schema_for! on HashMap and BTreeMap no longer generates field information for values

[snoyberg]

Sorry for the confusing title, allow me to demonstrate. I bisected this issue down to the commit:

e470075

You can see the issue with this code:

use cosmwasm_schema::cw_serde;
use std::collections::BTreeMap;

#[cw_serde]
struct HasMap {
    map_field: BTreeMap<String, u32>,
    normal_field: u32,
}

fn main() {
    let schema = cosmwasm_schema::schema_for!(HasMap);
    println!("{schema:#?}");
}

With cosmwasm-schema version 2.0.2, the output I receive is:

RootSchema {
    meta_schema: Some(
        "http://json-schema.org/draft-07/schema#",
    ),
    schema: SchemaObject {
        metadata: Some(
            Metadata {
                id: None,
                title: Some(
                    "HasMap",
                ),
                description: None,
                default: None,
                deprecated: false,
                read_only: false,
                write_only: false,
                examples: [],
            },
        ),
        instance_type: Some(
            Single(
                Object,
            ),
        ),
        format: None,
        enum_values: None,
        const_value: None,
        subschemas: None,
        number: None,
        string: None,
        array: None,
        object: Some(
            ObjectValidation {
                max_properties: None,
                min_properties: None,
                required: {
                    "map_field",
                    "normal_field",
                },
                properties: {
                    "map_field": Object(
                        SchemaObject {
                            metadata: None,
                            instance_type: Some(
                                Single(
                                    Object,
                                ),
                            ),
                            format: None,
                            enum_values: None,
                            const_value: None,
                            subschemas: None,
                            number: None,
                            string: None,
                            array: None,
                            object: Some(
                                ObjectValidation {
                                    max_properties: None,
                                    min_properties: None,
                                    required: {},
                                    properties: {},
                                    pattern_properties: {},
                                    additional_properties: Some(
                                        Object(
                                            SchemaObject {
                                                metadata: None,
                                                instance_type: Some(
                                                    Single(
                                                        Integer,
                                                    ),
                                                ),
                                                format: Some(
                                                    "uint32",
                                                ),
                                                enum_values: None,
                                                const_value: None,
                                                subschemas: None,
                                                number: Some(
                                                    NumberValidation {
                                                        multiple_of: None,
                                                        maximum: None,
                                                        exclusive_maximum: None,
                                                        minimum: Some(
                                                            0.0,
                                                        ),
                                                        exclusive_minimum: None,
                                                    },
                                                ),
                                                string: None,
                                                array: None,
                                                object: None,
                                                reference: None,
                                                extensions: {},
                                            },
                                        ),
                                    ),
                                    property_names: None,
                                },
                            ),
                            reference: None,
                            extensions: {},
                        },
                    ),
                    "normal_field": Object(
                        SchemaObject {
                            metadata: None,
                            instance_type: Some(
                                Single(
                                    Integer,
                                ),
                            ),
                            format: Some(
                                "uint32",
                            ),
                            enum_values: None,
                            const_value: None,
                            subschemas: None,
                            number: Some(
                                NumberValidation {
                                    multiple_of: None,
                                    maximum: None,
                                    exclusive_maximum: None,
                                    minimum: Some(
                                        0.0,
                                    ),
                                    exclusive_minimum: None,
                                },
                            ),
                            string: None,
                            array: None,
                            object: None,
                            reference: None,
                            extensions: {},
                        },
                    ),
                },
                pattern_properties: {},
                additional_properties: Some(
                    Bool(
                        false,
                    ),
                ),
                property_names: None,
            },
        ),
        reference: None,
        extensions: {},
    },
    definitions: {},
}

But with version 2.1.2, instead I get:

RootSchema {
    meta_schema: Some(
        "http://json-schema.org/draft-07/schema#",
    ),
    schema: SchemaObject {
        metadata: Some(
            Metadata {
                id: None,
                title: Some(
                    "HasMap",
                ),
                description: None,
                default: None,
                deprecated: false,
                read_only: false,
                write_only: false,
                examples: [],
            },
        ),
        instance_type: Some(
            Single(
                Object,
            ),
        ),
        format: None,
        enum_values: None,
        const_value: None,
        subschemas: None,
        number: None,
        string: None,
        array: None,
        object: Some(
            ObjectValidation {
                max_properties: None,
                min_properties: None,
                required: {
                    "map_field",
                    "normal_field",
                },
                properties: {
                    "map_field": Object(
                        SchemaObject {
                            metadata: None,
                            instance_type: Some(
                                Single(
                                    Object,
                                ),
                            ),
                            format: None,
                            enum_values: None,
                            const_value: None,
                            subschemas: None,
                            number: None,
                            string: None,
                            array: None,
                            object: Some(
                                ObjectValidation {
                                    max_properties: None,
                                    min_properties: None,
                                    required: {},
                                    properties: {},
                                    pattern_properties: {},
                                    additional_properties: Some(
                                        Bool(
                                            false,
                                        ),
                                    ),
                                    property_names: None,
                                },
                            ),
                            reference: None,
                            extensions: {},
                        },
                    ),
                    "normal_field": Object(
                        SchemaObject {
                            metadata: None,
                            instance_type: Some(
                                Single(
                                    Integer,
                                ),
                            ),
                            format: Some(
                                "uint32",
                            ),
                            enum_values: None,
                            const_value: None,
                            subschemas: None,
                            number: Some(
                                NumberValidation {
                                    multiple_of: None,
                                    maximum: None,
                                    exclusive_maximum: None,
                                    minimum: Some(
                                        0.0,
                                    ),
                                    exclusive_minimum: None,
                                },
                            ),
                            string: None,
                            array: None,
                            object: None,
                            reference: None,
                            extensions: {},
                        },
                    ),
                },
                pattern_properties: {},
                additional_properties: Some(
                    Bool(
                        false,
                    ),
                ),
                property_names: None,
            },
        ),
        reference: None,
        extensions: {},
    },
    definitions: {},
}

Since that's a lot of content, here's the diff between the two:

<                                         Object(
<                                             SchemaObject {
<                                                 metadata: None,
<                                                 instance_type: Some(
<                                                     Single(
<                                                         Integer,
<                                                     ),
<                                                 ),
<                                                 format: Some(
<                                                     "uint32",
<                                                 ),
<                                                 enum_values: None,
<                                                 const_value: None,
<                                                 subschemas: None,
<                                                 number: Some(
<                                                     NumberValidation {
<                                                         multiple_of: None,
<                                                         maximum: None,
<                                                         exclusive_maximum: None,
<                                                         minimum: Some(
<                                                             0.0,
<                                                         ),
<                                                         exclusive_minimum: None,
<                                                     },
<                                                 ),
<                                                 string: None,
<                                                 array: None,
<                                                 object: None,
<                                                 reference: None,
<                                                 extensions: {},
<                                             },
---
>                                         Bool(
>                                             false,

Note that the old version correctly generated schema information indicating that the contents of the field are an Object with uint32s as values. Without this, the generated schemas are missing that information, which ultimately (in our use case) leads to incorrectly generated TypeScript types.

[aumetra]

That is.. an interesting effect of that visitor. It definitely shouldn't have that kind of effect. The reason for the visitor was to prevent the TypeScript type generator to add a field to capture potential additional properties that weren't covered by the schema without adding #[serde(deny_unknown_fields)] (which had undesired issues for users; see #2019)

This might be a weird interation between map types and the additional_properties field? Not sure. I'll check that..

[aumetra]

Actually, I have a potential solution. I'll just need to inspect generated TypeScript types to check for regressions.

The type of the value of the map is encoded in the additionalProperties, so if we simply set it to false if it's unset, it shouldn't complain?

And yeah, this points at some lack of coverage in our tests. After creating such a patch and regenerating all schemas, there is no difference.

[snoyberg]

I don't know much about the JSON schema standard, so I'm not sure of the right outcome here. I appreciate you looking into it. I'd be happy to test out any changes against our codebase if it would be helpful.