Corrected the wrong scope of the variables declared inside the Lambda function

Fixes vgvassilev#1701

Author: Vedant2005goyal

lib/Differentiator/ReverseModeVisitor.cpp

@@ -1823,9 +1823,11 @@ Expr* ReverseModeVisitor::getStdInitListSizeExpr(const Expr* E) {
             getCurrentScope(), DS));
 
     m_DerivativeFnScope = getCurrentScope();
+    Stmts OuterGlobals;
+    std::swap(m_Globals, OuterGlobals);
+
     beginBlock();
 
-    // FIXME: Fix m_Globals being emmitted to the outer function.
     StmtDiff BodyDiff = Visit(LE->getCallOperator()->getBody());
     for (auto* S : cast<CompoundStmt>(BodyDiff.getStmt())->body())
       addToCurrentBlock(S);
@@ -1834,6 +1836,19 @@ Expr* ReverseModeVisitor::getStdInitListSizeExpr(const Expr* E) {
 
     CompoundStmt* DerivedBody = endBlock();
 
+    if (!m_Globals.empty()) {
+      llvm::SmallVector<Stmt*, 32> NewBodyStmts;
+      NewBodyStmts.append(m_Globals.begin(), m_Globals.end());
+      NewBodyStmts.append(DerivedBody->body().begin(),
+                          DerivedBody->body().end());
+
+      DerivedBody = CompoundStmt::Create(
+          m_Sema.getASTContext(), NewBodyStmts, FPOptionsOverride(),
+          DerivedBody->getLBracLoc(), DerivedBody->getRBracLoc());
+    }
+    m_Globals.clear();
+    std::swap(m_Globals, OuterGlobals);
+
     Expr* lambda =
         m_Sema
             .ActOnLambdaExpr(

test/Regressions/issue-1701.cpp

@@ -0,0 +1,23 @@
+// RUN: %cladclang -std=c++17 -I%S/../../include %s -o %t
+// RUN: %t | %filecheck_exec %s
+// UNSUPPORTED: clang-10, clang-11, clang-12, clang-13, clang-14, clang-15, clang-16
+#include <cstdio>
+#include "clad/Differentiator/Differentiator.h"
+
+void f2(double i, double j){
+    auto _f = [] () {
+    {
+      double a = 1;
+    }
+  };
+}
+int main(){
+    auto diff=clad::gradient(f2);
+    double di=0,dj=0;
+    double i=7,j=7;
+    diff.execute(i,j,&di,&dj);
+
+    printf("Execution successful\n");
+    // CHECK-EXEC: Execution successful
+    return 0;
+}