From 606a11949ee0fecbb3cae68b0191814b6efb5cb1 Mon Sep 17 00:00:00 2001
From: Simon Zünd <szuend@chromium.org>
Date: Mon, 23 Mar 2026 11:43:12 +0000
Subject: [PATCH] [inspector] Don't emit scriptFailedToParse on setBreakpoint

Setting breakpoints triggers re-compilation if V8 hasn't compiled the
script yet or the GC evicted it.

If the top-level compilation fails, the inspector receives another
'scriptFailedToParse' event.

The "real" fix would be to forward a "CLEAR_EXCEPTION" bit into
'CompileTopLevel' in V8.

For now, we prevent setting breakpoints on broken scripts, they can't be
run in any case.

Drive-by: Catch exceptions when setting breakpoints in case there are
other ways where we re-enter V8 (e.g. via the regex).

R=bmeurer@chromium.org

Bug: 493631402
Change-Id: I18ec510a8288fd2a4bc44921ba538613ee8e1201
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7690996
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#105967}
---

diff --git a/src/inspector/v8-debugger-agent-impl.cc b/src/inspector/v8-debugger-agent-impl.cc
index 2e78b58..b39dfea 100644
--- a/src/inspector/v8-debugger-agent-impl.cc
+++ b/src/inspector/v8-debugger-agent-impl.cc
@@ -446,7 +446,7 @@
   std::vector<std::unique_ptr<V8DebuggerScript>> compiledScripts =
       m_debugger->getCompiledScripts(m_session->contextGroupId(), this);
   for (auto& script : compiledScripts) {
-    didParseSource(std::move(script), true);
+    didParseSource(std::move(script));
   }
 
   m_breakpointsActive = m_state->booleanProperty(
@@ -1073,6 +1073,7 @@
   ScriptsMap::iterator scriptIterator = m_scripts.find(scriptId);
   if (scriptIterator == m_scripts.end()) return nullptr;
   V8DebuggerScript* script = scriptIterator->second.get();
+  if (script->hadCompileError()) return nullptr;
 
   v8::debug::BreakpointId debuggerBreakpointId;
   v8::debug::Location location(lineNumber, columnNumber);
@@ -1083,6 +1084,7 @@
 
   {
     v8::Context::Scope contextScope(inspected->context());
+    v8::TryCatch tryCatch(m_isolate);
     if (!script->setBreakpoint(condition, &location, &debuggerBreakpointId)) {
       return nullptr;
     }
@@ -1956,9 +1958,9 @@
 }  // namespace
 
 void V8DebuggerAgentImpl::didParseSource(
-    std::unique_ptr<V8DebuggerScript> script, bool success) {
+    std::unique_ptr<V8DebuggerScript> script) {
   v8::HandleScope handles(m_isolate);
-  if (!success) {
+  if (script->hadCompileError()) {
     String16 scriptSource = script->source(0);
     script->setSourceURL(findSourceURL(scriptSource, false));
     script->setSourceMappingURL(findSourceMapURL(scriptSource, false));
@@ -2025,7 +2027,7 @@
           ? stack->buildInspectorObjectImpl(m_debugger, 0)
           : nullptr;
 
-  if (!success) {
+  if (scriptRef->hadCompileError()) {
     m_frontend.scriptFailedToParse(
         scriptId, scriptURL, scriptRef->startLine(), scriptRef->startColumn(),
         scriptRef->endLine(), scriptRef->endColumn(), contextId,
diff --git a/src/inspector/v8-debugger-agent-impl.h b/src/inspector/v8-debugger-agent-impl.h
index 7c81ced..c71e9ab 100644
--- a/src/inspector/v8-debugger-agent-impl.h
+++ b/src/inspector/v8-debugger-agent-impl.h
@@ -182,7 +182,7 @@
                 v8::debug::ExceptionType exceptionType, bool isUncaught,
                 v8::debug::BreakReasons breakReasons);
   void didContinue();
-  void didParseSource(std::unique_ptr<V8DebuggerScript>, bool success);
+  void didParseSource(std::unique_ptr<V8DebuggerScript>);
 
   bool isFunctionBlackboxed(const String16& scriptId,
                             const v8::debug::Location& start,
diff --git a/src/inspector/v8-debugger-script.cc b/src/inspector/v8-debugger-script.cc
index 5d65d7a..05f8107 100644
--- a/src/inspector/v8-debugger-script.cc
+++ b/src/inspector/v8-debugger-script.cc
@@ -42,13 +42,15 @@
 
 V8DebuggerScript::V8DebuggerScript(v8::Isolate* isolate,
                                    v8::Local<v8::debug::Script> script,
-                                   bool isLiveEdit, V8DebuggerAgentImpl* agent,
+                                   bool hadCompileError, bool isLiveEdit,
+                                   V8DebuggerAgentImpl* agent,
                                    V8InspectorClient* client)
     : m_id(String16::fromInteger(script->Id())),
       m_url(GetScriptURL(isolate, script, client)),
       m_isolate(isolate),
       m_embedderName(GetScriptName(isolate, script, client)),
       m_agent(agent),
+      m_hadCompileError(hadCompileError),
       m_isLiveEdit(isLiveEdit) {
   Initialize(script);
 }
diff --git a/src/inspector/v8-debugger-script.h b/src/inspector/v8-debugger-script.h
index d8f5e1d..107b870 100644
--- a/src/inspector/v8-debugger-script.h
+++ b/src/inspector/v8-debugger-script.h
@@ -53,8 +53,8 @@
   enum class Language { JavaScript, WebAssembly };
 
   V8DebuggerScript(v8::Isolate* isolate, v8::Local<v8::debug::Script> script,
-                   bool isLiveEdit, V8DebuggerAgentImpl* agent,
-                   V8InspectorClient* client);
+                   bool hadCompileError, bool isLiveEdit,
+                   V8DebuggerAgentImpl* agent, V8InspectorClient* client);
   ~V8DebuggerScript() = default;
   V8DebuggerScript(const V8DebuggerScript&) = delete;
   V8DebuggerScript& operator=(const V8DebuggerScript&) = delete;
@@ -76,6 +76,7 @@
   int endColumn() const { return m_endColumn; }
   int codeOffset() const;
   int executionContextId() const { return m_executionContextId; }
+  bool hadCompileError() const { return m_hadCompileError; }
   bool isLiveEdit() const { return m_isLiveEdit; }
   bool isModule() const { return m_isModule; }
   int length() const;
@@ -132,6 +133,7 @@
   String16 m_sourceMappingURL;
   mutable String16 m_buildId;
   Language m_language;
+  bool m_hadCompileError = false;
   bool m_isLiveEdit = false;
   bool m_isModule = false;
   mutable String16 m_hash;
diff --git a/src/inspector/v8-debugger.cc b/src/inspector/v8-debugger.cc
index 72e5f49..faa2463 100644
--- a/src/inspector/v8-debugger.cc
+++ b/src/inspector/v8-debugger.cc
@@ -169,7 +169,7 @@
       if (m_inspector->contextGroupId(contextId) != contextGroupId) continue;
     }
     result.push_back(std::make_unique<V8DebuggerScript>(
-        m_isolate, script, false, agent, m_inspector->client()));
+        m_isolate, script, false, false, agent, m_inspector->client()));
   }
   return result;
 }
@@ -604,10 +604,8 @@
        client](V8InspectorSessionImpl* session) {
         auto agent = session->debuggerAgent();
         if (!agent->enabled()) return;
-        agent->didParseSource(
-            std::make_unique<V8DebuggerScript>(isolate, script, is_live_edited,
-                                               agent, client),
-            !has_compile_error);
+        agent->didParseSource(std::make_unique<V8DebuggerScript>(
+            isolate, script, has_compile_error, is_live_edited, agent, client));
       });
 }
 
diff --git a/test/inspector/debugger/set-breakpoint-by-url-in-broken-script-expected.txt b/test/inspector/debugger/set-breakpoint-by-url-in-broken-script-expected.txt
new file mode 100644
index 0000000..e0f9392
--- /dev/null
+++ b/test/inspector/debugger/set-breakpoint-by-url-in-broken-script-expected.txt
@@ -0,0 +1,21 @@
+Check that setBreakpointByUrl in a broken script doesn't trigger scriptFailedToParse
+{
+    method : Debugger.scriptFailedToParse
+    params : {
+        buildId : 
+        embedderName : foo.js
+        endColumn : 1
+        endLine : 0
+        executionContextId : <executionContextId>
+        hasSourceURL : false
+        hash : 021fb596db81e6d02bf3d2586ee3981fe519f275c0ac9ca76bbcf2ebb4097d96
+        isModule : false
+        length : 1
+        scriptId : <scriptId>
+        scriptLanguage : JavaScript
+        sourceMapURL : 
+        startColumn : 0
+        startLine : 0
+        url : foo.js
+    }
+}
diff --git a/test/inspector/debugger/set-breakpoint-by-url-in-broken-script.js b/test/inspector/debugger/set-breakpoint-by-url-in-broken-script.js
new file mode 100644