[clangd] Add parameter and return type information to completion results

[krasimir]

Summary

This patch adds information about the parameters and return types of completion
candidates.
Previously, for the following code:

struct S {
  int func(int a, double b) const;
};

the completer would only return the label of the candidate func.
Now it will also return the return type int and will format the label for the
candidate as func(int a, double b) const.

[krasimir]

• Add a test case

[krasimir]

• Fix indentation

[krasimir]

• Remove unused method

[krasimir]

• Remove newline

[ilya-biryukov]

clangd/ClangdUnit.cpp

154

Should we also update sortText and filterText, which use label by default, just like insertText?

test/clangd/completion.test

32

Should we repeat repeat the checks added above here too?

41

Again.
Should we repeat repeat the checks added above here too?

[krasimir]

• Remove optional chunks. They might contain control characters

[krasimir]

• Add sortText and filterText

[krasimir]

clangd/ClangdUnit.cpp

154

Good point!

test/clangd/completion.test

32

This test case is about understanding 'file:/main.cpp', so I don't think repeating everything would be beneficial.

[ilya-biryukov]

test/clangd/completion.test

32

Makes sense.
Testing that the output is the same on repeated runs of completion wouldn't probably hurt either.
But if you feel it makes tests too clunky, let's not have it here.

clangd/ClangdUnit.cpp

CompletionItemKind getKind(CXCursorKind K) {
   case CXCursor_MemberRef:
   case CXCursor_TypeRef:
     return CompletionItemKind::Reference;
   default:
     return CompletionItemKind::Missing;
   }
 }
 
+
 class CompletionItemsCollector : public CodeCompleteConsumer {
   std::vector<CompletionItem> *Items;
   std::shared_ptr<clang::GlobalCodeCompletionAllocator> Allocator;
   CodeCompletionTUInfo CCTUInfo;
 
 public:
   CompletionItemsCollector(std::vector<CompletionItem> *Items,
                            const CodeCompleteOptions &CodeCompleteOpts)
       : CodeCompleteConsumer(CodeCompleteOpts, /*OutputIsBinary=*/false),
         Items(Items),
         Allocator(std::make_shared<clang::GlobalCodeCompletionAllocator>()),
         CCTUInfo(Allocator) {}
 
   void ProcessCodeCompleteResults(Sema &S, CodeCompletionContext Context,
                                   CodeCompletionResult *Results,
                                   unsigned NumResults) override {
     for (unsigned I = 0; I != NumResults; ++I) {
       CodeCompletionResult &Result = Results[I];
       CodeCompletionString *CCS = Result.CreateCodeCompletionString(
           S, Context, *Allocator, CCTUInfo,
           CodeCompleteOpts.IncludeBriefComments);
       if (CCS) {
         CompletionItem Item;
+        for (CodeCompletionString::Chunk C : *CCS) {
+          switch (C.Kind) {
+          case CodeCompletionString::CK_ResultType:
+            Item.detail = C.Text;
+            break;
+          default:
+            Item.label += C.Text;
+            break;
+          }
+        }
         assert(CCS->getTypedText());
-        Item.label = CCS->getTypedText();
         Item.kind = getKind(Result.CursorKind);
+        Item.insertText = CCS->getTypedText();
         if (CCS->getBriefComment())
           Item.documentation = CCS->getBriefComment();
         Items->push_back(std::move(Item));
       }
     }
   }
 
   GlobalCodeCompletionAllocator &getAllocator() override { return *Allocator; }
 
   CodeCompletionTUInfo &getCodeCompletionTUInfo() override { return CCTUInfo; }
+
+private:
+  bool isInformative(CodeCompletionString::ChunkKind) const;
 };
 } // namespace
 
 std::vector<CompletionItem>
 ClangdUnit::codeComplete(StringRef Contents, Position Pos,
                          IntrusiveRefCntPtr<vfs::FileSystem> VFS) {
   CodeCompleteOptions CCO;
   CCO.IncludeBriefComments = 1;

test/clangd/completion.test

 # RUN: clangd -run-synchronously < %s | FileCheck %s
 # It is absolutely vital that this file has CRLF line endings.
 #
 Content-Length: 125
 
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 
-Content-Length: 211
+Content-Length: 246
 
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"file:///main.cpp","languageId":"cpp","version":1,"text":"struct fake { int a, bb, ccc; };\nint main() {\n  fake f;\n  f.\n}\n"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"file:///main.cpp","languageId":"cpp","version":1,"text":"struct fake { int a, bb, ccc; int f(int i, const float f) const; };\nint main() {\n  fake f;\n  f.\n}\n"}}}
 
 Content-Length: 148
 
 {"jsonrpc":"2.0","id":1,"method":"textDocument/completion","params":{"textDocument":{"uri":"file:///main.cpp"},"position":{"line":3,"character":5}}}
 # The order of results returned by ASTUnit CodeComplete seems to be
 # nondeterministic, so we check regardless of order.
 #
 # 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-DAG: {"label":"a","kind":5,"detail":"int","insertText":"a"}
+# CHECK-DAG: {"label":"bb","kind":5,"detail":"int","insertText":"bb"}
+# CHECK-DAG: {"label":"ccc","kind":5,"detail":"int","insertText":"ccc"}
+# CHECK-DAG: {"label":"operator=(const fake &)","kind":2,"detail":"fake &","insertText":"operator="}
+# CHECK-DAG: {"label":"~fake()","kind":4,"detail":"void","insertText":"~fake"}
+# CHECK-DAG: {"label":"f(int i, const float f) const","kind":2,"detail":"int","insertText":"f"}
 # CHECK: ]}
 Content-Length: 146
 
 {"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-DAG: {"label":"a","kind":5,"detail":"int","insertText":"a"}
 # 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-DAG: {"label":"a","kind":5,"detail":"int","insertText":"a"}
 # CHECK: ]}
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+