[clangd] Improve name conflict detection

[kbobyrev]

Summary

Follow-up on D95925: adds better detection for function arguments and also
checks for conflicts in muli-variable init statements in ForStmt.

[hokein]

Thanks!

clang-tools-extra/clangd/refactor/Rename.cpp

343

I'd use get<FunctionProtoTypeLoc> which seems safer -- typeLoc is a very generic class

[kbobyrev]

Use FunctionProtoTypeLoc

[kbobyrev]

Can't instantiate DynTypedNode with FunctionProtoTypeLoc, has to be just TypeLoc :(

clang-tools-extra/clangd/refactor/Rename.cpp

const NamedDecl *lookupSiblingWithinEnclosingScope(ASTContext &Ctx,
   // not invalidated.
   DynTypedNodeList Storage(DynTypedNode::create(RenamedDecl));
   auto GetSingleParent = [&](const DynTypedNode &Node) -> const DynTypedNode * {
     Storage = Ctx.getParents(Node);
     return (Storage.size() == 1) ? Storage.begin() : nullptr;
   };
 
   // We need to get to the enclosing scope: NamedDecl's parent is typically
-  // DeclStmt, so enclosing scope would be the second order parent.
+  // DeclStmt (or FunctionProtoTypeLoc in case of function arguments), so
+  // enclosing scope would be the second order parent.
   const auto *Parent = GetSingleParent(DynTypedNode::create(RenamedDecl));
-  if (!Parent || !Parent->get<DeclStmt>())
+  if (!Parent || !(Parent->get<DeclStmt>() || Parent->get<TypeLoc>()))
     return nullptr;
   Parent = GetSingleParent(*Parent);
 
   // The following helpers check corresponding AST nodes for variable
   // declarations with the name collision.
   auto CheckDeclStmt = [&](const DeclStmt *DS,
                            StringRef Name) -> const NamedDecl * {
     if (!DS)
const NamedDecl *lookupSiblingWithinEnclosingScope(ASTContext &Ctx,
   // condition, also check the CompoundStmt in the body.
   if (const auto *EnclosingIf = Parent->get<IfStmt>()) {
     if (const auto *Result = CheckCompoundStmt(EnclosingIf->getElse(), NewName))
       return Result;
     return CheckCompoundStmt(EnclosingIf->getThen(), NewName);
   }
   if (const auto *EnclosingWhile = Parent->get<WhileStmt>())
     return CheckCompoundStmt(EnclosingWhile->getBody(), NewName);
-  if (const auto *EnclosingFor = Parent->get<ForStmt>())
+  if (const auto *EnclosingFor = Parent->get<ForStmt>()) {
+    // Check for conflicts with other declarations within initialization
+    // statement.
+    if (const auto *Result = CheckDeclStmt(
+            dyn_cast_or_null<DeclStmt>(EnclosingFor->getInit()), NewName))
+      return Result;
     return CheckCompoundStmt(EnclosingFor->getBody(), NewName);
+  }
+  if (const auto *EnclosingFunction = Parent->get<FunctionDecl>()) {
+    // Check for conflicts with other arguments.
+    for (const auto *Parameter : EnclosingFunction->parameters())
+      if (Parameter != &RenamedDecl && Parameter->getName() == NewName)
+        return Parameter;
+    return CheckCompoundStmt(EnclosingFunction->getBody(), NewName);
+  }
 
   return nullptr;
 }
 
 // Lookup the declarations (if any) with the given Name in the context of
 // RenameDecl.
 const NamedDecl *lookupSiblingsWithinContext(ASTContext &Ctx,
                                              const NamedDecl &RenamedDecl,

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

Case Cases[] = {
                ++Something) {
             int V^ar;
           }
         }
       )cpp",
        "conflict", !HeaderFile, nullptr, "Conflict"},
 
       {R"cpp(
+        void func() {
+          for (int V^ar = 14, Conflict = 42;;) {
+          }
+        }
+      )cpp",
+       "conflict", !HeaderFile, nullptr, "Conflict"},
+
+      {R"cpp(
         void func(int Conflict) {
           bool V^ar;
         }
       )cpp",
        "conflict", !HeaderFile, nullptr, "Conflict"},
 
+      {R"cpp(
+        void func(int V^ar) {
+          bool Conflict;
+        }
+      )cpp",
+       "conflict", !HeaderFile, nullptr, "Conflict"},
+
+      {R"cpp(
+        void func(int V^ar, int Conflict) {
+        }
+      )cpp",
+       "conflict", !HeaderFile, nullptr, "Conflict"},
+
       {R"cpp(// Trying to rename into the same name, SameName == SameName.
         void func() {
           int S^ameName;
         }
       )cpp",
        "new name is the same", !HeaderFile, nullptr, "SameName"},
       {R"cpp(// Ensure it doesn't associate base specifier with base name.
         struct A {};