Extend CustomUintFormatter to support enums

ryanofsky · sipa · commit 6f9a1e5ad0a2 · 2020-03-30T15:36:16.000-07:00
Extracted by Pieter Wuille from a comment by Russ Yanofsky, see #18317 (comment).
diff --git a/src/serialize.h b/src/serialize.h
@@ -538,14 +538,15 @@ struct CustomUintFormatter
 
     template <typename Stream, typename I> void Unser(Stream& s, I& v)
     {
-        static_assert(std::numeric_limits<I>::max() >= MAX && std::numeric_limits<I>::min() <= 0, "CustomUintFormatter type too small");
+        using U = typename std::conditional<std::is_enum<I>::value, std::underlying_type<I>, std::common_type<I>>::type::type;
+        static_assert(std::numeric_limits<U>::max() >= MAX && std::numeric_limits<U>::min() <= 0, "Assigned type too small");
         uint64_t raw = 0;
         if (BigEndian) {
             s.read(((char*)&raw) + 8 - Bytes, Bytes);
-            v = be64toh(raw);
+            v = static_cast<I>(be64toh(raw));
         } else {
             s.read((char*)&raw, Bytes);
-            v = le64toh(raw);
+            v = static_cast<I>(le64toh(raw));
         }
     }
 };

Original file line number	Diff line number	Diff line change
`@@ -538,14 +538,15 @@ struct CustomUintFormatter`
`538`	`538`
`539`	`539`	`template <typename Stream, typename I> void Unser(Stream& s, I& v)`
`540`	`540`	`{`
`541`		`- static_assert(std::numeric_limits<I>::max() >= MAX && std::numeric_limits<I>::min() <= 0, "CustomUintFormatter type too small");`
	`541`	`+ using U = typename std::conditional<std::is_enum<I>::value, std::underlying_type<I>, std::common_type<I>>::type::type;`
	`542`	`+ static_assert(std::numeric_limits<U>::max() >= MAX && std::numeric_limits<U>::min() <= 0, "Assigned type too small");`
`542`	`543`	`uint64_t raw = 0;`
`543`	`544`	`if (BigEndian) {`
`544`	`545`	`s.read(((char*)&raw) + 8 - Bytes, Bytes);`
`545`		`- v = be64toh(raw);`
	`546`	`+ v = static_cast<I>(be64toh(raw));`
`546`	`547`	`} else {`
`547`	`548`	`s.read((char*)&raw, Bytes);`
`548`		`- v = le64toh(raw);`
	`549`	`+ v = static_cast<I>(le64toh(raw));`
`549`	`550`	`}`
`550`	`551`	`}`
`551`	`552`	`};`