[llvm] GSym aggregated output to JSON file (PR #81763)

[Greg Clayton via llvm-commits]

================
@@ -515,10 +520,31 @@ int llvm_gsymutil_main(int argc, char **argv, const llvm::ToolContext &) {
     // Call error() if we have an error and it will exit with a status of 1
     if (auto Err = convertFileToGSYM(Aggregation))
       error("DWARF conversion failed: ", std::move(Err));
+
     // Report the errors from aggregator:
     Aggregation.EnumerateResults([&](StringRef category, unsigned count) {
       OS << category << " occurred " << count << " time(s)\n";
     });
+    if (!AggregateJsonFile.empty()) {
+      std::error_code EC;
+      raw_fd_ostream JsonStream(AggregateJsonFile, EC, sys::fs::OF_Text);
+      if (EC) {
+        OS << "error opening aggregate error json file '" << AggregateJsonFile
+           << "' for writing: " << EC.message() << '\n';
+        return 1;
+      }
+      JsonStream << "{\"errors\":[\n";
+      bool prev = false;
+      Aggregation.EnumerateResults([&](StringRef category, unsigned count) {
+        if (prev)
+          JsonStream << ",\n";
+        JsonStream << "{\"category\":\"";
+        llvm::printEscapedString(category, JsonStream);
+        JsonStream << "\",\"count\":" << count << "}";
+        prev = true;
+      });
+      JsonStream << "\n]}\n";
----------------
clayborg wrote:

To create this kind of thing with objects the JSON code would look like:
```
llvm::json::Object category_dict;
Aggregation.EnumerateResults([&](StringRef category, unsigned count) {
  llvm::json::Object category_info;
  category_info.try_emplace("count", count);
  category_dict.try_emplace(category, category_info);
});
llvm::json::Object json_output;
json_output.try_emplace("error-categories", category_dict);
// Convert JSON objects to a string
std::string s;
llvm::raw_string_ostream strm(s);
strm << json_output;
```


https://github.com/llvm/llvm-project/pull/81763