Simplify result/expected.h

- The `CF_EXPECT*` macros never used the `Result&&` versions of
  `TypeIsSuccess` and `OutcomeDereference`.
- One use of `type_traits` conditional logic in `OutcomeDereference` was
  replaced with overload resolution.

Author: Databean

base/cvd/cuttlefish/result/expect.h

@@ -56,14 +56,11 @@ T OutcomeDereference(std::optional<T>&& value) {
   return std::move(*value);
 }
 
+inline void OutcomeDereference(Result<void>&&) {}
+
 template <typename T>
-typename std::conditional_t<std::is_void_v<T>, bool, T> OutcomeDereference(
-    Result<T>&& result) {
-  if constexpr (std::is_void<T>::value) {
-    return result.ok();
-  } else {
-    return std::move(*result);
-  }
+T OutcomeDereference(Result<T>&& result) {
+  return std::move(*result);
 }
 
 template <typename T>
@@ -84,11 +81,6 @@ bool TypeIsSuccess(Result<T>& value) {
   return value.ok();
 }
 
-template <typename T>
-bool TypeIsSuccess(Result<T>&& value) {
-  return value.ok();
-}
-
 inline auto ErrorFromType(bool) { return StackTraceError(); }
 
 template <typename T>
@@ -101,11 +93,6 @@ auto ErrorFromType(Result<T>& value) {
   return value.error();
 }
 
-template <typename T>
-auto ErrorFromType(Result<T>&& value) {
-  return value.error();
-}
-
 #define CF_EXPECT_OVERLOAD(_1, _2, NAME, ...) NAME
 
 #define CF_EXPECT2(RESULT, MSG)                               \

base/cvd/cuttlefish/result/result.h

@@ -15,5 +15,5 @@
 
 #pragma once
 
-#include "cuttlefish/result/expect.h"  // IWYU pragma: export
+#include "cuttlefish/result/expect.h"       // IWYU pragma: export
 #include "cuttlefish/result/result_type.h"  // IWYU pragma: export