feat(es/parser): Disallow tagged tpl in optional chaining (#7515)

Author: g-plane

crates/swc_ecma_parser/src/error.rs

@@ -195,6 +195,7 @@ pub enum SyntaxError {
     TsBindingPatCannotBeOptional,
     SuperCallOptional,
     OptChainCannotFollowConstructorCall,
+    TaggedTplInOptChain,
 
     TrailingCommaInsideImport,
 
@@ -470,6 +471,9 @@ impl SyntaxError {
             SyntaxError::OptChainCannotFollowConstructorCall => {
                 "Constructor in/after an optional chaining is not allowed.".into()
             }
+            SyntaxError::TaggedTplInOptChain => {
+                "Tagged template literal is not allowed in optional chain.".into()
+            }
             SyntaxError::TsInvalidParamPropPat => {
                 "Typescript parameter property must be an identifier or assignment pattern".into()
             }

crates/swc_ecma_parser/src/parser/expr.rs

@@ -1060,6 +1060,11 @@ impl<I: Tokens> Parser<I> {
         let tpl = Box::new(self.parse_tpl(true)?);
 
         let span = span!(self, tagged_tpl_start);
+
+        if tag.is_opt_chain() {
+            self.emit_err(span, SyntaxError::TaggedTplInOptChain);
+        }
+
         Ok(TaggedTpl {
             span,
             tag,

crates/swc_ecma_parser/tests/errors/optional-chaining/tagged-template.js

@@ -0,0 +1 @@
+a?.b``

crates/swc_ecma_parser/tests/errors/optional-chaining/tagged-template.js.swc-stderr

@@ -0,0 +1,6 @@
+
+  x Tagged template literal is not allowed in optional chain.
+   ,-[$DIR/tests/errors/optional-chaining/tagged-template.js:1:1]
+ 1 | a?.b``
+   : ^^^^^^
+   `----