based on (but to be merged to main individually)

• feat(metrics): Trace-connected Metrics #4834
• ref!: remove Experimental from Metrics API #5023

Summary

My little weekend-project:
Add a Diagnostic-Analyzer to our Compiler-Extensions, that warn users when a metric would not be emitted due to an unsupported numeric value type -or- likewise, a SentryMetric.TryGetValue<> invocation with an unsupported numeric value type is detected.

Changelog Entry

Report a new Diagnostic (SENTRY1001) when a Metrics-API is invoked with an unsupported numeric type

Remarks

For the numeric type of a Metric, we currently allow 64-bit sized integral (signed) and floating-point numbers.
That means that e.g. ulong, System.Int128, or decimal are currently not supported by Sentry.
The compile-time constraint of Sentry.SentryMetric<T> only constrains to non-nullable value types.
Alternatively, we could have implemented respectively types overloads for the method groups:

public void EmitCounter(string name, long value);
public void EmitCounter(string name, float value);
public void EmitCounter(string name, double value);
public void EmitCounter(string name, long value, Scope? scope)
public void EmitCounter(string name, float value, Scope? scope)
public void EmitCounter(string name, double value, Scope? scope)
public void EmitCounter ..

public void EmitGauge ..
public void EmitDistribution ..

To avoid this explosion of overloads per method group,
and be similar to the implementation of System.Diagnostics.Metrics,
we are not compile-time constraining unsupported types,
but are instead run-time constraining unsupported types (no-op and Debug-Diagnostic-Logging).

To still warn users unfamiliar with the System.Diagnostics.Metrics.Meter-based APIs,
I built an Analyzer over some weekends to guide new users.

Examples

options.Experimental.SetBeforeSendMetric(static SentryMetric? (SentryMetric metric) =>
{
    if (metric.TryGetValue<int>(out int int32) && int32 < 0)
    {
        return null;
    }

    if (metric.TryGetValue<uint>(out uint uint32) && uint32 == 0) //SENTRY1001
    {
        return null;
    }

    return metric;
});

SentrySdk.Experimental.Metrics.EmitCounter("my.counter", 1);
SentrySdk.Experimental.Metrics.EmitCounter("my.counter", 1m); //SENTRY1001
SentrySdk.Experimental.Metrics.EmitCounter("my.counter", StringComparison.CurrentCultureIgnoreCase); //SENTRY1001
SentrySdk.Experimental.Metrics.EmitCounter<ulong>("my.counter", default); //SENTRY1001