From c3d8a85eb5ab75e1ab4fc3044aab320ea98132c7 Mon Sep 17 00:00:00 2001
From: Dunqing <dengqing0821@gmail.com>
Date: Sat, 27 Apr 2024 22:08:02 +0800
Subject: [PATCH] feat(semantic): report that enum member must have initializer
 (#3113)

See
https://www.typescriptlang.org/play/?target=99#code/KYOwrgtgBAglDeAoKKoEMoF4oFk0BcALAOgGcBLEACgEYBKAGmVQCMmBfRRUSKAIQTMUGbACIaAJgDMopqihtEnRABtg+KADMwIAMZYoVOlgB8USVIDc3cNADCg+SK07dRuaw6IgA
---
 crates/oxc_semantic/src/checker/typescript.rs | 30 +++++++++++++++++++
 .../transform_conformance/typescript.snap.md  | 18 ++++++-----
 2 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/crates/oxc_semantic/src/checker/typescript.rs b/crates/oxc_semantic/src/checker/typescript.rs
index 48b069832..b0e690231 100644
--- a/crates/oxc_semantic/src/checker/typescript.rs
+++ b/crates/oxc_semantic/src/checker/typescript.rs
@@ -25,6 +25,7 @@ impl EarlyErrorTypeScript {
                 check_ts_type_parameter_declaration(declaration, ctx);
             }
             AstKind::TSModuleDeclaration(decl) => check_ts_module_declaration(decl, ctx),
+            AstKind::TSEnumDeclaration(decl) => check_ts_enum_declaration(decl, ctx),
             _ => {}
         }
     }
@@ -158,3 +159,32 @@ fn check_ts_module_declaration<'a>(decl: &TSModuleDeclaration<'a>, ctx: &Semanti
         }
     }
 }
+
+fn check_ts_enum_declaration(decl: &TSEnumDeclaration<'_>, ctx: &SemanticBuilder<'_>) {
+    #[derive(Debug, Error, Diagnostic)]
+    #[error("Enum member must have initializer.")]
+    #[diagnostic()]
+    struct EnumMemberMustHaveInitializer(#[label] Span);
+
+    let mut need_initializer = false;
+
+    decl.members.iter().for_each(|member| {
+        if let Some(initializer) = &member.initializer {
+            need_initializer = !matches!(
+                initializer,
+                // A = 1
+                Expression::NumericLiteral(_)
+                    // B = A
+                    | Expression::Identifier(_)
+                    // C = E.D
+                    | Expression::MemberExpression(_)
+                    // D = 1 + 2
+                    | Expression::BinaryExpression(_)
+                    // E = -1
+                    | Expression::UnaryExpression(_)
+            );
+        } else if need_initializer {
+            ctx.error(EnumMemberMustHaveInitializer(member.span));
+        }
+    });
+}
diff --git a/tasks/transform_conformance/typescript.snap.md b/tasks/transform_conformance/typescript.snap.md
index e06414256..663a7982e 100644
--- a/tasks/transform_conformance/typescript.snap.md
+++ b/tasks/transform_conformance/typescript.snap.md
@@ -983,14 +983,16 @@ var A = (A => {
 ```
 
 # babel/packages/babel-plugin-transform-typescript/test/fixtures/enum/non-foldable-constant/input.ts
-```typescript
-var E = (E => {
-	const a = Math.sin(1);
-	E[E['a'] = a] = 'a';
-	const b = 1 + a;
-	E[E['b'] = b] = 'b';
-	return E;
-})(E || {});
+```error
+
+  × Enum member must have initializer.
+   ╭─[babel/packages/babel-plugin-transform-typescript/test/fixtures/enum/non-foldable-constant/input.ts:3:5]
+ 2 │     a = Math.sin(1),
+ 3 │     b,
+   ·     ─
+ 4 │ }
+   ╰────
+
 
 ```