fix(es/parser): Emit an error for multiple constructors with body (#4031)

crates/swc_ecma_parser/src/error.rs

@@ -169,6 +169,7 @@ pub enum SyntaxError {
     PrivateNameModifier(JsWord),
     ReadOnlyMethod,
     GeneratorConstructor,
+    DuplicateConstructor,
     TsBindingPatCannotBeOptional,
     SuperCallOptional,
 
@@ -422,6 +423,7 @@ impl SyntaxError {
             SyntaxError::PropertyNamedConstructor => {
                 "Classes may not have a non-static field named 'constructor'".into()
             }
+            SyntaxError::DuplicateConstructor => "A class can only have one constructor".into(),
             SyntaxError::PrivateNameModifier(modifier) => format!(
                 "'{}' modifier cannot be used with a private identifier",
                 modifier

crates/swc_ecma_parser/src/parser/class_and_fn.rs

@@ -316,6 +316,7 @@ impl<'a, I: Tokens> Parser<I> {
 
     fn parse_class_body(&mut self) -> PResult<Vec<ClassMember>> {
         let mut elems = vec![];
+        let mut has_constructor_with_body = false;
         while !eof!(self) && !is!(self, '}') {
             if eat_exact!(self, ';') {
                 let span = self.input.prev_span();
@@ -328,7 +329,22 @@ impl<'a, I: Tokens> Parser<I> {
                 allow_direct_super: true,
                 ..self.ctx()
             });
-            elems.push(p.parse_class_member()?);
+            let elem = p.parse_class_member()?;
+
+            if !p.ctx().in_declare {
+                if let ClassMember::Constructor(Constructor {
+                    body: Some(..),
+                    span,
+                    ..
+                }) = elem
+                {
+                    if has_constructor_with_body {
+                        p.emit_err(span, SyntaxError::DuplicateConstructor);
+                    }
+                    has_constructor_with_body = true;
+                }
+            }
+            elems.push(elem);
         }
         Ok(elems)
     }
@@ -706,6 +722,14 @@ impl<'a, I: Tokens> Parser<I> {
                 let body: Option<_> =
                     self.parse_fn_body(false, false, params.is_simple_parameter_list())?;
 
+                if body.is_none() {
+                    for param in params.iter() {
+                        if param.is_ts_param_prop() {
+                            self.emit_err(param.span(), SyntaxError::TS2369)
+                        }
+                    }
+                }
+
                 if self.syntax().typescript() && body.is_none() {
                     // Declare constructors cannot have assignment pattern in parameters
                     for p in &params {

crates/swc_ecma_parser/tests/typescript-errors/class/override-parameter-property/input.ts.stderr

@@ -10,3 +10,9 @@
  3 | constructor(override public v: string)
    :                      ^^^^^^^^^^^^^^^^
    `----
+
+  x A parameter property is only allowed in a constructor implementation
+   ,-[$DIR/tests/typescript-errors/class/override-parameter-property/input.ts:3:3]
+ 3 | constructor(override public v: string)
+   :             ^^^^^^^^^^^^^^^^^^^^^^^^^
+   `----

crates/swc_node_bundler/tests/pass/deno-001/full/input/textproto/mod.ts

@@ -24,7 +24,6 @@ function charCode(s: string): number {
 
 export class TextProtoReader {
   constructor(readonly r: BufReader) { }
-  constructor(readonly r: BufReader) { }
 
   /** readLine() reads a single line from the TextProtoReader,
    * eliding the final \n or \r\n from the returned string.

crates/swc_node_bundler/tests/pass/deno-001/full/output/entry.js

@@ -354,9 +354,6 @@ function charCode(s) {
     return s.charCodeAt(0);
 }
 class TextProtoReader {
-    constructor(r){
-        this.r = r;
-    }
     constructor(r){
         this.r = r;
     }