Remove trace.WithRecord() trace start option

[jmacd]

The spec:
https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/trace/api.md#isrecording

Some history:
#223
#188
#192

The task is to implement Span.IsRecording() bool which returns true if the span is not a no-op.

[evantorrie]

@jmacd Can you clarify this a little? I thought #188 did change/add the IsRecording() bool function to the Span interface and all implementations.

[jmacd]

I realize that IsRecording() is implemented. I thought it had been removed.

[jmacd]

Ah, the spec does not support a WithRecord() function that we currently have. It's the sampler's responsibility for deciding if a span records.

[evantorrie]

Was there ever a resolution to open-telemetry/opentelemetry-specification#307

I see @paivagustavo tried in #223 to do this, and ran into the same problem that span.SetName() requires a resampling decision. In the Go implementation, if the span did not already have IsRecording() == true, then there's no data for it to make that decision.

It doesn't look like there has been any change made to the specification and thus calling SetName() still seems to require another call to the sampler.

Found some more issues related to this for background reading:
open-telemetry/opentelemetry-specification#468
#224

and more recently

open-telemetry/opentelemetry-specification#620
open-telemetry/opentelemetry-specification#634

[MrAlias]

I think this has become a duplicate of #192, going to close this and consolidate the conversation there.