[clangd] Print type for VarTemplateDecl in hover.

[lh123]

Summary

Print type for VarTemplateDecl in hover.

[sammccall]

Thanks!

clang-tools-extra/clangd/Hover.cpp

HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
   if (const FunctionDecl *FD = getUnderlyingFunction(D))
     fillFunctionTypeAndParams(HI, D, FD, PP);
   else if (const auto *VD = dyn_cast<ValueDecl>(D))
     HI.Type = printType(VD->getType(), PP);
   else if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(D))
     HI.Type = TTP->wasDeclaredWithTypename() ? "typename" : "class";
   else if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(D))
     HI.Type = printType(TTP, PP);
+  else if (const auto *VT = dyn_cast<VarTemplateDecl>(D))
+    HI.Type = printType(VT->getTemplatedDecl()->getType(), PP);
 
   // Fill in value with evaluated initializer if possible.
   if (const auto *Var = dyn_cast<VarDecl>(D)) {
     if (const Expr *Init = Var->getInit())
       HI.Value = printExprValue(Init, Ctx);
   } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
     // Dependent enums (e.g. nested in template classes) don't have values yet.
     if (!ECD->getType()->isDependentType())

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

class Foo {})cpp";
             ^[[{]]1} // FIXME: why the hover range is 1 character?
           };
          )cpp",
        [](HoverInfo &HI) {
          HI.Name = "expression";
          HI.Kind = index::SymbolKind::Unknown;
          HI.Type = "int[10]";
          HI.Value = "{1}";
+       }},
+      {// Var template decl
+       R"cpp(
+          using m_int = int;
+
+          template <int Size> m_int ^[[arr]][Size];
+         )cpp",
+       [](HoverInfo &HI) {
+         HI.Name = "arr";
+         HI.Kind = index::SymbolKind::Variable;
+         HI.Type = "m_int[Size]";
+         HI.NamespaceScope = "";
+         HI.Definition = "template <int Size> m_int arr[Size]";
+         HI.TemplateParameters = {{{"int"}, {"Size"}, llvm::None}};
+       }},
+      {// Var template decl specialization
+       R"cpp(
+          using m_int = int;
+
+          template <int Size> m_int arr[Size];
+
+          template <> m_int ^[[arr]]<4>[4];
+         )cpp",
+       [](HoverInfo &HI) {
+         HI.Name = "arr<4>";
+         HI.Kind = index::SymbolKind::Variable;
+         HI.Type = "m_int[4]";
+         HI.NamespaceScope = "";
+         HI.Definition = "m_int arr[4]";
        }}};
   for (const auto &Case : Cases) {
     SCOPED_TRACE(Case.Code);
 
     Annotations T(Case.Code);
     TestTU TU = TestTU::withCode(T.code());
     TU.ExtraArgs.push_back("-std=c++17");
     // Types might be different depending on the target triplet, we chose a