Add no_main lint

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [E2E] Call builders and extra gas margin option - [#1917](https://github.com/paritytech/ink/pull/1917)
 - Linter: `storage_never_freed` lint - [#1932](https://github.com/paritytech/ink/pull/1932)
 - Linter: `strict_balance_equality` lint - [#1914](https://github.com/paritytech/ink/pull/1914)
+- Linter: `no_main` lint - [#2001](https://github.com/paritytech/ink/pull/2001)
 - Clean E2E configuration parsing - [#1922](https://github.com/paritytech/ink/pull/1922)
 - Make `set_code_hash` generic - [#1906](https://github.com/paritytech/ink/pull/1906)
 

linting/Cargo.toml

@@ -63,6 +63,9 @@ path = "ui/pass/strict_balance_equality.rs"
 [[example]]
 name = "strict_balance_equality_fail"
 path = "ui/fail/strict_balance_equality.rs"
+[[example]]
+name = "no_main_pass"
+path = "ui/pass/no_main.rs"
 
 [package.metadata.rust-analyzer]
 rustc_private = true

linting/src/lib.rs

@@ -32,6 +32,7 @@ extern crate rustc_session;
 extern crate rustc_span;
 
 mod ink_utils;
+mod no_main;
 mod primitive_topic;
 mod storage_never_freed;
 mod strict_balance_equality;
@@ -46,11 +47,13 @@ pub fn register_lints(
         primitive_topic::PRIMITIVE_TOPIC,
         storage_never_freed::STORAGE_NEVER_FREED,
         strict_balance_equality::STRICT_BALANCE_EQUALITY,
+        no_main::NO_MAIN,
     ]);
     lint_store.register_late_pass(|_| Box::new(primitive_topic::PrimitiveTopic));
     lint_store.register_late_pass(|_| Box::new(storage_never_freed::StorageNeverFreed));
     lint_store
         .register_late_pass(|_| Box::new(strict_balance_equality::StrictBalanceEquality));
+    lint_store.register_early_pass(|| Box::new(no_main::NoMain));
 }
 
 #[test]

linting/src/no_main.rs

@@ -0,0 +1,85 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use ast::{
+    AttrStyle,
+    Crate,
+};
+use clippy_utils::diagnostics::span_lint_and_help;
+use if_chain::if_chain;
+use rustc_ast as ast;
+use rustc_lint::{
+    EarlyContext,
+    EarlyLintPass,
+    LintContext,
+};
+use rustc_middle::lint::in_external_macro;
+use rustc_session::{
+    declare_lint,
+    declare_lint_pass,
+};
+use rustc_span::sym;
+
+declare_lint! {
+    /// ## What it does
+    /// Checks if a contract is annotated with the `no_main` inner attribute.
+    ///
+    /// ## Why is this necessary?
+    /// Contracts must be annotated with `no_main` inner attribute when compiled for on-chain
+    /// execution.
+    ///
+    /// ## Example
+    ///
+    /// ```rust
+    /// // Bad: Contract does not contain the `no_main` attribute, so it cannot be compiled to Wasm
+    /// #![cfg_attr(not(feature = "std"), no_std)]
+    ///	#[ink::contract]
+    ///	mod my_contract { /* ... */ }
+    /// ```
+    ///
+    /// Use instead:
+    ///
+    /// ```rust
+    /// #![cfg_attr(not(feature = "std"), no_std, no_main)]
+    ///	#[ink::contract]
+    ///	mod my_contract { /* ... */ }
+    /// ```
+    pub NO_MAIN,
+    Deny,
+    "contract must be annotated with the `no_main` inner attribute"
+}
+
+declare_lint_pass!(NoMain => [NO_MAIN]);
+
+impl EarlyLintPass for NoMain {
+    fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &Crate) {
+        // `no_main` is an `Inner` attribute of `#![cfg_attr(...)]`
+        if krate.attrs.iter().all(|attr| {
+            if_chain! {
+            if !in_external_macro(cx.sess(), attr.span);
+            if let AttrStyle::Inner = attr.style;
+            if attr.has_name(sym::no_main);
+            then { false } else { true }}
+        }) {
+            span_lint_and_help(
+                cx,
+                NO_MAIN,
+                krate.spans.inner_span,
+                "contract must be annotated with the `no_main` inner attribute",
+                None,
+                "consider annotating contract with `#![cfg_attr(not(feature = \"std\"), no_std, no_main)]` or `#![no_main]`"
+            )
+        }
+    }
+}

linting/ui/fail/primitive_topic.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_main)]
+
 pub type TyAlias1 = i32;
 pub type TyAlias2 = TyAlias1;
 

linting/ui/fail/primitive_topic.stderr

@@ -1,25 +1,25 @@
 error: using `#[ink(topic)]` for a field with a primitive number type
-  --> $DIR/primitive_topic.rs:11:9
+  --> $DIR/primitive_topic.rs:13:9
    |
 LL |         value_1: u8,
    |         ^^^^^^^^^^^ help: consider removing `#[ink(topic)]`: `value_1: u8`
    |
    = note: `-D primitive-topic` implied by `-D warnings`
 
 error: using `#[ink(topic)]` for a field with a primitive number type
-  --> $DIR/primitive_topic.rs:14:9
+  --> $DIR/primitive_topic.rs:16:9
    |
 LL |         value_2: Balance,
    |         ^^^^^^^^^^^^^^^^ help: consider removing `#[ink(topic)]`: `value_2: Balance`
 
 error: using `#[ink(topic)]` for a field with a primitive number type
-  --> $DIR/primitive_topic.rs:17:9
+  --> $DIR/primitive_topic.rs:19:9
    |
 LL |         value_3: crate::TyAlias1,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `#[ink(topic)]`: `value_3: crate::TyAlias1`
 
 error: using `#[ink(topic)]` for a field with a primitive number type
-  --> $DIR/primitive_topic.rs:20:9
+  --> $DIR/primitive_topic.rs:22:9
    |
 LL |         value_4: crate::TyAlias2,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `#[ink(topic)]`: `value_4: crate::TyAlias2`

linting/ui/fail/storage_never_freed.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(not(feature = "std"), no_main)]
 #![cfg_attr(dylint_lib = "ink_linting", deny(storage_never_freed))]
 pub type MapAlias1<K, V> = ink::storage::Mapping<K, V>;
 pub type MapAlias2<K, V> = MapAlias1<K, V>;

linting/ui/fail/storage_never_freed.stderr

@@ -1,58 +1,58 @@
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:17:9
+  --> $DIR/storage_never_freed.rs:18:9
    |
 LL |         map_1: Mapping<AccountId, AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 note: the lint level is defined here
-  --> $DIR/storage_never_freed.rs:1:46
+  --> $DIR/storage_never_freed.rs:2:46
    |
 LL | #![cfg_attr(dylint_lib = "ink_linting", deny(storage_never_freed))]
    |                                              ^^^^^^^^^^^^^^^^^^^
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:18:9
+  --> $DIR/storage_never_freed.rs:19:9
    |
 LL |         map_2: Mapping<AccountId, AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:19:9
+  --> $DIR/storage_never_freed.rs:20:9
    |
 LL |         map_3: Mapping<AccountId, AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:20:9
+  --> $DIR/storage_never_freed.rs:21:9
    |
 LL |         map_alias: MapAlias2<AccountId, AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:14:9
+  --> $DIR/storage_never_freed.rs:15:9
    |
 LL |         vec_1: Vec<AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:15:9
+  --> $DIR/storage_never_freed.rs:16:9
    |
 LL |         vec_2: Vec<bool>,
    |         ^^^^^^^^^^^^^^^^
    |
    = help: consider adding operations to remove elements available to the user
 
 error: field's storage cannot be freed
-  --> $DIR/storage_never_freed.rs:16:9
+  --> $DIR/storage_never_freed.rs:17:9
    |
 LL |         vec_subscription: Vec<AccountId>,
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

linting/ui/fail/strict_balance_equality.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_main)]
+
 #[ink::contract]
 pub mod strict_balance_equality {
     #[ink(storage)]

linting/ui/fail/strict_balance_equality.stderr

@@ -1,73 +1,73 @@
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:57:16
+  --> $DIR/strict_balance_equality.rs:59:16
    |
 LL |             if self.env().balance() == 10 { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
    |
    = note: `-D strict-balance-equality` implied by `-D warnings`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:58:16
+  --> $DIR/strict_balance_equality.rs:60:16
    |
 LL |             if value == 11 { /* ... */ }
    |                ^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:59:16
+  --> $DIR/strict_balance_equality.rs:61:16
    |
 LL |             if self.env().balance() == threshold { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:62:16
+  --> $DIR/strict_balance_equality.rs:64:16
    |
 LL |             if self.get_balance_1() == 10 { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:63:16
+  --> $DIR/strict_balance_equality.rs:65:16
    |
 LL |             if self.get_balance_2() == 10 { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:64:16
+  --> $DIR/strict_balance_equality.rs:66:16
    |
 LL |             if self.get_balance_3() == 10 { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:65:16
+  --> $DIR/strict_balance_equality.rs:67:16
    |
 LL |             if self.get_balance_recursive(&10) == 10 { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:69:16
+  --> $DIR/strict_balance_equality.rs:71:16
    |
 LL |             if self.cmp_balance_1(&10) { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:70:16
+  --> $DIR/strict_balance_equality.rs:72:16
    |
 LL |             if self.cmp_balance_2(&self.env().balance(), &threshold) { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:71:16
+  --> $DIR/strict_balance_equality.rs:73:16
    |
 LL |             if self.cmp_balance_3(self.env().balance(), threshold) { /* ... */ }
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:76:16
+  --> $DIR/strict_balance_equality.rs:78:16
    |
 LL |             if res_1 == 10 { /* ... */ }
    |                ^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`
 
 error: dangerous strict balance equality
-  --> $DIR/strict_balance_equality.rs:79:16
+  --> $DIR/strict_balance_equality.rs:81:16
    |
 LL |             if res_2 == 10 { /* ... */ }
    |                ^^^^^^^^^^^ help: consider using non-strict equality operators instead: `<`, `>`

linting/ui/pass/no_main.rs

@@ -0,0 +1,17 @@
+#![cfg_attr(not(feature = "std"), no_std, no_main)]
+
+#[ink::contract]
+pub mod no_main {
+    #[ink(storage)]
+    pub struct NoMain {}
+    impl NoMain {
+        #[ink(constructor)]
+        pub fn new() -> Self {
+            Self {}
+        }
+        #[ink(message)]
+        pub fn do_nothing(&mut self) {}
+    }
+}
+
+fn main() {}

linting/ui/pass/primitive_topic.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_main)]
+
 #[ink::contract]
 pub mod primitive_topic {
 

linting/ui/pass/storage_never_freed.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(not(feature = "std"), no_main)]
 #![cfg_attr(dylint_lib = "ink_linting", deny(storage_never_freed))]
 pub type MapAlias<K, V> = ink::storage::Mapping<K, V>;
 

linting/ui/pass/strict_balance_equality.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_main)]
+
 #[ink::contract]
 pub mod strict_balance_equality {
     #[ink(storage)]