Recover class Foo { .. } as struct (FuelLabs#2751)

* recover 'class Foo { .. }' as struct

* class => struct recovery: tweak wording

Co-authored-by: Mohammad Fawaz <[email protected]>

sway-ast/src/keywords.rs

@@ -54,6 +54,7 @@ define_keyword!(PubToken, "pub");
 define_keyword!(UseToken, "use");
 define_keyword!(AsToken, "as");
 define_keyword!(StructToken, "struct");
+define_keyword!(ClassToken, "class"); // Not in the language! Exists for recovery.
 define_keyword!(EnumToken, "enum");
 define_keyword!(SelfToken, "self");
 define_keyword!(FnToken, "fn");

sway-parse/src/error.rs

@@ -74,6 +74,8 @@ pub enum ParseErrorKind {
     UnnecessaryVisibilityQualifier { visibility: Ident },
     #[error("Expected a doc comment.")]
     ExpectedDocComment,
+    #[error("Use the `struct` keyword to define records, instead of `class`.")]
+    UnexpectedClass,
 }
 
 #[derive(Debug, Error, Clone, PartialEq, Eq, Hash)]

sway-parse/src/item/item_struct.rs

@@ -1,13 +1,22 @@
-use crate::{Parse, ParseResult, Parser};
+use crate::{Parse, ParseErrorKind, ParseResult, Parser};
 
-use sway_ast::keywords::{OpenAngleBracketToken, WhereToken};
+use sway_ast::keywords::{ClassToken, Keyword, OpenAngleBracketToken, StructToken, WhereToken};
 use sway_ast::ItemStruct;
+use sway_types::Spanned;
 
 impl Parse for ItemStruct {
     fn parse(parser: &mut Parser) -> ParseResult<ItemStruct> {
+        // Parse `struct`, or recover on `class` as if `struct` was written.
+        let struct_token = if let Some(ct) = parser.take::<ClassToken>() {
+            parser.emit_error(ParseErrorKind::UnexpectedClass);
+            StructToken::new(ct.span())
+        } else {
+            parser.parse()?
+        };
+
         Ok(ItemStruct {
             visibility: None,
-            struct_token: parser.parse()?,
+            struct_token,
             name: parser.parse()?,
             generics: parser.guarded_parse::<OpenAngleBracketToken, _>()?,
             where_clause_opt: parser.guarded_parse::<WhereToken, _>()?,

sway-parse/src/item/mod.rs

@@ -1,8 +1,9 @@
 use crate::{Parse, ParseErrorKind, ParseResult, ParseToEnd, Parser, ParserConsumed};
 
 use sway_ast::keywords::{
-    AbiToken, ConstToken, EnumToken, FnToken, ImplToken, MutToken, OpenAngleBracketToken, RefToken,
-    SelfToken, StorageToken, StructToken, TraitToken, UseToken, WhereToken,
+    AbiToken, ClassToken, ConstToken, EnumToken, FnToken, ImplToken, MutToken,
+    OpenAngleBracketToken, RefToken, SelfToken, StorageToken, StructToken, TraitToken, UseToken,
+    WhereToken,
 };
 use sway_ast::{
     FnArg, FnArgs, FnSignature, ItemConst, ItemEnum, ItemFn, ItemKind, ItemStruct, ItemTrait,
@@ -30,6 +31,9 @@ impl Parse for ItemKind {
         let kind = if let Some(mut item) = parser.guarded_parse::<UseToken, ItemUse>()? {
             item.visibility = visibility.take();
             ItemKind::Use(item)
+        } else if let Some(mut item) = parser.guarded_parse::<ClassToken, ItemStruct>()? {
+            item.visibility = visibility.take();
+            ItemKind::Struct(item)
         } else if let Some(mut item) = parser.guarded_parse::<StructToken, ItemStruct>()? {
             item.visibility = visibility.take();
             ItemKind::Struct(item)

sway-parse/src/keywords.rs

@@ -43,6 +43,7 @@ keyword_impls! {
     UseToken,
     AsToken,
     StructToken,
+    ClassToken,
     EnumToken,
     SelfToken,
     FnToken,

test/src/e2e_vm_tests/test_programs/should_fail/recover_class_as_struct/Forc.lock

@@ -0,0 +1,4 @@
+[[package]]
+name = 'recover_class_as_struct'
+source = 'root'
+dependencies = []

test/src/e2e_vm_tests/test_programs/should_fail/recover_class_as_struct/Forc.toml

@@ -0,0 +1,6 @@
+[project]
+name = "recover_class_as_struct"
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+implicit-std = false

test/src/e2e_vm_tests/test_programs/should_fail/recover_class_as_struct/src/main.sw

@@ -0,0 +1,8 @@
+contract;
+
+class Foo {
+}
+
+fn bar() -> bool {
+    0 // recovery witness
+}

test/src/e2e_vm_tests/test_programs/should_fail/recover_class_as_struct/test.toml

@@ -0,0 +1,4 @@
+category = "fail"
+
+# check: $()Use the `struct` keyword to define records, instead of `class`.
+# check: $()Mismatched types.