Using associate to get length. Also modified the test to check for emboxchar.

Author: EbinJose2002

flang/lib/Optimizer/HLFIR/Transforms/BufferizeHLFIR.cpp

@@ -448,10 +448,9 @@ struct AssociateOpConversion
           sourceVar = builder.create<fir::BoxAddrOp>(loc, assocType, sourceVar);
         } else if (mlir::isa<fir::ReferenceType>(sourceVar.getType()) &&
                    mlir::isa<fir::BoxCharType>(assocType)) {
+          mlir::Value lenVal = associate.getTypeparams()[0];
           auto refTy = mlir::cast<fir::ReferenceType>(sourceVar.getType());
           auto charTy = mlir::dyn_cast<fir::CharacterType>(refTy.getEleTy());
-          mlir::Value lenVal = builder.createIntegerConstant(
-              loc, builder.getCharacterLengthType(), charTy.getLen());
           auto boxCharType =
               fir::BoxCharType::get(builder.getContext(), charTy.getFKind());
           sourceVar = builder.create<fir::EmboxCharOp>(loc, boxCharType,

flang/test/Lower/adjustr.f90

@@ -1,7 +1,9 @@
-! RUN: bbc -emit-fir -o - %s | FileCheck %s
+! RUN: %flang_fc1 -emit-fir -o - %s | FileCheck %s
 
 ! Checking no reference to boxchar conversion is in the emitted fir.
 ! CHECK-NOT: (!fir.ref<!fir.char<1,4>>) -> !fir.boxchar<1>
+! CHECK: %[[Const4:.*]] = arith.constant 4 : index
+! CHECK: fir.emboxchar
 
 program main
   logical         ,dimension(1):: mask = .true.