host: Allow comments in JSON files (#1070)

host: Allow comments in JSON files

src/installer/corehost/cli/json_parser.cpp

@@ -84,9 +84,11 @@ bool json_parser_t::parse_json(const pal::string_t& context)
     // UTF-8 and the host expects wide strings.  m_document will store
     // data in UTF-16 (with pal::char_t as the character type), but it
     // has to know that data is encoded in UTF-8 to convert during parsing.
-    m_document.Parse<rapidjson::ParseFlag::kParseStopWhenDoneFlag, rapidjson::UTF8<>>(m_json.data());
+    constexpr auto flags = rapidjson::ParseFlag::kParseStopWhenDoneFlag
+                         | rapidjson::ParseFlag::kParseCommentsFlag;
+    m_document.Parse<flags, rapidjson::UTF8<>>(m_json.data());
 #else
-    m_document.ParseInsitu(m_json.data());
+    m_document.ParseInsitu<rapidjson::ParseFlag::kParseCommentsFlag>(m_json.data());
 #endif
 
     if (m_document.HasParseError())

src/installer/test/Assets/TestUtils/SDKLookup/dotnet.runtimeconfig.json

 {
   "runtimeOptions": {
+    /* This is a multiline comment to test that the JSON parser is correctly
+     * set up to ignore them. */
     "framework": {
-      "name": "Microsoft.NETCore.App",
-      "version": "9999.0.0"
+      "name": "Microsoft.NETCore.App", // And this is a single-line comment
+      "version": "9999.0.0"            // that should be ignored by the parser
     }
   }
 }
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