[clangd] Set diag data before emitting

[kadircet]

Summary

Also fixes a benign use-after-free.

clang-tools-extra/clangd/Diagnostics.cpp

for (auto &Note : D.Notes) {
       RelInfo.location.range = Note.Range;
       RelInfo.location.uri =
           URIForFile::canonicalize(*Note.AbsFile, File.file());
       RelInfo.message = noteMessage(D, Note, Opts);
       Main.relatedInformation->push_back(std::move(RelInfo));
     }
   }
   Main.tags = D.Tags;
+  // FIXME: Get rid of the copies here by taking in a mutable clangd::Diag.
+  for (auto &Entry : D.OpaqueData)
+    Main.data.insert({Entry.first, Entry.second});
   OutFn(std::move(Main), D.Fixes);
 
   // If we didn't emit the notes as relatedLocations, emit separate diagnostics
   // so the user can find the locations easily.
   if (!Opts.EmitRelatedLocations)
     for (auto &Note : D.Notes) {
       if (!Note.InsideMainFile)
         continue;
       clangd::Diagnostic Res;
       Res.severity = getSeverity(Note.Severity);
       Res.range = Note.Range;
       Res.message = noteMessage(D, Note, Opts);
       OutFn(std::move(Res), llvm::ArrayRef<Fix>());
     }
-
-  // FIXME: Get rid of the copies here by taking in a mutable clangd::Diag.
-  for (auto &Entry : D.OpaqueData)
-    Main.data.insert({Entry.first, Entry.second});
 }
 
 int getSeverity(DiagnosticsEngine::Level L) {
   switch (L) {
   case DiagnosticsEngine::Remark:
     return 4;
   case DiagnosticsEngine::Note:
     return 3;

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

 #include "TestTU.h"
 #include "TidyProvider.h"
 #include "index/MemIndex.h"
 #include "support/Context.h"
 #include "support/Path.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/JSON.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/TargetSelect.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <algorithm>
 #include <memory>
 
 namespace clang {
TEST(DiagnosticsTest, ToLSP) {
   D.Name = "undeclared_var_use";
   D.Source = clangd::Diag::Clang;
   D.Message = "something terrible happened";
   D.Range = {pos(1, 2), pos(3, 4)};
   D.InsideMainFile = true;
   D.Severity = DiagnosticsEngine::Error;
   D.File = "foo/bar/main.cpp";
   D.AbsFile = std::string(MainFile.file());
+  D.OpaqueData["test"] = "bar";
 
   clangd::Note NoteInMain;
   NoteInMain.Message = "declared somewhere in the main file";
   NoteInMain.Range = {pos(5, 6), pos(7, 8)};
   NoteInMain.Severity = DiagnosticsEngine::Remark;
   NoteInMain.File = "../foo/bar/main.cpp";
   NoteInMain.InsideMainFile = true;
   NoteInMain.AbsFile = std::string(MainFile.file());
TEST(DiagnosticsTest, ToLSP) {
   MainLSP.message =
       R"(Something terrible happened (fix available)
 
 main.cpp:6:7: remark: declared somewhere in the main file
 
 ../foo/baz/header.h:10:11:
 note: declared somewhere in the header file)";
   MainLSP.tags = {DiagnosticTag::Unnecessary};
+  MainLSP.data = D.OpaqueData;
 
   clangd::Diagnostic NoteInMainLSP;
   NoteInMainLSP.range = NoteInMain.Range;
   NoteInMainLSP.severity = getSeverity(DiagnosticsEngine::Remark);
   NoteInMainLSP.message = R"(Declared somewhere in the main file
 
 main.cpp:2:3: error: something terrible happened)";