Combine const and enum handlers

[jdesrosiers]

Currently if we have multiple const or enum keywords apply to the same location we get multiple error messages.

{
  "allOf": [
    { "enum": ["a", "b", "c"] },
    { "enum": ["a", "b"] },
    { "const": "a" }
  ]
}

We'll multiple messages

• Expected one of "a", "b", or "c"
• Expected one of "a" or "b"
• Expected exactly "a"

Most of this is noise for the user and can be reduced to just,

• Expected exactly "a"

For this task, I want to combine the error handlers for enum and const and reduce these keywords to a single const or enum message.

[Sam-61s]

Hii @jdesrosiers,
I'll combine the const and enum error handlers to compute the intersection of all allowed values and produce a single message—using const if the intersection is one value, otherwise enum with the intersection.
Assign it to me, I'd like to raise a PR with proposed fix

[jdesrosiers]

I just assigned you another one. Let's stick to one at a time.

[ShivaGupta-14]

@jdesrosiers

My Understanding

• const keyword specifies exactly one allowed value (e.g., "a")
• enum keyword specifies an array of allowed values (e.g., ["a", "b", "c"])
• const is semantically equivalent to enum with a single element -> use const-style message for better clarity

Multiple const/enum from allOf -> separate messages, Instead of multiple errors, compute intersection of all allowed values across failing locations, single message with tightest constraint.

Proposed Solution
create constAndEnum.js handler: compute intersection of all const and enum value sets, generate one message based on result size (1 value -> const-style, multiple -> enum-style).

could you please assign this to me? Thanks :)

[jdesrosiers]

Go ahead @ShivaGupta-14

[ShivaGupta-14]

Hi @jdesrosiers!

Thanks for assigning, I have a question, could you please guide me?

edge case: what should happen if const and enum constraints have no intersection?

{
  "allOf": [
    { "enum": ["a", "b"] },
    { "const": "c" }
  ]
}

Intersection: empty

My approach:

• report message: "Contradicting schema: these constraints cannot be satisfied together"
• schemaLocations: all conflicting locations

am I going in right direction?

[jdesrosiers]

Good question. See the changes I just merged for the type error handler for an example. It's equivalent to the boolean schema false, so we use the same message.