Summary

This PR adds support for OpenAPI parameters with no type specified (schema: {}). Previously, these parameters would cause "any type parameter not supported" errors. Now they are represented as Go any type.

Motivation

OpenAPI allows parameters to have schemas with no type field specified, which means the parameter can be of any type. ogen was rejecting these with an error, making it impossible to work with specs that use this pattern (common in legacy APIs or APIs with dynamic parameter types).

Implementation

Core Changes (5 files, 21 lines changed):

1. gen/_template/uri/decode.tmpl - Added IsAny case to decode URI strings into Go any type
2. gen/_template/uri/encode.tmpl - Added IsAny case with nil check, uses fmt.Sprint() for encoding
3. gen/gen_parameters.go - Removed error case that rejected any type parameters
4. gen/ir/type.go - Added feature check to return "any" for URI contexts vs "jx.Raw" for JSON bodies
5. README.md - Documented the feature

Design Decisions:

• Go any type: More semantically accurate than forcing to string - if the schema says "any", the Go type should be any
• Client encoding: Uses fmt.Sprint() for flexibility (allows passing strings, ints, bools, etc.)
• Context differentiation: JSON bodies use jx.Raw, URI parameters use any (different serialization contexts)
• No smart parsing: Keeps implementation simple - server receives string, client can send any value that fmt.Sprint can handle

Test Coverage

• _testdata/positive/any_parameters.json - Comprehensive OpenAPI test spec
• internal/integration/any_parameters_test.go - Full integration test covering:
  • Required parameters (path, query, header, cookie)
  • Optional parameters
  • Array parameters
  • Nil handling

Breaking Changes

None - this is purely additive. Existing code continues to work unchanged.

Example Usage

Server side:

func (h *Handler) AnyParams(ctx context.Context, params api.AnyParamsParams) (*api.AnyParamsOK, error) {
    // Type assert the any value
    queryStr := params.Query.(string)
    
    if params.Filter != nil {
        filterStr := params.Filter.(string)
        // Use optional filter...
    }
    
    return &api.AnyParamsOK{Message: "ok"}, nil
}

Client side:

// Can pass different types - all will be encoded via fmt.Sprint()
client.AnyParams(ctx, api.AnyParamsParams{
    Query: "search text",      // string
    ID: 123,                   // int
    Filter: api.OptAny(true),  // bool
})