feat: allow int64 custom scalars

[pavelnikolov]

Allow int64 custom scalars.

Closes #305

[Copilot]

Pull request overview

Adds support for passing large integer literals through to custom scalar unmarshaling by deserializing integer literals as int64 when they don’t fit in 32-bit, while preserving existing int32 behavior for 32-bit-range values.

Changes:

• Update integer literal deserialization to parse as 64-bit and return int64 when outside 32-bit range.
• Extend input coercion for int32 targets to also accept int64 values.
• Add a regression test covering custom Int64 scalar input alongside built-in Int range validation behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
ast/value.go	Parses integer literals with 64-bit precision and returns int64 for out-of-32-bit-range values.
internal/exec/packer/packer.go	Adds int64 → int32 coercion for packing into int32 Go targets.
issue_305_test.go	Introduces test coverage for large integer literal behavior with a custom Int64 scalar and built-in Int validation.

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[Copilot]

The test scalar’s UnmarshalGraphQL only accepts int64. With the current deserialization behavior, integer literals within 32-bit range are still provided as int32, so this scalar would reject valid Int64 inputs like custom(hash: 123). Consider accepting both int32 and int64 (casting int32 up) so the test scalar matches real-world usage and doesn’t encode an overly strict/unintuitive contract.

Suggested change

	value, ok := input.(int64)
	if !ok {
	return fmt.Errorf("Int64 expects int64 got %T", input)
	}
	u.Value = value
	return nil
	switch v := input.(type) {
	case int64:
	u.Value = v
	return nil
	case int32:
	u.Value = int64(v)
	return nil
	default:
	return fmt.Errorf("Int64 expects int64 got %T", input)
	}

[Copilot]

UnmarshalInput now explicitly accepts int64 for reflect.Int32, but integer literals can also deserialize to int64 when used in a GraphQL Float position (GraphQL allows Int literals for Float). The reflect.Float64 branch currently only coerces int32/int, so a large integer literal (or a variable value) arriving as int64 will fail with "incompatible type". Please add int64 handling in the reflect.Float64 coercion path (and consider tests for Float arguments with large integer literals).