net/http: use of request body in WASM Roundtripper panics

[johanbrandhorst]

What version of Go are you using (go version)?

tip

Does this issue reproduce with the latest release?

No, no WASM

What operating system and processor architecture are you using (go env)?

linux amd64

What did you do?

I sent a request with a body in a binary compiled for WASM.

What did you expect to see?

The request would be sent successfully.

What did you see instead?

When using a request body with the new http.RoundTripper implemented for WASM, the call to set the body on the JavaScript fetch object panics.

Notes

Initially reported by John Marshall in https://groups.google.com/forum/#!topic/golang-nuts/7ZIU-YKoDVw. The bug was introduced with bafe466, a simple case of missing a use of a slice in roundtrip_js.go: https://github.com/golang/go/blob/master/src/net/http/roundtrip_js.go#L63.

[johanbrandhorst]

I will submit a fix for this.

[gopherbot]

Change https://golang.org/cl/123537 mentions this issue: net/http: correct use of byte slice in js syscall