Ensure exported struct in sdk/log are not comparable (#5693)

Ensure the `Record` and `Provider` continue to be non-comparable.

Restrict `BatchProcessor` and `SimpleProcessor` to be non-comparable.

There is no obvious reason an end-user will need to compare these types,
and we want to keep the possibility of changing the internals without
changing this behavior.

if comparability is required by end-users in the future we can add
`Equal(other T)` methods in the future.

CHANGELOG.md

@@ -24,6 +24,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - `SimpleProcessor.Enabled` in `go.opentelemetry.io/otel/sdk/log` now returns `false` if the exporter is `nil`. (#5665)
 - Update the concurrency requirements of `Exporter` in `go.opentelemetry.io/otel/sdk/log`. (#5666)
 - `SimpleProcessor` in `go.opentelemetry.io/otel/sdk/log` synchronizes `OnEmit` calls. (#5666)
+- The `SimpleProcessor` type in `go.opentelemetry.io/otel/sdk/log` is no longer comparable. (#5693)
+- The `BatchProcessor` type in `go.opentelemetry.io/otel/sdk/log` is no longer comparable. (#5693)
 
 ### Fixed
 

sdk/log/batch.go

@@ -96,6 +96,8 @@ type BatchProcessor struct {
 
 	// stopped holds the stopped state of the BatchProcessor.
 	stopped atomic.Bool
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
 }
 
 // NewBatchProcessor decorates the provided exporter

sdk/log/provider.go

@@ -69,6 +69,8 @@ type LoggerProvider struct {
 	loggers   map[instrumentation.Scope]*logger
 
 	stopped atomic.Bool
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
 }
 
 // Compile-time check LoggerProvider implements log.LoggerProvider.

sdk/log/record.go

@@ -86,6 +86,8 @@ type Record struct {
 
 	attributeValueLengthLimit int
 	attributeCountLimit       int
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
 }
 
 func (r *Record) addDropped(n int) {

sdk/log/simple.go

@@ -17,6 +17,8 @@ var _ Processor = (*SimpleProcessor)(nil)
 type SimpleProcessor struct {
 	mu       sync.Mutex
 	exporter Exporter
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
 }
 
 // NewSimpleProcessor is a simple Processor adapter.