[flang] Catch obscure structure constructor error

[klausler]

Summary

A scalar value in a structure constructor may correspond to an
array component in the derived type only when that component has
a shape to which the scalar value may be expanded.

flang/lib/Semantics/expression.cpp

if (symbol) {
                     *symbol);
               } else {
                 auto checked{
                     CheckConformance(messages, *componentShape, *valueShape,
                         CheckConformanceFlags::RightIsExpandableDeferred,
                         "component", "value")};
                 if (checked && *checked && GetRank(*componentShape) > 0 &&
                     GetRank(*valueShape) == 0 &&
+                    (IsDeferredShape(*symbol) ||
                         !IsExpandableScalar(*converted, GetFoldingContext(),
-                        *componentShape, true /*admit PURE call*/)) {
+                            *componentShape, true /*admit PURE call*/))) {
                   AttachDeclaration(
                       Say(expr.source,
                           "Scalar value cannot be expanded to shape of array component '%s'"_err_en_US,
                           symbol->name()),
                       *symbol);
                 }
                 if (checked.value_or(true)) {
                   result.Add(*symbol, std::move(*converted));

flang/test/Semantics/data01.f90

 ! RUN: %python %S/test_errors.py %s %flang_fc1
 !Test for checking data constraints, C882-C887
 module m1
   type person
     integer :: age
     character(len=25) :: name
   end type
   integer, parameter::digits(5) = ( /-11,-22,-33,44,55/ )
   integer ::notConstDigits(5)
   real, parameter::numbers(5) = ( /-11.11,-22.22,-33.33,44.44,55.55/ )
   integer, parameter :: repeat = -1
   integer :: myAge = 2
   type(person) associated
   type hasAlloc
-    integer, allocatable :: a(:)
+    integer, allocatable :: a
   end type
 end
 
 subroutine CheckRepeat
   use m1
   type(person) myName(6)
   !C882
   !ERROR: Missing initialization for parameter 'uninitialized'

flang/test/Semantics/structconst06.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Don't expand scalars for allocatable components.
+module m
+  type t
+    real, allocatable :: a(:)
+  end type
+  !ERROR: Scalar value cannot be expanded to shape of array component 'a'
+  type(t) :: x = t(0.)
+end module