[PATCH] D69237: Refactor getDeclAtPosition() to use SelectionTree + targetDecl()

[Nathan Ridge via Phabricator via cfe-commits]

nridge marked 3 inline comments as done.
nridge added inline comments.


================
Comment at: clang-tools-extra/clangd/XRefs.cpp:139
+// that constructor. FIXME(nridge): this should probably be handled in
+// targetDecl() itself.
+const CXXConstructorDecl *findCalledConstructor(const SelectionTree::Node *N) {
----------------
I would appreciate some tips on how we could handle this in `targetDecl()`. Please see more specific comments below.


================
Comment at: clang-tools-extra/clangd/XRefs.cpp:141
+const CXXConstructorDecl *findCalledConstructor(const SelectionTree::Node *N) {
+  if (const VarDecl *VD = N->ASTNode.get<VarDecl>()) {
+    if (const Expr *Init = VD->getInit()) {
----------------
This part is intended to handle case #8 in `LocateSymbol.Ambiguous`, where you have a declaration of the form `Foo abcd("asdf");` which invokes a constructor.

A naive attempt to add this logic to `TargetFinder::add(const Decl*)` resulted in the constructor being a target even for //references// to the variable, not just its declaration.


================
Comment at: clang-tools-extra/clangd/XRefs.cpp:147
   }
+  while ((N = N->Parent)) {
+    if (N->ASTNode.get<CallExpr>() || N->ASTNode.get<ImplicitCastExpr>() ||
----------------
This part is a super hacky way to keep case #9 in `LocateSymbol.Ambiguous` passing while not regressing other tests.

In that case, the selection tree looks like this:

```
       DeclStmt Foo foox = Foo("asdf");

         VarDecl Foo foox = Foo("asdf")
           ExprWithCleanups Foo("asdf")
             CXXConstructExpr Foo("asdf")
               MaterializeTemporaryExpr Foo("asdf")
                 CXXFunctionalCastExpr Foo("asdf")
                  .RecordTypeLoc Foo
```

The common ancestor is the `RecordTypeLoc`, but we'd like to find the constructor referred to by the `CXXConstructExpr` as a target as well. To achieve that, my current code walks up the parent tree until we encounter a `CXXConstructExpr`, but aborts the walk if certain node types are encountered to avoid certain other scenarios where we have a `CXXConstructExpr` ancestor.

This is almost certainly wrong, as there are likely many other cases where we have a `CXXConstructExpr` ancestor but don't want to find the constructor as a target which are not being handled correctly.

Is there a better way to identify the syntactic form at issue in this testcase?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69237/new/

https://reviews.llvm.org/D69237