Improvement: span_id should not break strict aliasing. (#1068)

hcoona · web-flow · commit 69fdf6715461 · 2021-11-15T22:44:54.000-08:00
diff --git a/api/include/opentelemetry/trace/span_id.h b/api/include/opentelemetry/trace/span_id.h
@@ -60,8 +60,8 @@ class SpanId final
   // Returns false if the SpanId is all zeros.
   bool IsValid() const noexcept
   {
-    static_assert(kSize == 8, "update is needed if kSize is not 8");
-    return *reinterpret_cast<const uint64_t *>(&rep_) != 0ull;
+    static constexpr uint8_t kEmptyRep[kSize] = {0};
+    return memcmp(rep_, kEmptyRep, kSize) != 0;
   }
 
   // Copies the opaque SpanId data to dest.

Original file line number	Diff line number	Diff line change
`@@ -60,8 +60,8 @@ class SpanId final`
`60`	`60`	`// Returns false if the SpanId is all zeros.`
`61`	`61`	`bool IsValid() const noexcept`
`62`	`62`	`{`
`63`		`- static_assert(kSize == 8, "update is needed if kSize is not 8");`
`64`		`- return reinterpret_cast<const uint64_t >(&rep_) != 0ull;`
	`63`	`+ static constexpr uint8_t kEmptyRep[kSize] = {0};`
	`64`	`+ return memcmp(rep_, kEmptyRep, kSize) != 0;`
`65`	`65`	`}`
`66`	`66`
`67`	`67`	`// Copies the opaque SpanId data to dest.`