Add detailed diagnostics for Rust-style enums

sway-error/src/error.rs

@@ -2724,6 +2724,29 @@ impl ToDiagnostic for CompileError {
             },
             Parse { error } => {
                 match &error.kind {
+                    ParseErrorKind::MissingColonInEnumTypeField { variant_name, tuple_contents } => Diagnostic {
+                        reason: Some(Reason::new(code(1), "Enum variant declaration is not valid".to_string())),
+                        issue: Issue::error(
+                            source_engine,
+                            error.span.clone(),
+                            format!("`{}` is not a valid enum variant declaration.", error.span.as_str()),
+                        ),
+                        hints: vec![
+                            if let Some(tuple_contents) = tuple_contents {
+                                Hint::help(
+                                    source_engine,
+                                    error.span.clone(),
+                                    format!("Did you mean `{}: ({})`?", variant_name, tuple_contents.as_str())
+                                )
+                            } else {
+                                Hint::none()
+                            }
+                        ],
+                        help: vec![
+                            "In Sway, enum variants are in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`.".to_string(),
+                            "E.g., `Foo: (), `Bar: u64`, or `Bar: (bool, u32)`.".to_string(),
+                        ],
+                    },
                     ParseErrorKind::UnassignableExpression { erroneous_expression_kind, erroneous_expression_span } => Diagnostic {
                         reason: Some(Reason::new(code(1), "Expression cannot be assigned to".to_string())),
                         // A bit of a special handling for parentheses, because they are the only

sway-error/src/parser_error.rs

@@ -118,7 +118,10 @@ pub enum ParseErrorKind {
     #[error("Expected a path type.")]
     ExpectedPathType,
     #[error("Expected ':'. Enum variants must be in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`. E.g., `Foo: (), or `Bar: (bool, u32)`.")]
-    MissingColonInEnumTypeField,
+    MissingColonInEnumTypeField {
+        variant_name: Ident,
+        tuple_contents: Option<Span>,
+    },
     #[error("Expected storage key of type U256.")]
     ExpectedStorageKeyU256,
 }

sway-parse/src/item/mod.rs

@@ -10,6 +10,8 @@ use sway_ast::{
     ItemTypeAlias, ItemUse, Submodule, TraitType, TypeField,
 };
 use sway_error::parser_error::ParseErrorKind;
+use sway_types::ast::Delimiter;
+use sway_types::{Ident, Span, Spanned};
 
 mod item_abi;
 mod item_configurable;
@@ -95,16 +97,67 @@ impl Parse for ItemKind {
 impl Parse for TypeField {
     fn parse(parser: &mut Parser) -> ParseResult<TypeField> {
         let visibility = parser.take();
-        Ok(TypeField {
-            visibility,
-            name: parser.parse()?,
-            colon_token: if parser.peek::<ColonToken>().is_some() {
-                parser.parse()
-            } else {
-                Err(parser.emit_error(ParseErrorKind::MissingColonInEnumTypeField))
-            }?,
-            ty: parser.parse()?,
-        })
+        let name: Ident = parser.parse()?;
+        let name_span = name.span();
+
+        // Check for the common, valid case `Variant: Type` first.
+        if parser.peek::<ColonToken>().is_some() {
+            let colon_token = parser.parse()?;
+            let ty = parser.parse()?;
+            return Ok(TypeField {
+                visibility,
+                name,
+                colon_token,
+                ty,
+            });
+        }
+
+        // --- Colon was not found after name, proceed with error handling ---
+
+        // Case 1: Check for invalid struct-like variant `Variant { ... }`
+        if let Some((_inner_parser, brace_span)) = parser.enter_delimited(Delimiter::Brace) {
+            let error_span = Span::join(name_span, &brace_span);
+            return Err(parser.emit_error_with_span(
+                ParseErrorKind::MissingColonInEnumTypeField {
+                    variant_name: name,
+                    tuple_contents: None, // Not a tuple issue
+                },
+                error_span,
+            ));
+        }
+
+        // Case 2: Check for invalid tuple-like variant `Variant ( ... )` (missing colon)
+        if let Some((inner_parser, paren_span)) = parser.enter_delimited(Delimiter::Parenthesis) {
+            let tuple_contents_span = inner_parser.full_span().clone();
+            let error_span = Span::join(name_span.clone(), &paren_span);
+            return Err(parser.emit_error_with_span(
+                ParseErrorKind::MissingColonInEnumTypeField {
+                    variant_name: name,
+                    tuple_contents: Some(tuple_contents_span),
+                },
+                error_span,
+            ));
+        }
+
+        // Case 3: Check for unit-like variant `Variant,` or `Variant` (at end)
+        if parser.is_empty() || parser.peek::<sway_ast::CommaToken>().is_some() {
+            return Err(parser.emit_error_with_span(
+                ParseErrorKind::MissingColonInEnumTypeField {
+                    variant_name: name,
+                    tuple_contents: Some(Span::dummy()), // Indicate unit-like
+                },
+                name_span,
+            ));
+        }
+
+        // Case 4: Something else follows where a colon was expected
+        Err(parser.emit_error_with_span(
+            ParseErrorKind::MissingColonInEnumTypeField {
+                variant_name: name,
+                tuple_contents: None,
+            },
+            name_span,
+        ))
     }
 }
 

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

@@ -13,6 +13,16 @@ enum Enum2 {
   G(u32, u32),   // Also illegal, but shadowed by previous error
 }
 
+enum Enum3 {
+  F(bool, u32, str[4]), // Illegal
+  G(u32, u32),          // Also illegal, but shadowed by previous error
+}
+
+enum Enum4 {
+  A { x: i32, y: i32 }, // Illegal
+  Another(u64, bool),   // Also illegal, but shadowed by previous error
+}
+
 fn main() {
 }
 

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

@@ -1,11 +1,32 @@
 category = "fail"
 
 # check: $()error
-# check: enum_rust_like/src/main.sw:7:5
+# check: enum_rust_like/src/main.sw:7:3
 # check: $()Ok,    // Illegal
-# nextln: $()Expected ':'. Enum variants must be in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`. E.g., `Foo: (), or `Bar: (bool, u32)`.
+# nextln: $()`Ok` is not a valid enum variant declaration.
+# nextln: $()Did you mean `Ok: ()`?
+# check: $()In Sway, enum variants are in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`.
+# nextln: $()E.g., `Foo: (), `Bar: u64`, or `Bar: (bool, u32)`.
 
 # check: $()error
-# check: enum_rust_like/src/main.sw:12:4
+# check: enum_rust_like/src/main.sw:12:3
 # check: $()F(u32),        // Illegal
-# nextln: $()Expected ':'. Enum variants must be in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`. E.g., `Foo: (), or `Bar: (bool, u32)`.
+# nextln: $()`F(u32)` is not a valid enum variant declaration.
+# nextln: $()Did you mean `F: (u32)`?
+# check: $()In Sway, enum variants are in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`.
+# nextln: $()E.g., `Foo: (), `Bar: u64`, or `Bar: (bool, u32)`.
+
+# check: $()error
+# check: enum_rust_like/src/main.sw:17:3
+# check: $()F(bool, u32, str[4]), // Illegal
+# nextln: $()`F(bool, u32, str[4])` is not a valid enum variant declaration.
+# nextln: $()Did you mean `F: (bool, u32, str[4])`?
+# check: $()In Sway, enum variants are in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`.
+# nextln: $()E.g., `Foo: (), `Bar: u64`, or `Bar: (bool, u32)`.
+
+# check: $()error
+# check: enum_rust_like/src/main.sw:22:3
+# check: $()A { x: i32, y: i32 }, // Illegal
+# nextln: $()`A { x: i32, y: i32 }` is not a valid enum variant declaration.
+# check: $()In Sway, enum variants are in the form `Variant: ()`, `Variant: <type>`, or `Variant: (<type1>, ..., <typeN>)`.
+# nextln: $()E.g., `Foo: (), `Bar: u64`, or `Bar: (bool, u32)`.