[clangd] Keep count of delayed diagnostics

[kadircet]

Summary

This is useful when amending diagnostics messages to indicate possible
fixes.

Depends on D98505

[sammccall]

This seems like something we can delay until we're sure it'll do what we want? (e.g. we see that we either usually know synchronously whether lazy fixes will be present, or can predict it with high confidence)

[kadircet]

In D98621#2626898, @sammccall wrote:

This seems like something we can delay until we're sure it'll do what we want? (e.g. we see that we either usually know synchronously whether lazy fixes will be present, or can predict it with high confidence)

Yeah SG.

clang-tools-extra/clangd/Diagnostics.h

 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/SourceMgr.h"
 #include <cassert>
+#include <cstddef>
 #include <memory>
 #include <string>
 #include <vector>
 
 namespace clang {
 namespace tidy {
 class ClangTidyContext;
 } // namespace tidy
enum DiagSource {
     Clang,
     ClangTidy,
     ClangdConfig,
   } Source = Unknown;
   /// Elaborate on the problem, usually pointing to a related piece of code.
   std::vector<Note> Notes;
   /// *Alternative* fixes for this diagnostic, one should be chosen.
   std::vector<Fix> Fixes;
+  /// Number of fixes available that are different than fixes above.
+  std::size_t DelayedFixCount = 0;
 };
 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Diag &D);
 
 Diag toDiag(const llvm::SMDiagnostic &, Diag::DiagSource Source);
 
 /// Conversion to LSP diagnostics. Formats the error message of each diagnostic
 /// to include all its notes. Notes inside main file are also provided as
 /// separate diagnostics with their corresponding fixits. Notes outside main

clang-tools-extra/clangd/Diagnostics.cpp

 ///     main.cpp:3:5: note: candidate function not viable: requires 2 arguments
 ///
 ///     dir1/dir2/dir3/../../dir4/header.h:12:23
 ///     note: candidate function not viable: requires 3 arguments
 std::string mainMessage(const Diag &D, const ClangdDiagnosticOptions &Opts) {
   std::string Result;
   llvm::raw_string_ostream OS(Result);
   OS << D.Message;
-  if (Opts.DisplayFixesCount && !D.Fixes.empty())
-    OS << " (" << (D.Fixes.size() > 1 ? "fixes" : "fix") << " available)";
+  auto TotalFixCount = D.Fixes.size() + D.DelayedFixCount;
+  if (Opts.DisplayFixesCount && TotalFixCount > 0)
+    OS << " (" << (TotalFixCount > 1 ? "fixes" : "fix") << " available)";
   // If notes aren't emitted as structured info, add them to the message.
   if (!Opts.EmitRelatedLocations)
     for (auto &Note : D.Notes) {
       OS << "\n\n";
       printDiag(OS, Note);
     }
   OS.flush();
   return capitalize(std::move(Result));

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

 }
 
 TEST_F(LSPTest, DiagModuleTest) {
   static constexpr llvm::StringLiteral DiagMsg = "DiagMsg";
   class DiagModule final : public FeatureModule {
     struct DiagHooks : public ParseASTHooks {
       void sawDiagnostic(const clang::Diagnostic &, clangd::Diag &D) override {
         D.Message = DiagMsg.str();
+        ++D.DelayedFixCount;
       }
     };
 
   public:
     std::unique_ptr<ParseASTHooks> astHooks() override {
       return std::make_unique<DiagHooks>();
     }
   };
   FeatureModules.add(std::make_unique<DiagModule>());
 
   auto &Client = start();
   Client.didOpen("foo.cpp", "test;");
   EXPECT_THAT(Client.diagnostics("foo.cpp"),
-              llvm::ValueIs(testing::ElementsAre(DiagMessage(DiagMsg))));
+              llvm::ValueIs(testing::ElementsAre(
+                  DiagMessage(DiagMsg.str() + " (fix available)"))));
 }
 } // namespace
 } // namespace clangd
 } // namespace clang