Skip to content

Fix CancellationToken parameter ordering and name collision in v3 OperationCompiler #341

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
Copilot wants to merge 2 commits into
base: repo-assist/feat-cancellationtoken-issue-212-2026-03-23-448c1cde90ec7d95
Choose a base branch
from
Draft

Fix CancellationToken parameter ordering and name collision in v3 OperationCompiler #341

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
e16554d
Initial plan
Copilot Mar 23, 2026
0395a26
fix: insert CT between required and optional params; generate unique …
Copilot Mar 23, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
74 changes: 46 additions & 28 deletions src/SwaggerProvider.DesignTime/v3/OperationCompiler.fs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,
let (|NoMediaType|_|)(content: IDictionary<string, OpenApiMediaType>) =
if isNull content || content.Count = 0 then Some() else None

let payloadMime, parameters =
let payloadMime, parameters, ctArgIndex =
/// handles de-duplicating Swagger parameter names if the same parameter name
/// appears in multiple locations in a given operation definition.
let uniqueParamName usedNames (param: IOpenApiParameter) =
Expand Down Expand Up @@ -147,18 +147,15 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,

let payloadTy = bodyFormatAndParam |> Option.map fst |> Option.defaultValue NoData

let orderedParameters =
let required, optional =
[ yield! openApiParameters
if bodyFormatAndParam.IsSome then
yield bodyFormatAndParam.Value |> snd ]
|> List.distinctBy(fun op -> op.Name, op.In)
|> List.partition(_.Required)
let requiredOpenApiParams, optionalOpenApiParams =
[ yield! openApiParameters
if bodyFormatAndParam.IsSome then
yield bodyFormatAndParam.Value |> snd ]
|> List.distinctBy(fun op -> op.Name, op.In)
|> List.partition(_.Required)

List.append required optional

let providedParameters =
((Set.empty, []), orderedParameters)
let buildProvidedParameters usedNames (paramList: IOpenApiParameter list) =
((usedNames, []), paramList)
||> List.fold(fun (names, parameters) current ->
let names, paramName = uniqueParamName names current

Expand All @@ -173,21 +170,37 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,
ProvidedParameter(paramName, paramType, false, paramDefaultValue)

(names, providedParam :: parameters))
|> snd
// because we built up our list in reverse order with the fold,
// reverse it again so that all required properties come first
|> List.rev
|> fun (finalNames, ps) -> finalNames, List.rev ps

let namesAfterRequired, requiredProvidedParams =
buildProvidedParameters Set.empty requiredOpenApiParams

let _, optionalProvidedParams =
buildProvidedParameters namesAfterRequired optionalOpenApiParams

let parameters =
let ctArgIndex, parameters =
if includeCancellationToken then
let ctParam =
ProvidedParameter("cancellationToken", typeof<Threading.CancellationToken>)
// Collect all used param names to generate a unique CT parameter name
let usedNames =
(requiredProvidedParams @ optionalProvidedParams)
|> List.map(fun p -> p.Name)
|> Set.ofList

let rec findUniqueName candidate n =
if Set.contains candidate usedNames then
findUniqueName $"cancellationToken{n}" (n + 1)
else
candidate

providedParameters @ [ ctParam ]
let ctName = findUniqueName "cancellationToken" 1
let ctParam = ProvidedParameter(ctName, typeof<Threading.CancellationToken>)
// CT is inserted after required params so it never follows optional params
let ctArgIndex = List.length requiredProvidedParams
ctArgIndex, requiredProvidedParams @ [ ctParam ] @ optionalProvidedParams
else
providedParameters
-1, requiredProvidedParams @ optionalProvidedParams

payloadTy.ToMediaType(), parameters
payloadTy.ToMediaType(), parameters, ctArgIndex

// find the inner type value
let retMimeAndTy =
Expand Down Expand Up @@ -273,16 +286,21 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,
// Locates parameters matching the arguments
let mutable payloadExp = None

// When the CancellationToken overload is generated, CancellationToken is always appended last.
// Extract it by position to avoid name-collision issues and invalid Expr.Coerce
// on a struct type (which generates an invalid castclass IL instruction).
// When the CancellationToken overload is generated, CT is inserted at ctArgIndex
// (after required params, before optional params). Extract it by that known index
// to avoid name-collision issues and invalid Expr.Coerce on a struct type.
let apiArgs, ct =
let allArgs = List.tail args // skip `this`

if includeCancellationToken then
match List.rev allArgs with
| ctArg :: revApiArgs -> List.rev revApiArgs, Expr.Cast<Threading.CancellationToken>(ctArg)
| [] -> failwith "Expected CancellationToken argument but argument list was empty"
let ctArg = List.item ctArgIndex allArgs

let apiArgs =
allArgs
|> List.indexed
|> List.choose(fun (i, a) -> if i = ctArgIndex then None else Some a)

apiArgs, Expr.Cast<Threading.CancellationToken>(ctArg)
else
allArgs, <@ Threading.CancellationToken.None @>

Expand Down
Loading