[clang] [clang][ssaf] Add `JSONFormat` serialization support for `LUSummary` and `LUSummaryEncoding` (PR #184037)

[Balázs Benics via cfe-commits]

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@@ -110,7 +110,8 @@ std::map<SummaryName, JSONFormat::FormatInfo> JSONFormat::initFormatInfos() {
   std::map<SummaryName, FormatInfo> FormatInfos;
   for (const auto &FormatInfoEntry : llvm::Registry<FormatInfo>::entries()) {
     std::unique_ptr<FormatInfo> Info = FormatInfoEntry.instantiate();
-    bool Inserted = FormatInfos.try_emplace(Info->ForSummary, *Info).second;
+    bool Inserted =
+        FormatInfos.try_emplace(Info->ForSummary, std::move(*Info)).second;
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steakhal wrote:

I was looking at this `std::move` and I was worried about it.

In `try_emplace` the "key" is taken as a const ref. We also convert (potentially consume) the "*Info" - the object that happens to be the target of the const ref representing the key.
Consequently, if the code could move out the guts of "*Info" before the "key" is used, we would end up with an empty string (because a moved-from std::string is well-specified to be empty - that's our luck, otherwise it would be UB with a user-after-move for other types).

I don't think any implementation would put the key into the map after moving in the data - but technically they could how I read the standard. So I'd opt for not having this `std::move` here.

https://github.com/llvm/llvm-project/pull/184037