[flang] Support polymorphic source in RESHAPE intrinsic

[clementval]

Summary

Result must carry the polymorphic type information
from the source.

[PeteSteinfeld]

All builds and tests correctly and looks good.

flang/lib/Lower/IntrinsicCall.cpp

IntrinsicLibrary::genReshape(mlir::Type resultType,
   // Handle optional order argument
   mlir::Value order = isStaticallyAbsent(args[3])
                           ? builder.create<fir::AbsentOp>(
                                 loc, fir::BoxType::get(builder.getI1Type()))
                           : builder.createBox(loc, args[3]);
 
   // Create mutable fir.box to be passed to the runtime for the result.
   mlir::Type type = builder.getVarLenSeqTy(resultType, resultRank);
-  fir::MutableBoxValue resultMutableBox =
-      fir::factory::createTempMutableBox(builder, loc, type);
+  fir::MutableBoxValue resultMutableBox = fir::factory::createTempMutableBox(
+      builder, loc, type, {},
+      fir::isPolymorphicType(source.getType()) ? source : mlir::Value{});
 
   mlir::Value resultIrBox =
       fir::factory::getMutableIRBox(builder, loc, resultMutableBox);
 
   fir::runtime::genReshape(builder, loc, resultIrBox, source, shape, pad,
                            order);
 
   return readAndAddCleanUp(resultMutableBox, resultType, "RESHAPE");

flang/test/Lower/polymorphic-temp.f90

 ! CHECK: %[[C2_I64:.*]] = fir.convert %[[C2]] : (i32) -> i64
 ! CHECK: %{{.*}} = fir.call @_FortranASpread(%[[RES_BOX_NONE]], %[[P_BOX_NONE]], %[[C1]], %[[C2_I64]], %{{.*}}, %{{.*}}) fastmath<contract> : (!fir.ref<!fir.box<none>>, !fir.box<none>, i32, i64, !fir.ref<i8>, i32) -> none
 ! CHECK: %[[LOAD_RES:.*]] = fir.load %[[TEMP_RES]] : !fir.ref<!fir.class<!fir.heap<!fir.array<?xnone>>>>
 ! CHECK: %[[RES_ADDR:.*]] = fir.box_addr %[[LOAD_RES]] : (!fir.class<!fir.heap<!fir.array<?xnone>>>) -> !fir.heap<!fir.array<?xnone>>
 ! CHECK: %[[REBOX:.*]] = fir.rebox %[[LOAD_RES]] : (!fir.class<!fir.heap<!fir.array<?xnone>>>) -> !fir.class<!fir.array<?xnone>>
 ! CHECK: fir.call @_QMpoly_tmpPpass_unlimited_poly_1d(%[[REBOX]]) {{.*}} : (!fir.class<!fir.array<?xnone>>) -> ()
 ! CHECK: fir.freemem %[[RES_ADDR]] : !fir.heap<!fir.array<?xnone>>
 
+  subroutine test_temp_from_intrinsic_reshape(i)
+    class(*), allocatable :: a(:,:)
+    class(*), intent(in) :: i(20,20)
+    allocate(a(10,10), source=reshape(i,[10,10]))
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpoly_tmpPtest_temp_from_intrinsic_reshape(
+! CHECK-SAME: %[[I:.*]]: !fir.class<!fir.array<20x20xnone>> {fir.bindc_name = "i"}) {
+! CHECK: %[[TMP_RES:.*]] = fir.alloca !fir.class<!fir.heap<!fir.array<?x?xnone>>>
+! CHECK: %[[A:.*]] = fir.alloca !fir.class<!fir.heap<!fir.array<?x?xnone>>> {bindc_name = "a", uniq_name = "_QMpoly_tmpFtest_temp_from_intrinsic_reshapeEa"}
+! CHECK: %[[EMBOX_WITH_SOURCE:.*]] = fir.embox %{{.*}}(%{{.*}}) source_box %[[I]] : (!fir.heap<!fir.array<?x?xnone>>, !fir.shape<2>, !fir.class<!fir.array<20x20xnone>>) -> !fir.class<!fir.heap<!fir.array<?x?xnone>>>
+! CHECK: fir.store %[[EMBOX_WITH_SOURCE]] to %[[TMP_RES]] : !fir.ref<!fir.class<!fir.heap<!fir.array<?x?xnone>>>>
+! CHECK: %[[RES_BOX_NONE:.*]] = fir.convert %[[TMP_RES]] : (!fir.ref<!fir.class<!fir.heap<!fir.array<?x?xnone>>>>) -> !fir.ref<!fir.box<none>>
+! CHECK: %[[I_BOX_NONE:.*]] = fir.convert %[[I]] : (!fir.class<!fir.array<20x20xnone>>) -> !fir.box<none>
+! CHECK: %{{.*}} = fir.call @_FortranAReshape(%[[RES_BOX_NONE]], %[[I_BOX_NONE]], %{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}} : (!fir.ref<!fir.box<none>>, !fir.box<none>, !fir.box<none>, !fir.box<none>, !fir.box<none>, !fir.ref<i8>, i32) -> none
+! CHECK: %[[LOAD_RES:.*]] = fir.load %[[TMP_RES]] : !fir.ref<!fir.class<!fir.heap<!fir.array<?x?xnone>>>>
+! CHECK: %[[A_BOX_NONE:.*]] = fir.convert %[[A]] : (!fir.ref<!fir.class<!fir.heap<!fir.array<?x?xnone>>>>) -> !fir.ref<!fir.box<none>>
+! CHECK: %[[RES_BOX_NONE:.*]] = fir.convert %[[LOAD_RES]] : (!fir.class<!fir.heap<!fir.array<?x?xnone>>>) -> !fir.box<none>
+! CHECK: %{{.*}} = fir.call @_FortranAAllocatableApplyMold(%[[A_BOX_NONE]], %[[RES_BOX_NONE]]) {{.*}} : (!fir.ref<!fir.box<none>>, !fir.box<none>) -> none
+
 end module