[Flang] Fix ASSIGN statement (llvm#149941)

Handle the case where the assigned variable also has a pointer
attribute.

Fixes llvm#121721

(cherry picked from commit fc0a978)

Author: ceseo

flang/lib/Lower/Bridge.cpp

@@ -5505,10 +5505,34 @@ class FirConverter : public Fortran::lower::AbstractConverter {
   void genFIR(const Fortran::parser::AssignStmt &stmt) {
     const Fortran::semantics::Symbol &symbol =
         *std::get<Fortran::parser::Name>(stmt.t).symbol;
+
     mlir::Location loc = toLocation();
+    mlir::Type symbolType = genType(symbol);
+    mlir::Value addr = getSymbolAddress(symbol);
+
+    // Handle the case where the assigned variable is declared as a pointer
+    if (auto eleTy = fir::dyn_cast_ptrOrBoxEleTy(symbolType)) {
+      if (auto ptrType = mlir::dyn_cast<fir::PointerType>(eleTy)) {
+        symbolType = ptrType.getEleTy();
+      } else {
+        symbolType = eleTy;
+      }
+    } else if (auto ptrType = mlir::dyn_cast<fir::PointerType>(symbolType)) {
+      symbolType = ptrType.getEleTy();
+    }
+
     mlir::Value labelValue = builder->createIntegerConstant(
-        loc, genType(symbol), std::get<Fortran::parser::Label>(stmt.t));
-    builder->create<fir::StoreOp>(loc, labelValue, getSymbolAddress(symbol));
+        loc, symbolType, std::get<Fortran::parser::Label>(stmt.t));
+
+    // If the address points to a boxed pointer, we need to dereference it
+    if (auto refType = mlir::dyn_cast<fir::ReferenceType>(addr.getType())) {
+      if (auto boxType = mlir::dyn_cast<fir::BoxType>(refType.getEleTy())) {
+        mlir::Value boxValue = builder->create<fir::LoadOp>(loc, addr);
+        addr = builder->create<fir::BoxAddrOp>(loc, boxValue);
+      }
+    }
+
+    builder->create<fir::StoreOp>(loc, labelValue, addr);
   }
 
   void genFIR(const Fortran::parser::FormatStmt &) {

flang/test/Lower/assign-statement.f90

@@ -0,0 +1,12 @@
+! RUN: bbc -emit-fir -o - %s | FileCheck %s
+
+  ! CHECK-LABEL: func @_QQmain
+  program main
+  integer :: ip
+  pointer :: ip
+
+  allocate(ip)
+  assign 10 to ip
+  ! CHECK: fir.store %c10_i32 to %11 : !fir.ptr<i32>
+  10 return
+  end program main