Identify logger with schemaURL in global logger provider (#5375)

Fix #5366

log/internal/global/log.go

@@ -15,7 +15,7 @@ import (
 // instLib defines the instrumentation library a logger is created for.
 //
 // Do not use sdk/instrumentation (API cannot depend on the SDK).
-type instLib struct{ name, version string }
+type instLib struct{ name, version, schemaURL string }
 
 type loggerProvider struct {
 	embedded.LoggerProvider
@@ -37,7 +37,11 @@ func (p *loggerProvider) Logger(name string, options ...log.LoggerOption) log.Lo
 	}
 
 	cfg := log.NewLoggerConfig(options...)
-	key := instLib{name, cfg.InstrumentationVersion()}
+	key := instLib{
+		name:      name,
+		version:   cfg.InstrumentationVersion(),
+		schemaURL: cfg.SchemaURL(),
+	}
 
 	if p.loggers == nil {
 		l := &logger{name: name, options: options}

log/internal/global/log_test.go

@@ -158,3 +158,39 @@ func TestDelegation(t *testing.T) {
 		assert.Equal(t, 1, post.(*testLogger).enabledN, "Enabled not delegated")
 	}
 }
+
+func TestLoggerIdentity(t *testing.T) {
+	type id struct{ name, ver, url string }
+
+	ids := []id{
+		{"name-a", "version-a", "url-a"},
+		{"name-a", "version-a", "url-b"},
+		{"name-a", "version-b", "url-a"},
+		{"name-a", "version-b", "url-b"},
+		{"name-b", "version-a", "url-a"},
+		{"name-b", "version-a", "url-b"},
+		{"name-b", "version-b", "url-a"},
+		{"name-b", "version-b", "url-b"},
+	}
+
+	provider := &loggerProvider{}
+	newLogger := func(i id) log.Logger {
+		return provider.Logger(
+			i.name,
+			log.WithInstrumentationVersion(i.ver),
+			log.WithSchemaURL(i.url),
+		)
+	}
+
+	for i, id0 := range ids {
+		for j, id1 := range ids {
+			l0, l1 := newLogger(id0), newLogger(id1)
+
+			if i == j {
+				assert.Samef(t, l0, l1, "logger(%v) != logger(%v)", id0, id1)
+			} else {
+				assert.NotSamef(t, l0, l1, "logger(%v) == logger(%v)", id0, id1)
+			}
+		}
+	}
+}