Request context is lost

[ferdypruis]

In oauth2.Transport.RoundTrip the given request is cloned so it may be changed (auth header added), as dictated by the Roundtripper-contract. But this clone does not include the request context.

This can easily be fixed.

Index: transport.go
IDEA additional info:
<+>UTF-8
===================================================================
--- transport.go	(revision 9fd604954f58d391cab0f7f49affb0a6aa864086)
+++ transport.go	(date 1606751247213)
@@ -80,6 +80,7 @@
 	// shallow copy of the struct
 	r2 := new(http.Request)
 	*r2 = *r
+	r2 = r2.WithContext(r.Context())
 	// deep copy of the Header
 	r2.Header = make(http.Header, len(r.Header))
 	for k, s := range r.Header {

Current versions of Go have a http.Request.Clone receiver which clones even more fields, which might serve as inspiration.

[willmo]

Doesn't *r2 = *r copy the field .ctx? (Sorry if I'm missing something.)

There are a lot of other context-related bugs and confusions though (#262 #324 #388 #564...).

[ferdypruis]

Doesn't *r2 = *r copy the field .ctx? (Sorry if I'm missing something.)

Because the ctx field is unexported it is not accessible and therefor not copied.

[willmo]

It works for me: https://go.dev/play/p/Sdjef2JUQ1S . And see also https://go.dev/doc/go1#unexported .

I think using .Clone instead makes sense though.

[ferdypruis]

You have me confused here. I was convinced I had the issue of my context not being copied and fixed it with this change.
But you are right.

Your test works and the Go specification clearly states;

Behind the scenes the unexported fields will be assigned and copied just as if they were exported, but the client code will never be aware of them.

I can not reproduce the issue I thought I had, neither when downgrading back to Go1.11. The pointer to the context is always copied.

There might be other issues with this shallow clone that using the new .Clone() will fix, but that's not what this issue was about and I will therefor close.
Thank you for pointing this out @willmo.