feat(parser): improve error message for missing function body

crates/oxc_parser/src/diagnostics.rs

@@ -1082,3 +1082,10 @@ pub fn invalid_rest_assignment_target(span: Span) -> OxcDiagnostic {
 pub fn modifiers_cannot_appear_here(span: Span) -> OxcDiagnostic {
     ts_error("1184", "Modifiers cannot appear here.").with_label(span)
 }
+
+#[cold]
+pub fn expect_function_body(span: Span) -> OxcDiagnostic {
+    OxcDiagnostic::error("Expected function body")
+        .with_label(span)
+        .with_help("Add a function body (`{}`).")
+}

crates/oxc_parser/src/js/function.rs

@@ -134,7 +134,7 @@ impl<'a> ParserImpl<'a> {
         self.ctx =
             self.ctx.and_in(ctx.has_in()).and_await(ctx.has_await()).and_yield(ctx.has_yield());
         if !self.is_ts && body.is_none() {
-            return self.unexpected();
+            return self.fatal_error(diagnostics::expect_function_body(self.end_span(span)));
         }
         let function_type = match func_kind {
             FunctionKind::Declaration | FunctionKind::DefaultExport => {

tasks/coverage/snapshots/parser_babel.snap

@@ -4596,11 +4596,12 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ·            ╰── `}` expected
    ╰────
 
-  × Unexpected token
-   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/268/input.js:1:14]
+  × Expected function body
+   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/268/input.js:1:1]
  1 │ function a() 1 // expression closure is not supported
-   ·              ─
+   · ────────────
    ╰────
+  help: Add a function body (`{}`).
 
   × Unexpected token
    ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/273/input.js:1:10]
@@ -4634,10 +4635,12 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ·                  ─────
    ╰────
 
-  × Unexpected token
-   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/278/input.js:1:24]
+  × Expected function body
+   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/278/input.js:1:1]
  1 │ function f(a, ...b = 0)
+   · ───────────────────────
    ╰────
+  help: Add a function body (`{}`).
 
   × Identifier `a` has already been declared
    ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/280/input.js:1:26]
@@ -4815,23 +4818,26 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ·  ───
    ╰────
 
-  × Unexpected token
-   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/340/input.js:1:16]
+  × Expected function body
+   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/340/input.js:1:13]
  1 │ x = { method() 42 }
-   ·                ──
+   ·             ──
    ╰────
+  help: Add a function body (`{}`).
 
-  × Unexpected token
-   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/341/input.js:1:20]
+  × Expected function body
+   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/341/input.js:1:17]
  1 │ x = { get method() 42 }
-   ·                    ──
+   ·                 ──
    ╰────
+  help: Add a function body (`{}`).
 
-  × Unexpected token
-   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/342/input.js:1:23]
+  × Expected function body
+   ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/342/input.js:1:17]
  1 │ x = { set method(val) v = val }
-   ·                       ─
+   ·                 ─────
    ╰────
+  help: Add a function body (`{}`).
 
   × 'super' can only be used with function calls or in property accesses
    ╭─[babel/packages/babel-parser/test/fixtures/es2015/uncategorised/344/input.js:1:1]

tasks/coverage/snapshots/parser_typescript.snap

@@ -7191,13 +7191,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  16 │     b = 10;
     ╰────
 
-  × Unexpected token
-   ╭─[typescript/tests/cases/compiler/jsFileCompilationConstructorOverloadSyntax.ts:2:16]
+  × Expected function body
+   ╭─[typescript/tests/cases/compiler/jsFileCompilationConstructorOverloadSyntax.ts:2:14]
  1 │ class A {
  2 │   constructor();
-   ·                ─
+   ·              ──
  3 │ }
    ╰────
+  help: Add a function body (`{}`).
 
   × Unexpected token
    ╭─[typescript/tests/cases/compiler/jsFileCompilationEnumSyntax.ts:1:1]
@@ -7211,11 +7212,12 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ·        ─
    ╰────
 
-  × Unexpected token
-   ╭─[typescript/tests/cases/compiler/jsFileCompilationFunctionOverloadSyntax.ts:1:15]
+  × Expected function body
+   ╭─[typescript/tests/cases/compiler/jsFileCompilationFunctionOverloadSyntax.ts:1:1]
  1 │ function foo();
-   ·               ─
+   · ──────────────
    ╰────
+  help: Add a function body (`{}`).
 
   × TS(8002): 'import ... =' can only be used in TypeScript files.
    ╭─[typescript/tests/cases/compiler/jsFileCompilationImportEqualsSyntax.ts:1:1]
@@ -7231,13 +7233,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: Try inserting a semicolon here
 
-  × Unexpected token
-   ╭─[typescript/tests/cases/compiler/jsFileCompilationMethodOverloadSyntax.ts:2:8]
+  × Expected function body
+   ╭─[typescript/tests/cases/compiler/jsFileCompilationMethodOverloadSyntax.ts:2:6]
  1 │ class A {
  2 │   foo();
-   ·        ─
+   ·      ──
  3 │ }
    ╰────
+  help: Add a function body (`{}`).
 
   × Expected a semicolon or an implicit semicolon after a statement, but found none
    ╭─[typescript/tests/cases/compiler/jsFileCompilationModuleSyntax.ts:1:10]
@@ -7268,11 +7271,12 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: No modifiers are allowed here.
 
-  × Unexpected token
-   ╭─[typescript/tests/cases/compiler/jsFileCompilationReturnTypeSyntaxOfFunction.ts:1:13]
+  × Expected function body
+   ╭─[typescript/tests/cases/compiler/jsFileCompilationReturnTypeSyntaxOfFunction.ts:1:1]
  1 │ function F(): number { }
-   ·             ─
+   · ────────────
    ╰────
+  help: Add a function body (`{}`).
 
   × Expected a semicolon or an implicit semicolon after a statement, but found none
    ╭─[typescript/tests/cases/compiler/jsFileCompilationTypeAliasSyntax.ts:1:5]