[clang-tools-extra] [clangd] extend and rearrange doxygen hover documentation (PR #152918)

[Yanzuo Liu via cfe-commits]

================
@@ -135,7 +135,11 @@ std::string getDeclComment(const ASTContext &Ctx, const NamedDecl &Decl) {
     std::string RawDoc;
     llvm::raw_string_ostream OS(RawDoc);
 
-    V.parameterDocToString(dyn_cast<ParmVarDecl>(&Decl)->getName(), OS);
+    if (isa<ParmVarDecl>(Decl))
+      V.parameterDocToString(dyn_cast<ParmVarDecl>(&Decl)->getName(), OS);
+    else
+      V.templateTypeParmDocToString(
+          dyn_cast<TemplateTypeParmDecl>(&Decl)->getName(), OS);
----------------
zwuis wrote:

Use `cast` instead of `dyn_cast` if we already know its type.

You can also write
```cpp
if (auto *TTPD = dyn_cast<...>(Decl))
  // use TTPD
else
  // use cast<...>(Decl)
```

https://github.com/llvm/llvm-project/pull/152918