6 files changed, 401 insertions, 69 deletions

diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 6d6eacec2..8cb3e5802 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -69,7 +69,6 @@
 #include "js/Proxy.h"
 #include "js/SliceBudget.h"
 #include "js/StructuredClone.h"
-#include "js/UniquePtr.h"
 #include "js/Utility.h"
 #include "vm/AsyncFunction.h"
 #include "vm/DateObject.h"
@@ -6300,7 +6299,7 @@ JSErrorReport::freeLinebuf()
 }
 
 JSString*
-JSErrorReport::newMessageString(JSContext* cx)
+JSErrorBase::newMessageString(JSContext* cx)
 {
     if (!message_)
         return cx->runtime()->emptyString;
@@ -6309,7 +6308,7 @@ JSErrorReport::newMessageString(JSContext* cx)
 }
 
 void
-JSErrorReport::freeMessage()
+JSErrorBase::freeMessage()
 {
     if (ownsMessage_) {
         js_free((void*)message_.get());
@@ -6318,6 +6317,132 @@ JSErrorReport::freeMessage()
     message_ = JS::ConstUTF8CharsZ();
 }
 
+JSErrorNotes::JSErrorNotes()
+  : notes_()
+{}
+
+JSErrorNotes::~JSErrorNotes()
+{
+}
+
+static UniquePtr<JSErrorNotes::Note>
+CreateErrorNoteVA(JSContext* cx,
+                  const char* filename, unsigned lineno, unsigned column,
+                  JSErrorCallback errorCallback, void* userRef,
+                  const unsigned errorNumber,
+                  ErrorArgumentsType argumentsType, va_list ap)
+{
+    auto note = MakeUnique<JSErrorNotes::Note>();
+    if (!note)
+        return nullptr;
+
+    note->errorNumber = errorNumber;
+    note->filename = filename;
+    note->lineno = lineno;
+    note->column = column;
+
+    if (!ExpandErrorArgumentsVA(cx, errorCallback, userRef, errorNumber,
+                                nullptr, argumentsType, note.get(), ap)) {
+        return nullptr;
+    }
+
+    return note;
+}
+
+bool
+JSErrorNotes::addNoteASCII(JSContext* cx,
+                           const char* filename, unsigned lineno, unsigned column,
+                           JSErrorCallback errorCallback, void* userRef,
+                           const unsigned errorNumber, ...)
+{
+    va_list ap;
+    va_start(ap, errorNumber);
+    auto note = CreateErrorNoteVA(cx, filename, lineno, column, errorCallback, userRef,
+                                  errorNumber, ArgumentsAreASCII, ap);
+    va_end(ap);
+
+    if (!note)
+        return false;
+    if (!notes_.append(Move(note)))
+        return false;
+    return true;
+}
+
+bool
+JSErrorNotes::addNoteLatin1(JSContext* cx,
+                            const char* filename, unsigned lineno, unsigned column,
+                            JSErrorCallback errorCallback, void* userRef,
+                            const unsigned errorNumber, ...)
+{
+    va_list ap;
+    va_start(ap, errorNumber);
+    auto note = CreateErrorNoteVA(cx, filename, lineno, column, errorCallback, userRef,
+                                  errorNumber, ArgumentsAreLatin1, ap);
+    va_end(ap);
+
+    if (!note)
+        return false;
+    if (!notes_.append(Move(note)))
+        return false;
+    return true;
+}
+
+bool
+JSErrorNotes::addNoteUTF8(JSContext* cx,
+                          const char* filename, unsigned lineno, unsigned column,
+                          JSErrorCallback errorCallback, void* userRef,
+                          const unsigned errorNumber, ...)
+{
+    va_list ap;
+    va_start(ap, errorNumber);
+    auto note = CreateErrorNoteVA(cx, filename, lineno, column, errorCallback, userRef,
+                                  errorNumber, ArgumentsAreUTF8, ap);
+    va_end(ap);
+
+    if (!note)
+        return false;
+    if (!notes_.append(Move(note)))
+        return false;
+    return true;
+}
+
+size_t
+JSErrorNotes::length()
+{
+    return notes_.length();
+}
+
+UniquePtr<JSErrorNotes>
+JSErrorNotes::copy(JSContext* cx)
+{
+    auto copiedNotes = MakeUnique<JSErrorNotes>();
+    if (!copiedNotes)
+        return nullptr;
+
+    for (auto&& note : *this) {
+        js::UniquePtr<JSErrorNotes::Note> copied(CopyErrorNote(cx, note.get()));
+        if (!copied)
+            return nullptr;
+
+        if (!copiedNotes->notes_.append(Move(copied)))
+            return nullptr;
+    }
+
+    return copiedNotes;
+}
+
+JSErrorNotes::iterator
+JSErrorNotes::begin()
+{
+    return iterator(notes_.begin());
+}
+
+JSErrorNotes::iterator
+JSErrorNotes::end()
+{
+    return iterator(notes_.end());
+}
+
 JS_PUBLIC_API(bool)
 JS_ThrowStopIteration(JSContext* cx)
 {
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 3f65dad34..99100620a 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -18,6 +18,7 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/Variant.h"
 
+#include <iterator>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -36,6 +37,7 @@
 #include "js/Realm.h"
 #include "js/RootingAPI.h"
 #include "js/TracingAPI.h"
+#include "js/UniquePtr.h"
 #include "js/Utility.h"
 #include "js/Value.h"
 #include "js/Vector.h"
@@ -5362,14 +5364,130 @@ JS_ReportOutOfMemory(JSContext* cx);
 extern JS_PUBLIC_API(void)
 JS_ReportAllocationOverflow(JSContext* cx);
 
-class JSErrorReport
+/**
+ * Base class that implements parts shared by JSErrorReport and
+ * JSErrorNotes::Note.
+ */
+class JSErrorBase
 {
     // The (default) error message.
     // If ownsMessage_ is true, the it is freed in destructor.
     JS::ConstUTF8CharsZ message_;
 
+  public:
+    JSErrorBase()
+      : filename(nullptr), lineno(0), column(0),
+        errorNumber(0),
+        ownsMessage_(false)
+    {}
+
+    ~JSErrorBase() {
+        freeMessage();
+    }
+
+    // Source file name, URL, etc., or null.
+    const char* filename;
+
+    // Source line number.
+    unsigned lineno;
+
+    // Zero-based column index in line.
+    unsigned column;
+
+    // the error number, e.g. see js.msg.
+    unsigned errorNumber;
+
+  private:
+    bool ownsMessage_ : 1;
+
+  public:
+    const JS::ConstUTF8CharsZ message() const {
+        return message_;
+    }
+
+    void initOwnedMessage(const char* messageArg) {
+        initBorrowedMessage(messageArg);
+        ownsMessage_ = true;
+    }
+    void initBorrowedMessage(const char* messageArg) {
+        MOZ_ASSERT(!message_);
+        message_ = JS::ConstUTF8CharsZ(messageArg, strlen(messageArg));
+    }
+
+    JSString* newMessageString(JSContext* cx);
+
+  private:
+    void freeMessage();
+};
+
+/**
+ * Notes associated with JSErrorReport.
+ */
+class JSErrorNotes
+{
+  public:
+    class Note : public JSErrorBase
+    {};
+
+  private:
+    // Stores pointers to each note.
+    js::Vector<js::UniquePtr<Note>, 1, js::SystemAllocPolicy> notes_;
+
+  public:
+    JSErrorNotes();
+    ~JSErrorNotes();
+
+    // Add an note to the given position.
+    bool addNoteASCII(JSContext* cx,
+                      const char* filename, unsigned lineno, unsigned column,
+                      JSErrorCallback errorCallback, void* userRef,
+                      const unsigned errorNumber, ...);
+    bool addNoteLatin1(JSContext* cx,
+                       const char* filename, unsigned lineno, unsigned column,
+                       JSErrorCallback errorCallback, void* userRef,
+                       const unsigned errorNumber, ...);
+    bool addNoteUTF8(JSContext* cx,
+                     const char* filename, unsigned lineno, unsigned column,
+                     JSErrorCallback errorCallback, void* userRef,
+                     const unsigned errorNumber, ...);
+
+    size_t length();
+
+    // Create a deep copy of notes.
+    js::UniquePtr<JSErrorNotes> copy(JSContext* cx);
+
+    class iterator : public std::iterator<std::input_iterator_tag, js::UniquePtr<Note>>
+    {
+        js::UniquePtr<Note>* note_;
+      public:
+        explicit iterator(js::UniquePtr<Note>* note = nullptr) : note_(note)
+        {}
+
+        bool operator==(iterator other) const {
+            return note_ == other.note_;
+        }
+        bool operator!=(iterator other) const {
+            return !(*this == other);
+        }
+        iterator& operator++() {
+            note_++;
+            return *this;
+        }
+        reference operator*() {
+            return *note_;
+        }
+    };
+    iterator begin();
+    iterator end();
+};
+
+/**
+ * Describes a single error or warning that occurs in the execution of script.
+ */
+class JSErrorReport : public JSErrorBase
+{
     // Offending source line without final '\n'.
-    // If ownsLinebuf__ is true, the buffer is freed in destructor.
+    // If ownsLinebuf_ is true, the buffer is freed in destructor.
     const char16_t* linebuf_;
 
     // Number of chars in linebuf_. Does not include trailing '\0'.
@@ -5381,28 +5499,29 @@ class JSErrorReport
   public:
     JSErrorReport()
       : linebuf_(nullptr), linebufLength_(0), tokenOffset_(0),
-        filename(nullptr), lineno(0), column(0),
-        flags(0), errorNumber(0),
-        exnType(0), isMuted(false),
-        ownsLinebuf_(false), ownsMessage_(false)
+        notes(nullptr),
+        flags(0), exnType(0), isMuted(false),
+        ownsLinebuf_(false)
     {}
 
     ~JSErrorReport() {
         freeLinebuf();
-        freeMessage();
     }
 
-    const char*     filename;      /* source file name, URL, etc., or null */
-    unsigned        lineno;         /* source line number */
-    unsigned        column;         /* zero-based column index in line */
-    unsigned        flags;          /* error/warning, etc. */
-    unsigned        errorNumber;    /* the error number, e.g. see js.msg */
-    int16_t         exnType;        /* One of the JSExnType constants */
-    bool            isMuted : 1;    /* See the comment in ReadOnlyCompileOptions. */
+    // Associated notes, or nullptr if there's no note.
+    js::UniquePtr<JSErrorNotes> notes;
+
+    // error/warning, etc.
+    unsigned flags;
+
+    // One of the JSExnType constants.
+    int16_t exnType;
+
+    // See the comment in ReadOnlyCompileOptions.
+    bool isMuted : 1;
 
   private:
     bool ownsLinebuf_ : 1;
-    bool ownsMessage_ : 1;
 
   public:
     const char16_t* linebuf() const {
@@ -5414,29 +5533,16 @@ class JSErrorReport
     size_t tokenOffset() const {
         return tokenOffset_;
     }
-    void initOwnedLinebuf(const char16_t* linebufArg, size_t linebufLengthArg, size_t tokenOffsetArg) {
+    void initOwnedLinebuf(const char16_t* linebufArg, size_t linebufLengthArg,
+                          size_t tokenOffsetArg) {
         initBorrowedLinebuf(linebufArg, linebufLengthArg, tokenOffsetArg);
         ownsLinebuf_ = true;
     }
-    void initBorrowedLinebuf(const char16_t* linebufArg, size_t linebufLengthArg, size_t tokenOffsetArg);
-    void freeLinebuf();
-
-    const JS::ConstUTF8CharsZ message() const {
-        return message_;
-    }
-
-    void initOwnedMessage(const char* messageArg) {
-        initBorrowedMessage(messageArg);
-        ownsMessage_ = true;
-    }
-    void initBorrowedMessage(const char* messageArg) {
-        MOZ_ASSERT(!message_);
-        message_ = JS::ConstUTF8CharsZ(messageArg, strlen(messageArg));
-    }
+    void initBorrowedLinebuf(const char16_t* linebufArg, size_t linebufLengthArg,
+                             size_t tokenOffsetArg);
 
-    JSString* newMessageString(JSContext* cx);
-
-    void freeMessage();
+  private:
+    void freeLinebuf();
 };
 
 /*
diff --git a/js/src/jscntxt.cpp b/js/src/jscntxt.cpp
index 31d62332d..4e34c0e48 100644
--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -557,6 +557,18 @@ class MOZ_RAII AutoMessageArgs
     }
 };
 
+static void
+SetExnType(JSErrorReport* reportp, int16_t exnType)
+{
+    reportp->exnType = exnType;
+}
+
+static void
+SetExnType(JSErrorNotes::Note* notep, int16_t exnType)
+{
+    // Do nothing for JSErrorNotes::Note.
+}
+
 /*
  * The arguments from ap need to be packaged up into an array and stored
  * into the report struct.
@@ -568,12 +580,13 @@ class MOZ_RAII AutoMessageArgs
  *
  * Returns true if the expansion succeeds (can fail if out of memory).
  */
+template <typename T>
 bool
-js::ExpandErrorArgumentsVA(ExclusiveContext* cx, JSErrorCallback callback,
+ExpandErrorArgumentsHelper(ExclusiveContext* cx, JSErrorCallback callback,
                            void* userRef, const unsigned errorNumber,
                            const char16_t** messageArgs,
                            ErrorArgumentsType argumentsType,
-                           JSErrorReport* reportp, va_list ap)
+                           T* reportp, va_list ap)
 {
     const JSErrorFormatString* efs;
 
@@ -586,7 +599,7 @@ js::ExpandErrorArgumentsVA(ExclusiveContext* cx, JSErrorCallback callback,
     }
 
     if (efs) {
-        reportp->exnType = efs->exnType;
+        SetExnType(reportp, efs->exnType);
 
         MOZ_ASSERT_IF(argumentsType == ArgumentsAreASCII, JS::StringIsASCII(efs->format));
 
@@ -670,6 +683,28 @@ js::ExpandErrorArgumentsVA(ExclusiveContext* cx, JSErrorCallback callback,
 }
 
 bool
+js::ExpandErrorArgumentsVA(ExclusiveContext* cx, JSErrorCallback callback,
+                           void* userRef, const unsigned errorNumber,
+                           const char16_t** messageArgs,
+                           ErrorArgumentsType argumentsType,
+                           JSErrorReport* reportp, va_list ap)
+{
+    return ExpandErrorArgumentsHelper(cx, callback, userRef, errorNumber,
+                                      messageArgs, argumentsType, reportp, ap);
+}
+
+bool
+js::ExpandErrorArgumentsVA(JSContext* cx, JSErrorCallback callback,
+                           void* userRef, const unsigned errorNumber,
+                           const char16_t** messageArgs,
+                           ErrorArgumentsType argumentsType,
+                           JSErrorNotes::Note* notep, va_list ap)
+{
+    return ExpandErrorArgumentsHelper(cx, callback, userRef, errorNumber,
+                                      messageArgs, argumentsType, notep, ap);
+}
+
+bool
 js::ReportErrorNumberVA(JSContext* cx, unsigned flags, JSErrorCallback callback,
                         void* userRef, const unsigned errorNumber,
                         ErrorArgumentsType argumentsType, va_list ap)
diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index 0a2841242..c1e676f68 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -621,6 +621,13 @@ ExpandErrorArgumentsVA(ExclusiveContext* cx, JSErrorCallback callback,
                        ErrorArgumentsType argumentsType,
                        JSErrorReport* reportp, va_list ap);
 
+extern bool
+ExpandErrorArgumentsVA(JSContext* cx, JSErrorCallback callback,
+                       void* userRef, const unsigned errorNumber,
+                       const char16_t** messageArgs,
+                       ErrorArgumentsType argumentsType,
+                       JSErrorNotes::Note* notep, va_list ap);
+
 /* |callee| requires a usage string provided by JS_DefineFunctionsWithHelp. */
 extern void
 ReportUsageErrorASCII(JSContext* cx, HandleObject callee, const char* msg);
diff --git a/js/src/jsexn.cpp b/js/src/jsexn.cpp
index 102e6fb34..b07d118b9 100644
--- a/js/src/jsexn.cpp
+++ b/js/src/jsexn.cpp
@@ -201,28 +201,77 @@ ErrorObject::classes[JSEXN_ERROR_LIMIT] = {
     IMPLEMENT_ERROR_CLASS(RuntimeError)
 };
 
-JSErrorReport*
-js::CopyErrorReport(JSContext* cx, JSErrorReport* report)
+size_t
+ExtraMallocSize(JSErrorReport* report)
+{
+    if (report->linebuf())
+        return (report->linebufLength() + 1) * sizeof(char16_t);
+
+    return 0;
+}
+
+size_t
+ExtraMallocSize(JSErrorNotes::Note* note)
+{
+    return 0;
+}
+
+bool
+CopyExtraData(JSContext* cx, uint8_t** cursor, JSErrorReport* copy, JSErrorReport* report)
+{
+    if (report->linebuf()) {
+        size_t linebufSize = (report->linebufLength() + 1) * sizeof(char16_t);
+        const char16_t* linebufCopy = (const char16_t*)(*cursor);
+        js_memcpy(*cursor, report->linebuf(), linebufSize);
+        *cursor += linebufSize;
+        copy->initBorrowedLinebuf(linebufCopy, report->linebufLength(), report->tokenOffset());
+    }
+
+    /* Copy non-pointer members. */
+    copy->isMuted = report->isMuted;
+    copy->exnType = report->exnType;
+
+    /* Note that this is before it gets flagged with JSREPORT_EXCEPTION */
+    copy->flags = report->flags;
+
+    /* Deep copy notes. */
+    if (report->notes) {
+        auto copiedNotes = report->notes->copy(cx);
+        if (!copiedNotes)
+            return false;
+        copy->notes = Move(copiedNotes);
+    } else {
+        copy->notes.reset(nullptr);
+    }
+
+    return true;
+}
+
+bool
+CopyExtraData(JSContext* cx, uint8_t** cursor, JSErrorNotes::Note* copy, JSErrorNotes::Note* report)
+{
+    return true;
+}
+
+template <typename T>
+static T*
+CopyErrorHelper(JSContext* cx, T* report)
 {
     /*
-     * We use a single malloc block to make a deep copy of JSErrorReport with
+     * We use a single malloc block to make a deep copy of JSErrorReport or
+     * JSErrorNotes::Note, except JSErrorNotes linked from JSErrorReport with
      * the following layout:
-     *   JSErrorReport
+     *   JSErrorReport or JSErrorNotes::Note
      *   char array with characters for message_
-     *   char16_t array with characters for linebuf
      *   char array with characters for filename
+     *   char16_t array with characters for linebuf (only for JSErrorReport)
      * Such layout together with the properties enforced by the following
      * asserts does not need any extra alignment padding.
      */
-    JS_STATIC_ASSERT(sizeof(JSErrorReport) % sizeof(const char*) == 0);
+    JS_STATIC_ASSERT(sizeof(T) % sizeof(const char*) == 0);
     JS_STATIC_ASSERT(sizeof(const char*) % sizeof(char16_t) == 0);
 
-#define JS_CHARS_SIZE(chars) ((js_strlen(chars) + 1) * sizeof(char16_t))
-
     size_t filenameSize = report->filename ? strlen(report->filename) + 1 : 0;
-    size_t linebufSize = 0;
-    if (report->linebuf())
-        linebufSize = (report->linebufLength() + 1) * sizeof(char16_t);
     size_t messageSize = 0;
     if (report->message())
         messageSize = strlen(report->message().c_str()) + 1;
@@ -231,13 +280,13 @@ js::CopyErrorReport(JSContext* cx, JSErrorReport* report)
      * The mallocSize can not overflow since it represents the sum of the
      * sizes of already allocated objects.
      */
-    size_t mallocSize = sizeof(JSErrorReport) + messageSize + linebufSize + filenameSize;
+    size_t mallocSize = sizeof(T) + messageSize + filenameSize + ExtraMallocSize(report);
     uint8_t* cursor = cx->pod_calloc<uint8_t>(mallocSize);
     if (!cursor)
         return nullptr;
 
-    JSErrorReport* copy = (JSErrorReport*)cursor;
-    cursor += sizeof(JSErrorReport);
+    T* copy = new (cursor) T();
+    cursor += sizeof(T);
 
     if (report->message()) {
         copy->initBorrowedMessage((const char*)cursor);
@@ -245,33 +294,40 @@ js::CopyErrorReport(JSContext* cx, JSErrorReport* report)
         cursor += messageSize;
     }
 
-    if (report->linebuf()) {
-        const char16_t* linebufCopy = (const char16_t*)cursor;
-        js_memcpy(cursor, report->linebuf(), linebufSize);
-        cursor += linebufSize;
-        copy->initBorrowedLinebuf(linebufCopy, report->linebufLength(), report->tokenOffset());
-    }
-
     if (report->filename) {
         copy->filename = (const char*)cursor;
         js_memcpy(cursor, report->filename, filenameSize);
+        cursor += filenameSize;
+    }
+
+    if (!CopyExtraData(cx, &cursor, copy, report)) {
+        /* js_delete calls destructor for T and js_free for pod_calloc. */
+        js_delete(copy);
+        return nullptr;
     }
-    MOZ_ASSERT(cursor + filenameSize == (uint8_t*)copy + mallocSize);
+
+    MOZ_ASSERT(cursor == (uint8_t*)copy + mallocSize);
 
     /* Copy non-pointer members. */
-    copy->isMuted = report->isMuted;
     copy->lineno = report->lineno;
     copy->column = report->column;
     copy->errorNumber = report->errorNumber;
-    copy->exnType = report->exnType;
 
-    /* Note that this is before it gets flagged with JSREPORT_EXCEPTION */
-    copy->flags = report->flags;
-
-#undef JS_CHARS_SIZE
     return copy;
 }
 
+JSErrorNotes::Note*
+js::CopyErrorNote(JSContext* cx, JSErrorNotes::Note* note)
+{
+    return CopyErrorHelper(cx, note);
+}
+
+JSErrorReport*
+js::CopyErrorReport(JSContext* cx, JSErrorReport* report)
+{
+    return CopyErrorHelper(cx, report);
+}
+
 struct SuppressErrorsGuard
 {
     JSContext* cx;
@@ -322,7 +378,7 @@ exn_finalize(FreeOp* fop, JSObject* obj)
 {
     MOZ_ASSERT(fop->maybeOffMainThread());
     if (JSErrorReport* report = obj->as<ErrorObject>().getErrorReport())
-        fop->free_(report);
+        fop->delete_(report);
 }
 
 JSErrorReport*
diff --git a/js/src/jsexn.h b/js/src/jsexn.h
index ae6335209..1698bb2e9 100644
--- a/js/src/jsexn.h
+++ b/js/src/jsexn.h
@@ -18,6 +18,9 @@
 namespace js {
 class ErrorObject;
 
+JSErrorNotes::Note*
+CopyErrorNote(JSContext* cx, JSErrorNotes::Note* note);
+
 JSErrorReport*
 CopyErrorReport(JSContext* cx, JSErrorReport* report);