Add use counter for var redeclarations of catch bindings

Bug: v8:10516
Change-Id: I0a75b32ca4b90dc5a6c2f2f3ec66b183dc3ff99e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2191411
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67724}

include/v8.h

@@ -8449,6 +8449,7 @@ class V8_EXPORT Isolate {
     kInvalidatedStringLengthOverflowLookupChainProtector = 104,
     kInvalidatedTypedArraySpeciesLookupChainProtector = 105,
     kWasmSimdOpcodes = 106,
+    kVarRedeclaredCatchBinding = 107,
 
     // If you add new values here, you'll also need to update Chromium's:
     // web_feature.mojom, use_counter_callback.cc, and enums.xml. V8 changes to

src/ast/scopes.cc

@@ -1138,7 +1138,8 @@ Variable* Scope::NewTemporary(const AstRawString* name,
   return var;
 }
 
-Declaration* DeclarationScope::CheckConflictingVarDeclarations() {
+Declaration* DeclarationScope::CheckConflictingVarDeclarations(
+    bool* allowed_catch_binding_var_redeclaration) {
   if (has_checked_syntax_) return nullptr;
   for (Declaration* decl : decls_) {
     // Lexical vs lexical conflicts within the same scope have already been
@@ -1152,11 +1153,12 @@ Declaration* DeclarationScope::CheckConflictingVarDeclarations() {
       // Iterate through all scopes until the declaration scope.
       do {
         // There is a conflict if there exists a non-VAR binding.
+        Variable* other_var = current->LookupLocal(decl->var()->raw_name());
         if (current->is_catch_scope()) {
+          *allowed_catch_binding_var_redeclaration |= other_var != nullptr;
           current = current->outer_scope();
           continue;
         }
-        Variable* other_var = current->LookupLocal(decl->var()->raw_name());
         if (other_var != nullptr) {
           DCHECK(IsLexicalVariableMode(other_var->mode()));
           return decl;

src/ast/scopes.h

@@ -909,7 +909,8 @@ class V8_EXPORT_PRIVATE DeclarationScope : public Scope {
   // Check if the scope has conflicting var
   // declarations, i.e. a var declaration that has been hoisted from a nested
   // scope over a let binding of the same name.
-  Declaration* CheckConflictingVarDeclarations();
+  Declaration* CheckConflictingVarDeclarations(
+      bool* allowed_catch_binding_var_redeclaration);
 
   void set_has_checked_syntax(bool has_checked_syntax) {
     has_checked_syntax_ = has_checked_syntax;

src/parsing/parser-base.h

@@ -1247,7 +1247,12 @@ class ParserBase {
   // hoisted over such a scope.
   void CheckConflictingVarDeclarations(DeclarationScope* scope) {
     if (has_error()) return;
-    Declaration* decl = scope->CheckConflictingVarDeclarations();
+    bool allowed_catch_binding_var_redeclaration = false;
+    Declaration* decl = scope->CheckConflictingVarDeclarations(
+        &allowed_catch_binding_var_redeclaration);
+    if (allowed_catch_binding_var_redeclaration) {
+      impl()->CountUsage(v8::Isolate::kVarRedeclaredCatchBinding);
+    }
     if (decl != nullptr) {
       // In ES6, conflicting variable bindings are early errors.
       const AstRawString* name = decl->var()->raw_name();