Bug 1617972. Add a table that stores the exception type of DOM errors. r=peterv

The callsite in DOMIntersectionObserver did end up throwing a RangeError, as the
spec requires, because in the end we just used the exception code to determine
the kind of exception to throw, but was misleading about what it was doing.

Differential Revision: https://phabricator.services.mozilla.com/D64175

--HG--
extra : moz-landing-system : lando

dom/base/DOMIntersectionObserver.cpp

@@ -118,7 +118,7 @@ already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
     observer->mThresholds.SetCapacity(thresholds.Length());
     for (const auto& thresh : thresholds) {
       if (thresh < 0.0 || thresh > 1.0) {
-        aRv.ThrowTypeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
+        aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
         return nullptr;
       }
       observer->mThresholds.AppendElement(thresh);
@@ -127,7 +127,7 @@ already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
   } else {
     double thresh = aOptions.mThreshold.GetAsDouble();
     if (thresh < 0.0 || thresh > 1.0) {
-      aRv.ThrowTypeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
+      aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
       return nullptr;
     }
     observer->mThresholds.AppendElement(thresh);

dom/bindings/ErrorResult.h

@@ -31,6 +31,7 @@
 #include <utility>
 
 #include "js/GCAnnotations.h"
+#include "js/ErrorReport.h"
 #include "js/Value.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
@@ -76,6 +77,13 @@ bool constexpr ErrorFormatHasContext[] = {
 #undef MSG_DEF
 };
 
+// Table of the kinds of exceptions error messages will produce.
+JSExnType constexpr ErrorExceptionType[] = {
+#define MSG_DEF(_name, _argc, _has_context, _exn, _str) _exn,
+#include "mozilla/dom/Errors.msg"
+#undef MSG_DEF
+};
+
 uint16_t GetErrorArgCount(const ErrNum aErrorNumber);
 
 namespace binding_detail {
@@ -289,6 +297,8 @@ class TErrorResult {
   template <dom::ErrNum errorNumber, typename... Ts>
   void MOZ_MUST_RETURN_FROM_CALLER_IF_THIS_IS_ARG
   ThrowTypeError(Ts&&... messageArgs) {
+    static_assert(dom::ErrorExceptionType[errorNumber] == JSEXN_TYPEERR,
+                  "Throwing a non-TypeError via ThrowTypeError");
     ThrowErrorWithMessage<errorNumber>(NS_ERROR_INTERNAL_ERRORRESULT_TYPEERROR,
                                        std::forward<Ts>(messageArgs)...);
   }
@@ -311,6 +321,8 @@ class TErrorResult {
   template <dom::ErrNum errorNumber, typename... Ts>
   void MOZ_MUST_RETURN_FROM_CALLER_IF_THIS_IS_ARG
   ThrowRangeError(Ts&&... messageArgs) {
+    static_assert(dom::ErrorExceptionType[errorNumber] == JSEXN_RANGEERR,
+                  "Throwing a non-RangeError via ThrowRangeError");
     ThrowErrorWithMessage<errorNumber>(NS_ERROR_INTERNAL_ERRORRESULT_RANGEERROR,
                                        std::forward<Ts>(messageArgs)...);
   }