Editorial: Add new convention for abstract ops that don't throw

[bterlson]

As discussed in #253. Thoughts on this? I personally find this easier to read.

I've also gone ahead and added ! to a few places where it is needed (mostly ToString invocations). The next biggest class of calls that can't fail are to Type and min/max/friends. Since these can never throw by definition I wonder if it's worth adding ! in these types of cases. I'm leaning toward not on the grounds that Type is a short-hand and min/max/etc. are math functions and so neither actually returns a completion record... Thoughts?

[ljharb]

should CreateDataProperty have a ? or a ! in front of it?

[ljharb]

add prefix on [[Delete]], and remove this line?

[ljharb]

k sorry, i'll stop - we should probably check all the Let _status_ and CreateDataProperty usages and that will cover the majority of my comments :-)

[domenic]

This change is great, and @ljharb's thorough review is great too. We should merge. We can incrementally fix remaining issues later; I kind of expect @anba will have a way of doing so in an automated fashion...

[ljharb]

Agreed, I don't think any of my comments should block this change, just cleanups that might be missed later if not caught now :-) this is a huge improvement imo.

[bterlson]

This PR isn't trying to be exhaustive :) Landing this now, please send PRs for all the others as you come across them!

Committed as 166ab2b (rebased, fixed merge conflicts).

[anba]

I kind of expect @anba will have a way of doing so in an automated fashion...

Fixing all remaining issues will be a tedious work. I think it's only fair the proponents of the ! prefix get a chance to improve their commit statistics. Here's an incomplete (!) list what needs to be changed. 😝

• All calls to: IsAccessorDescriptor, IsDataDescriptor, IsGenericDescriptor, ObjectCreate, ToBoolean, IsCallable, IsConstructor, SameValue, SameValueZero, SameValueNonNumber, IsPropertyKey, CreateIterResultObject, CreateBuiltinFunction, CreateRealm, CreateIntrinsics, SetRealmGlobalObject, NewGlobalEnvironment, NewDeclarativeEnvironment, NewObjectEnvironment, NewFunctionEnvironment, NewModuleEnvironment, GetThisEnvironment, GetNewTarget, GetGlobalObject, EnqueueJob, AddRestrictedFunctionProperties, CanonicalNumericIndexString, IsInteger, CreateArrayFromList, CreateListIterator, FunctionAllocate, FunctionInitialize, FunctionCreate, GeneratorFunctionCreate, MakeConstructor, MakeClassConstructor, MakeMethod, SetFunctionName, StringCreate, CreateUnmappedArgumentsObject, CreateMappedArgumentsObject, IntegerIndexedObjectCreate, ModuleNamespaceCreate, ...

Reference type:

• All calls to: GetBase, GetReferencedName, IsStrictReference, HasPrimitiveBase, IsPropertyReference, IsUnresolvableReference, IsSuperReference, GetThisValue

Declarative Environment Record:

• All calls to: HasBinding, CreateMutableBinding, CreateImmutableBinding, InitializeBinding, DeleteBinding

Other operations:

• ToObject in Reference::GetValue and Reference::PutValue
• CreateDataProperty in FromPropertyDescriptor
• ToString in "ToString Applied to the Number Type"
• ToNumber in CanonicalNumericIndexString
• ArrayCreate in CreateArrayFromList
• CreateDataProperty in CreateArrayFromList
• CreateDataProperty in CreateIterResultObject
• CreateMethodProperty in CreateListIterator
• DefinePropertyOrThrow in MakeConstructor
• ...