[Clangd] Failed to decode params using 1.x-compatible request message

[malaperle-ericsson]

Summary

textDocument/completion sends a TextDocumentPositionParams message in the 2.x
and 3.x. But in 1.x it was instead a TextDocumentPosition with inlined
parameters. This means that the "uri" field is at the top level and not in
textDocument. Because of this, some clients that maintain compability with 1.x
have both uri and textDocument.uri. Clangd, however, early returns in the
presence of anything but 'textDocument' or 'position' which prevents a client
compatible with both 3.x and 1.x to work correctly. If Clangd was a bit more
permissive (no early return), clients implementing all the versions of the
protocol would work.

[bkramer]

A test case would be nice.

[malaperle-ericsson]

Add test

[bkramer]

lg

[malaperle-ericsson]

Could you commit it? I don't have commit access :) Thanks!

clang-tools-extra/trunk/clangd/Protocol.cpp

for (auto &NextKeyValue : *Params) {
     if (!KeyString)
       return llvm::None;
 
     llvm::SmallString<10> KeyStorage;
     StringRef KeyValue = KeyString->getValue(KeyStorage);
     auto *Value =
         dyn_cast_or_null<llvm::yaml::MappingNode>(NextKeyValue.getValue());
     if (!Value)
-      return llvm::None;
+      continue;
 
     llvm::SmallString<10> Storage;
     if (KeyValue == "textDocument") {
       auto Parsed = TextDocumentIdentifier::parse(Value);
       if (!Parsed)
         return llvm::None;
       Result.textDocument = std::move(*Parsed);
     } else if (KeyValue == "position") {

clang-tools-extra/trunk/test/clangd/completion.test

 {"jsonrpc":"2.0","id":1,"method":"textDocument/completion","params":{"textDocument":{"uri":"file:/main.cpp"},"position":{"line":3,"character":5}}}
 # Test authority-less URI
 #
 # CHECK: {"jsonrpc":"2.0","id":1,"result":[
 # CHECK-DAG: {"label":"a","kind":5}
 # CHECK-DAG: {"label":"bb","kind":5}
 # CHECK-DAG: {"label":"ccc","kind":5}
 # CHECK: ]}
+
+Content-Length: 172
+
+{"jsonrpc":"2.0","id":1,"method":"textDocument/completion","params":{"textDocument":{"uri":"file:///main.cpp"},"uri":"file:///main.cpp","position":{"line":3,"character":5}}}
+# Test params parsing in the presence of a 1.x-compatible client (inlined "uri")
+#
+# CHECK: {"jsonrpc":"2.0","id":1,"result":[
+# CHECK-DAG: {"label":"a","kind":5}
+# CHECK-DAG: {"label":"bb","kind":5}
+# CHECK-DAG: {"label":"ccc","kind":5}
+# CHECK: ]}
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}