[clangd] Drop returntype/type when hovering over type-ish names

Summary:
Some names, e.g. constructor/destructor/conversions, already contain
the type info, no need to duplicate them in the hoverinfo.

Fixes clangd/clangd#252

Reviewers: sammccall, ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73110

Author: kadircet

clang-tools-extra/clangd/Hover.cpp

@@ -266,20 +266,19 @@ void fillFunctionTypeAndParams(HoverInfo &HI, const Decl *D,
     }
   }
 
-  if (const auto *CCD = llvm::dyn_cast<CXXConstructorDecl>(FD)) {
-    // Constructor's "return type" is the class type.
-    HI.ReturnType = declaredType(CCD->getParent()).getAsString(Policy);
-    // Don't provide any type for the constructor itself.
-  } else if (llvm::isa<CXXDestructorDecl>(FD)) {
-    HI.ReturnType = "void";
-  } else {
-    HI.ReturnType = printType(FD->getReturnType(), Policy);
+  // We don't want any type info, if name already contains it. This is true for
+  // constructors/destructors and conversion operators.
+  const auto NK = FD->getDeclName().getNameKind();
+  if (NK == DeclarationName::CXXConstructorName ||
+      NK == DeclarationName::CXXDestructorName ||
+      NK == DeclarationName::CXXConversionFunctionName)
+    return;
 
-    QualType QT = FD->getType();
-    if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) // Lambdas
-      QT = VD->getType().getDesugaredType(D->getASTContext());
-    HI.Type = printType(QT, Policy);
-  }
+  HI.ReturnType = printType(FD->getReturnType(), Policy);
+  QualType QT = FD->getType();
+  if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) // Lambdas
+    QT = VD->getType().getDesugaredType(D->getASTContext());
+  HI.Type = printType(QT, Policy);
   // FIXME: handle variadics.
 }
 

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

@@ -327,7 +327,6 @@ class Foo {})cpp";
          HI.Name = "X";
          HI.LocalScope = "X<T *>::"; // FIXME: X<T *, void>::
          HI.Kind = index::SymbolKind::Constructor;
-         HI.ReturnType = "X<T *>";
          HI.Definition = "X()";
          HI.Parameters.emplace();
        }},
@@ -337,10 +336,18 @@ class Foo {})cpp";
          HI.Name = "~X";
          HI.LocalScope = "X::";
          HI.Kind = index::SymbolKind::Destructor;
-         HI.ReturnType = "void";
          HI.Definition = "~X()";
          HI.Parameters.emplace();
        }},
+      {"class X { operator [[in^t]](); };",
+       [](HoverInfo &HI) {
+         HI.NamespaceScope = "";
+         HI.Name = "operator int";
+         HI.LocalScope = "X::";
+         HI.Kind = index::SymbolKind::ConversionFunction;
+         HI.Definition = "operator int()";
+         HI.Parameters.emplace();
+       }},
 
       // auto on lambda
       {R"cpp(