From 443fcd8fe53c7769b54bb56975750780c8f3fab7 Mon Sep 17 00:00:00 2001
From: Vassil Vassilev <v.g.vassilev@gmail.com>
Date: Mon, 30 Dec 2024 18:27:34 +0000
Subject: [PATCH] Use CloneParmVarDecl and the parameters stored in the
 DiffRequest. NFC

---
 .../clad/Differentiator/ReverseModeVisitor.h  |  5 ----
 lib/Differentiator/ReverseModeVisitor.cpp     | 27 +++++++++----------
 2 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/include/clad/Differentiator/ReverseModeVisitor.h b/include/clad/Differentiator/ReverseModeVisitor.h
index 70a44f6aa..910b67c49 100644
--- a/include/clad/Differentiator/ReverseModeVisitor.h
+++ b/include/clad/Differentiator/ReverseModeVisitor.h
@@ -40,11 +40,6 @@ namespace clad {
     // several private/protected members of the visitor classes.
     friend class ErrorEstimationHandler;
     llvm::SmallVector<const clang::ValueDecl*, 16> m_IndependentVars;
-    /// Set used to keep track of parameter variables w.r.t which the
-    /// the derivative (gradient) is being computed. This is separate from the
-    /// m_Variables map because all other intermediate variables will
-    /// not be stored here.
-    std::unordered_set<const clang::ValueDecl*> m_ParamVarsWithDiff;
     /// In addition to a sequence of forward-accumulated Stmts (m_Blocks), in
     /// the reverse mode we also accumulate Stmts for the reverse pass which
     /// will be executed on return.
diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
index 5a935fb78..a0bcb252a 100644
--- a/lib/Differentiator/ReverseModeVisitor.cpp
+++ b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -1528,8 +1528,8 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
           // If the arg is used for differentiation of the function, then we
           // cannot free it in the end as it's the result to be returned to the
           // user.
-          if (m_ParamVarsWithDiff.find(DRE->getDecl()) ==
-              m_ParamVarsWithDiff.end())
+          if (std::find(m_DiffReq.DVI.begin(), m_DiffReq.DVI.end(),
+                        DRE->getDecl()) == m_DiffReq.DVI.end())
             DerivedCallArgs.push_back(ArgDiff.getExpr_dx());
         }
       }
@@ -4436,19 +4436,17 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     }
 
     for (auto* PVD : m_DiffReq->parameters()) {
-      auto* newPVD = utils::BuildParmVarDecl(
-          m_Sema, m_Derivative, PVD->getIdentifier(), PVD->getType(),
-          PVD->getStorageClass(), /*DefArg=*/nullptr, PVD->getTypeSourceInfo());
-      params.push_back(newPVD);
-
-      if (newPVD->getIdentifier())
-        m_Sema.PushOnScopeChains(newPVD, getCurrentScope(),
-                                 /*AddToContext=*/false);
-      else {
-        IdentifierInfo* newName = CreateUniqueIdentifier("arg");
-        newPVD->setDeclName(newName);
+      IdentifierInfo* PVDII = PVD->getIdentifier();
+      // Implicitly created special member functions have no parameter names.
+      if (!PVD->getDeclName())
+        PVDII = CreateUniqueIdentifier("arg");
+      auto* newPVD = CloneParmVarDecl(PVD, PVDII,
+                                      /*pushOnScopeChains=*/true,
+                                      /*cloneDefaultArg=*/false);
+      if (!PVD->getDeclName()) // We can't use lookup-based replacements
         m_DeclReplacements[PVD] = newPVD;
-      }
+
+      params.push_back(newPVD);
 
       auto* it = std::find(std::begin(diffParams), std::end(diffParams), PVD);
       if (it != std::end(diffParams)) {
@@ -4480,7 +4478,6 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
               m_Variables[*it] =
                   utils::BuildParenExpr(m_Sema, m_Variables[*it]);
           }
-          m_ParamVarsWithDiff.emplace(*it);
         }
       }
     }