = "../../prelude/", default-features = false }
 
 [features]
 default = ["std"]

crates/ink/ir/src/ast/attr_args.rs

@@ -51,7 +51,7 @@ impl Parse for AttributeArgs {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::ast::PathOrLit;
+    use crate::ast::MetaValue;
     use quote::quote;
 
     impl AttributeArgs {
@@ -81,7 +81,7 @@ mod tests {
             AttributeArgs::new(vec![MetaNameValue {
                 name: syn::parse_quote! { name },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Lit(syn::parse_quote! { true }),
+                value: MetaValue::Lit(syn::parse_quote! { true }),
             }])
         )
     }
@@ -93,7 +93,7 @@ mod tests {
             AttributeArgs::new(vec![MetaNameValue {
                 name: syn::parse_quote! { name },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Lit(syn::parse_quote! { "string literal" }),
+                value: MetaValue::Lit(syn::parse_quote! { "string literal" }),
             }])
         )
     }
@@ -105,7 +105,7 @@ mod tests {
             AttributeArgs::new(vec![MetaNameValue {
                 name: syn::parse_quote! { name },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Path(syn::parse_quote! { MyIdentifier }),
+                value: MetaValue::Path(syn::parse_quote! { MyIdentifier }),
             }])
         )
     }
@@ -117,7 +117,7 @@ mod tests {
             AttributeArgs::new(vec![MetaNameValue {
                 name: syn::parse_quote! { name },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Path(syn::parse_quote! { ::this::is::my::Path }),
+                value: MetaValue::Path(syn::parse_quote! { ::this::is::my::Path }),
             }])
         )
     }
@@ -130,7 +130,7 @@ mod tests {
             AttributeArgs::new(vec![MetaNameValue {
                 name: syn::parse_quote! { name },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Path(
+                value: MetaValue::Path(
                     syn::parse_quote! { this::is::my::relative::Path }
                 ),
             }])
@@ -143,7 +143,7 @@ mod tests {
         expected_args.push_value(MetaNameValue {
             name: syn::parse_quote! { name },
             eq_token: syn::parse_quote! { = },
-            value: PathOrLit::Path(syn::parse_quote! { value }),
+            value: MetaValue::Path(syn::parse_quote! { value }),
         });
         expected_args.push_punct(<Token![,]>::default());
         assert_eq!(
@@ -169,27 +169,27 @@ mod tests {
                 MetaNameValue {
                     name: syn::parse_quote! { name1 },
                     eq_token: syn::parse_quote! { = },
-                    value: PathOrLit::Path(syn::parse_quote! { ::root::Path }),
+                    value: MetaValue::Path(syn::parse_quote! { ::root::Path }),
                 },
                 MetaNameValue {
                     name: syn::parse_quote! { name2 },
                     eq_token: syn::parse_quote! { = },
-                    value: PathOrLit::Lit(syn::parse_quote! { false }),
+                    value: MetaValue::Lit(syn::parse_quote! { false }),
                 },
                 MetaNameValue {
                     name: syn::parse_quote! { name3 },
                     eq_token: syn::parse_quote! { = },
-                    value: PathOrLit::Lit(syn::parse_quote! { "string literal" }),
+                    value: MetaValue::Lit(syn::parse_quote! { "string literal" }),
                 },
                 MetaNameValue {
                     name: syn::parse_quote! { name4 },
                     eq_token: syn::parse_quote! { = },
-                    value: PathOrLit::Lit(syn::parse_quote! { 42 }),
+                    value: MetaValue::Lit(syn::parse_quote! { 42 }),
                 },
                 MetaNameValue {
                     name: syn::parse_quote! { name5 },
                     eq_token: syn::parse_quote! { = },
-                    value: PathOrLit::Lit(syn::parse_quote! { 7.7 }),
+                    value: MetaValue::Lit(syn::parse_quote! { 7.7 }),
                 },
             ])
         )

crates/ink/ir/src/ast/meta.rs

@@ -70,7 +70,7 @@ impl ToTokens for Meta {
 pub struct MetaNameValue {
     pub name: syn::Path,
     pub eq_token: syn::token::Eq,
-    pub value: PathOrLit,
+    pub value: MetaValue,
 }
 
 impl Parse for MetaNameValue {
@@ -107,35 +107,40 @@ impl MetaNameValue {
     }
 }
 
-/// Either a path or a literal.
+/// Represents a value in a meta name-value pair.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum PathOrLit {
+pub enum MetaValue {
     Path(syn::Path),
     Lit(syn::Lit),
+    Symbol(Symbol),
 }
 
-impl Parse for PathOrLit {
+impl Parse for MetaValue {
     fn parse(input: ParseStream) -> Result<Self, syn::Error> {
+        if input.peek(Token![_]) || input.peek(Token![@]) {
+            return input.parse::<Symbol>().map(MetaValue::Symbol)
+        }
         if input.fork().peek(syn::Lit) {
-            return input.parse::<syn::Lit>().map(PathOrLit::Lit)
+            return input.parse::<syn::Lit>().map(MetaValue::Lit)
         }
         if input.fork().peek(Ident::peek_any) || input.fork().peek(Token![::]) {
-            return input.call(parse_meta_path).map(PathOrLit::Path)
+            return input.call(parse_meta_path).map(MetaValue::Path)
         }
-        Err(input.error("cannot parse into either literal or path"))
+        Err(input.error("expected a literal, a path or a punct for a meta value"))
     }
 }
 
-impl ToTokens for PathOrLit {
+impl ToTokens for MetaValue {
     fn to_tokens(&self, tokens: &mut TokenStream2) {
         match self {
             Self::Lit(lit) => lit.to_tokens(tokens),
             Self::Path(path) => path.to_tokens(tokens),
+            Self::Symbol(symbol) => symbol.to_tokens(tokens),
         }
     }
 }
 
-impl PathOrLit {
+impl MetaValue {
     /// Returns the value of the literal if it is a boolean literal.
     pub fn as_bool(&self) -> Option<bool> {
         match self {
@@ -161,6 +166,33 @@ impl PathOrLit {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum Symbol {
+    Underscore(Token![_]),
+    AtSign(Token![@]),
+}
+
+impl Parse for Symbol {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        if input.peek(Token![_]) {
+            Ok(Symbol::Underscore(input.parse()?))
+        } else if input.peek(Token![@]) {
+            Ok(Symbol::AtSign(input.parse()?))
+        } else {
+            Err(input.error("expected either a `_` or a `@` symbol"))
+        }
+    }
+}
+
+impl ToTokens for Symbol {
+    fn to_tokens(&self, tokens: &mut TokenStream2) {
+        match self {
+            Self::Underscore(underscore) => underscore.to_tokens(tokens),
+            Self::AtSign(at_sign) => at_sign.to_tokens(tokens),
+        }
+    }
+}
+
 /// Like [`syn::Path::parse_mod_style`] but accepts keywords in the path.
 ///
 /// # Note
@@ -194,7 +226,10 @@ fn parse_meta_path(input: ParseStream) -> Result<syn::Path, syn::Error> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::ast::PathOrLit;
+    use crate::ast::{
+        MetaValue,
+        Symbol,
+    };
     use quote::quote;
 
     #[test]
@@ -204,7 +239,7 @@ mod tests {
             Meta::NameValue(MetaNameValue {
                 name: syn::parse_quote! { selector },
                 eq_token: syn::parse_quote! { = },
-                value: PathOrLit::Path(syn::Path::from(quote::format_ident!("_"))),
+                value: MetaValue::Symbol(Symbol::Underscore(syn::parse_quote! { _ })),
             })
         )
     }

crates/ink/ir/src/ast/mod.rs

@@ -32,6 +32,7 @@ pub use self::{
     meta::{
         Meta,
         MetaNameValue,
-        PathOrLit,
+        MetaValue,
+        Symbol,
     },
 };

crates/ink/ir/src/ir/attrs.rs

@@ -15,6 +15,7 @@
 use core::result::Result;
 use std::collections::HashMap;
 
+use ink_prelude::IIP2_WILDCARD_COMPLEMENT_SELECTOR;
 use proc_macro2::{
     Span,
     TokenStream as TokenStream2,
@@ -517,22 +518,27 @@ pub enum SelectorOrWildcard {
     /// annotated with the wildcard selector will be invoked.
     Wildcard,
     /// A user provided selector.
-    UserProvided(ir::Selector),
+    UserProvided(Selector),
 }
 
 impl SelectorOrWildcard {
     /// Create a new `SelectorOrWildcard::Selector` from the supplied bytes.
-    fn selector(bytes: [u8; 4]) -> SelectorOrWildcard {
+    fn selector(bytes: [u8; 4]) -> Self {
         SelectorOrWildcard::UserProvided(Selector::from(bytes))
     }
+
+    /// The selector of the wildcard complement message.
+    pub fn wildcard_complement() -> Self {
+        Self::selector(IIP2_WILDCARD_COMPLEMENT_SELECTOR)
+    }
 }
 
-impl TryFrom<&ast::PathOrLit> for SelectorOrWildcard {
+impl TryFrom<&ast::MetaValue> for SelectorOrWildcard {
     type Error = syn::Error;
 
-    fn try_from(value: &ast::PathOrLit) -> Result<Self, Self::Error> {
+    fn try_from(value: &ast::MetaValue) -> Result<Self, Self::Error> {
         match value {
-            ast::PathOrLit::Lit(lit) => {
+            ast::MetaValue::Lit(lit) => {
                 if let syn::Lit::Str(_) = lit {
                     return Err(format_err_spanned!(
                         lit,
@@ -557,16 +563,19 @@ impl TryFrom<&ast::PathOrLit> for SelectorOrWildcard {
                     "expected 4-digit hexcode for `selector` argument, e.g. #[ink(selector = 0xC0FEBABE]"
                 ))
             }
-            ast::PathOrLit::Path(path) => {
-                if path.is_ident("_") {
-                    Ok(SelectorOrWildcard::Wildcard)
-                } else {
-                    Err(format_err_spanned!(
-                        path,
-                        "expected `selector` argument to be either a 4-digit hexcode or `_`"
-                    ))
+            ast::MetaValue::Symbol(symbol) => {
+                match symbol {
+                    ast::Symbol::Underscore(_) => Ok(SelectorOrWildcard::Wildcard),
+                    ast::Symbol::AtSign(_) => Ok(SelectorOrWildcard::wildcard_complement()),
                 }
             }
+            ast::MetaValue::Path(path) => {
+                Err(format_err_spanned!(
+                    path,
+                    "unexpected path for `selector` argument, expected a 4-digit hexcode or one of \
+                    the wildcard symbols: `_` or `@`"
+                ))
+            }
         }
     }
 }
@@ -587,11 +596,11 @@ pub struct Namespace {
     bytes: Vec<u8>,
 }
 
-impl TryFrom<&ast::PathOrLit> for Namespace {
+impl TryFrom<&ast::MetaValue> for Namespace {
     type Error = syn::Error;
 
-    fn try_from(value: &ast::PathOrLit) -> Result<Self, Self::Error> {
-        if let ast::PathOrLit::Lit(syn::Lit::Str(lit_str)) = value {
+    fn try_from(value: &ast::MetaValue) -> Result<Self, Self::Error> {
+        if let ast::MetaValue::Lit(syn::Lit::Str(lit_str)) = value {
             let argument = lit_str.value();
             syn::parse_str::<syn::Ident>(&argument).map_err(|_error| {
                 format_err_spanned!(

crates/ink/ir/src/ir/config.rs

@@ -45,7 +45,7 @@ impl TryFrom<ast::AttributeArgs> for Config {
                 if let Some((_, ast)) = env {
                     return Err(duplicate_config_err(ast, arg, "env", "contract"))
                 }
-                if let ast::PathOrLit::Path(path) = &arg.value {
+                if let ast::MetaValue::Path(path) = &arg.value {
                     env = Some((Environment { path: path.clone() }, arg))
                 } else {
                     return Err(format_err_spanned!(

crates/ink/ir/src/ir/item_impl/callable.rs

@@ -120,6 +120,10 @@ where
         <C as Callable>::has_wildcard_selector(self.callable)
     }
 
+    fn has_wildcard_complement_selector(&self) -> bool {
+        <C as Callable>::has_wildcard_complement_selector(self.callable)
+    }
+
     fn visibility(&self) -> Visibility {
         <C as Callable>::visibility(self.callable)
     }
@@ -169,6 +173,9 @@ pub trait Callable {
     /// Returns `true` if the ink! callable is flagged as a wildcard selector.
     fn has_wildcard_selector(&self) -> bool;
 
+    /// Returns `true` if the ink! callable is flagged as a wildcard complement selector.
+    fn has_wildcard_complement_selector(&self) -> bool;
+
     /// Returns the visibility of the ink! callable.
     fn visibility(&self) -> Visibility;
 

crates/ink/ir/src/ir/item_impl/constructor.rs

@@ -185,10 +185,11 @@ impl Callable for Constructor {
     }
 
     fn has_wildcard_selector(&self) -> bool {
-        if let Some(SelectorOrWildcard::Wildcard) = self.selector {
-            return true
-        }
-        false
+        matches!(self.selector, Some(SelectorOrWildcard::Wildcard))
+    }
+
+    fn has_wildcard_complement_selector(&self) -> bool {
+        self.selector == Some(SelectorOrWildcard::wildcard_complement())
     }
 
     fn is_payable(&self) -> bool {