bake: report a server module that JSC rejects as a build error instead of aborting the dev server

src/ast/lib.rs

@@ -2847,6 +2847,9 @@ impl Source {
         col: u64,
     ) -> Option<usize> {
         use bun_core::strings::{CodepointIterator, Cursor};
+        if line == start_line && col == start_col {
+            return Some(0);
+        }
         let iter_ = CodepointIterator::init(source_contents);
         let mut iter = Cursor::default();
 

src/runtime/bake/BakeSourceProvider.cpp

@@ -15,6 +15,7 @@
 #include "JavaScriptCore/JSModuleRecord.h"
 #include "JavaScriptCore/JSString.h"
 #include "JavaScriptCore/JSModuleNamespaceObject.h"
+#include "JavaScriptCore/ParserError.h"
 #include "ImportMetaObject.h"
 #include <wtf/text/MakeString.h>
 
@@ -81,26 +82,30 @@ extern "C" JSC::EncodedJSValue BakeLoadModuleByKey(JSC::JSGlobalObject* global,
   return JSC::JSValue::encode(promise);
 }
 
-extern "C" JSC::EncodedJSValue BakeLoadServerHmrPatch(GlobalObject* global, BunString source) {
-  JSC::VM&vm = global->vm();
-  auto scope = DECLARE_THROW_SCOPE(vm);
-
-  String string = "bake://server.patch.js"_s;
-  JSC::SourceOrigin origin = JSC::SourceOrigin(WTF::URL(string));
-  JSC::SourceCode sourceCode = JSC::SourceCode(SourceProvider::create(
-    global,
-    source.transferToWTFString(),
-    origin,
-    WTF::move(string),
-    WTF::TextPosition(),
-    JSC::SourceProviderSourceType::Program
-  ));
-
-  JSC::JSValue result = vm.interpreter.executeProgram(sourceCode, global, global);
-  RETURN_IF_EXCEPTION(scope, {});
+// Returns true when JSC's parser rejects `source`. `errorLine` and `errorColumn` are then 0-based.
+extern "C" bool BakeFindServerCodeSyntaxError(JSC::JSGlobalObject* global, BunString source, uint32_t* errorLine, uint32_t* errorColumn, BunString* errorMessage) {
+  auto& vm = JSC::getVM(global);
+  JSC::SourceCode sourceCode = JSC::makeSource(source.transferToWTFString(), JSC::SourceOrigin(), JSC::SourceTaintedOrigin::Untainted);
+
+  JSC::ParserError error;
+  if (JSC::checkSyntax(vm, sourceCode, error)) return false;
+
+  String message;
+  if (error.type() == JSC::ParserError::SyntaxError) {
+    message = error.message();
+  } else if (error.type() == JSC::ParserError::StackOverflow) {
+    // The parser gives this one no message.
+    message = "Maximum call stack size exceeded."_s;
+  } else {
+    return false;
+  }
 
-  RELEASE_ASSERT(result);
-  return JSC::JSValue::encode(result);
+  int offset = error.token().m_startPosition.offset;
+  JSC::LineColumn position = sourceCode.provider()->lineColumnInTextForOffset(offset < 0 ? 0 : offset);
+  *errorLine = position.line;
+  *errorColumn = position.column;
+  *errorMessage = Bun::toStringRef(message);
+  return true;
 }
 
 extern "C" JSC::EncodedJSValue BakeLoadServerHmrPatchWithSourceMap(GlobalObject* global, BunString source, const char* sourceMapJSONPtr, size_t sourceMapJSONLength) {
@@ -112,7 +117,6 @@ extern "C" JSC::EncodedJSValue BakeLoadServerHmrPatchWithSourceMap(GlobalObject*
 
   // Use DevServerSourceProvider with the source map JSON
   auto provider = DevServerSourceProvider::create(
-    global,
     source.transferToWTFString(),
     sourceMapJSONPtr,
     sourceMapJSONLength,
@@ -128,6 +132,8 @@ extern "C" JSC::EncodedJSValue BakeLoadServerHmrPatchWithSourceMap(GlobalObject*
   RETURN_IF_EXCEPTION(scope, {});
 
   RELEASE_ASSERT(result);
+  // A chunk that did not load must not take the source map of the code that runs.
+  provider->registerSourceMap(global);
   return JSC::JSValue::encode(result);
 }
 

src/runtime/bake/DevServerSourceProvider.h

@@ -16,7 +16,6 @@ extern "C" void Bun__removeDevServerSourceProvider(void* bun_vm, DevServerSource
 class DevServerSourceProvider final : public JSC::StringSourceProvider {
 public:
     static Ref<DevServerSourceProvider> create(
-        JSC::JSGlobalObject* globalObject,
         const String& source,
         const char* sourceMapJSONPtr,
         size_t sourceMapJSONLength,
@@ -25,13 +24,16 @@ class DevServerSourceProvider final : public JSC::StringSourceProvider {
         const TextPosition& startPosition,
         JSC::SourceProviderSourceType sourceType)
     {
-        auto provider = adoptRef(*new DevServerSourceProvider(source, sourceMapJSONPtr, sourceMapJSONLength, sourceOrigin, WTF::move(sourceURL), startPosition, sourceType));
-        auto* zigGlobalObject = uncheckedDowncast<::Zig::GlobalObject>(globalObject);
-        auto specifier = Bun::toString(provider->sourceURL());
-        provider->m_bunVM = zigGlobalObject->bunVM();
-        provider->m_specifier = specifier;
-        Bun__addDevServerSourceProvider(provider->m_bunVM, provider.ptr(), &specifier);
-        return provider;
+        return adoptRef(*new DevServerSourceProvider(source, sourceMapJSONPtr, sourceMapJSONLength, sourceOrigin, WTF::move(sourceURL), startPosition, sourceType));
+    }
+
+    // Stack traces then remap through this provider. It takes the place of the provider that had the same URL.
+    void registerSourceMap(JSC::JSGlobalObject* globalObject)
+    {
+        ASSERT(!m_bunVM);
+        m_bunVM = uncheckedDowncast<::Zig::GlobalObject>(globalObject)->bunVM();
+        m_specifier = Bun::toString(sourceURL());
+        Bun__addDevServerSourceProvider(m_bunVM, this, &m_specifier);
     }
 
     MiCString sourceMapJSON() const
@@ -67,7 +69,7 @@ class DevServerSourceProvider final : public JSC::StringSourceProvider {
     }
 
     MiString m_sourceMapJSON;
-    // The Rust VirtualMachine, captured at creation. Not the GC-allocated
+    // The Rust VirtualMachine, captured by registerSourceMap. Not the GC-allocated
     // Zig::GlobalObject: this destructor runs from JSC sweep, by which point
     // the global object cell may already have been swept.
     void* m_bunVM { nullptr };