Typescript: Poll: Name a compiler option for including `undefined` when a property resolves to an index signature

[RyanCavanaugh]

We need a name for the option described in #13778

The exact behavior that this flag would enable is, briefly:

• Read expressions of the form expr[i] will now be T | undefined where T is the index signature type
• Read expressions of the form expr.prop will now be T | undefined where T is the index signature type if an index signature on expr exists but not a declared property named prop
• string and number index signatures are both subjected to this treatment
• Write expressions expr[i] = v and expr.prop = v are unaffected
• Type expressions TypeName[number] and TypeName["prop"] are unaffected

Good candidate flag names should follow these rules and goals:

• Do not start with strict since this flag would not get turned on by the global --strict setting
• Follow an existing convention (see the list at (https://aka.ms/tsconfig.json)
• Convey the intent of the flag along with its behavior, somehow
• Avoid problematic terms (e.g. do not reference mental illnesses)

This is an open-ended approval voting issue. Rules:

• Use 👍 reaction on as many as you like
  
  
  
  • Top-upvoted options will be given the most consideration
  
  
  • This is an advisory vote; final say is still up to the TypeScript team
  
  
• You may propose new options; comments must be of exactly the form `--proposedOptionName`
  
  
  
  • Follow the above guidance - no --strictFoo!
  
  
• No discussion here; discuss in #13778. Non-option comments will be deleted
• Sharing this link on social media is encouraged!

I will seed this with some of the names suggested at our last meeting. We may also cull options that aren't receiving a lot of votes to help keep the comment count manageable.

[RyanCavanaugh]

--pedanticIndexSignatures

[RyanCavanaugh]

--noUncheckedIndexedAccess

[RyanCavanaugh]

--undefinedIndexSignatures

[RyanCavanaugh]

--skepticalIndexAccesses

[RyanCavanaugh]

--noImplicitBounds

[orta]

--rigorousIndexAccess

[danvk]

--carefulIndexAccess

[jack-williams]

--partialIndexedAccess

[awinograd]

--maybeIndexAccess

[OliverJAsh]

--indexNullChecks (like --strictNullChecks but for index access)

[kirillgroshkov]

--safeIndexAccess

[danvk]

--soundIndexedAccess

[patrickkunka]

--uncertainIndexAccess

Personally I feel the name should highlight the aspect of uncertainty introduced here, rather than the aspect of strictness.

[thw0rted]

--includeUndefinedInIndexSignatures

[thw0rted]

--includeUndefinedInIndexAccess

[alex-okrushko]

--noUncheckedIndexedAccess

I think this one nails it, however I'd adjust it to --noUncheckedIndexAccess (uncheck-ed and index-ed it a feels a bit too much of -ed).

[zeusdeux]

--checkIndexedAccess

[RyanCavanaugh]

We have a winner 🥇

[johnnyreilly]

Are you rolling with --noUncheckedIndexedAccess or @alex-okrushko's suggested tweak of --noUncheckedIndexAccess?