[flang] Change internal errors in RESHAPE runtime routine to user errors

[PeteSteinfeld]

Summary

There are several checks in the runtime routine for the RESHAPE
intrinsic. Some checks verify things that should have been checked at
compile time while others represent user errors.

This update changes the checks for user errors into calls to "Crash"
which include information about the failing check. This identifies them
as user errors rather than compiler errors.

I also verified that the checks that remain as internal errors are also
checked by the front end. I added a test to the front end's RESHAPE
test to complete the checks.

flang/runtime/transformational.cpp

void RTNAME(Reshape)(Descriptor &result, const Descriptor &source,
   // Extract and check the shape of the result; compute its element count.
   SubscriptValue resultExtent[maxRank];
   std::size_t shapeElementBytes{shape.ElementBytes()};
   std::size_t resultElements{1};
   SubscriptValue shapeSubscript{shape.GetDimension(0).LowerBound()};
   for (SubscriptValue j{0}; j < resultRank; ++j, ++shapeSubscript) {
     resultExtent[j] = GetInt64(
         shape.Element<char>(&shapeSubscript), shapeElementBytes, terminator);
-    RUNTIME_CHECK(terminator, resultExtent[j] >= 0);
+    if (resultExtent[j] < 0)
+      terminator.Crash(
+          "RESHAPE: bad value for SHAPE(%d)=%d", j + 1, resultExtent[j]);
     resultElements *= resultExtent[j];
   }
 
   // Check that there are sufficient elements in the SOURCE=, or that
   // the optional PAD= argument is present and nonempty.
   std::size_t elementBytes{source.ElementBytes()};
   std::size_t sourceElements{source.Elements()};
   std::size_t padElements{pad ? pad->Elements() : 0};
   if (resultElements > sourceElements) {
-    RUNTIME_CHECK(terminator, padElements > 0);
+    if (padElements <= 0)
+      terminator.Crash("RESHAPE: not eough elements, need %d but only have %d",
+          resultElements, sourceElements);
     RUNTIME_CHECK(terminator, pad->ElementBytes() == elementBytes);
   }
 
   // Extract and check the optional ORDER= argument, which must be a
   // permutation of [1..resultRank].
   int dimOrder[maxRank];
   if (order) {
     RUNTIME_CHECK(terminator, order->rank() == 1);
     RUNTIME_CHECK(terminator, order->type().IsInteger());
-    RUNTIME_CHECK(terminator, order->GetDimension(0).Extent() == resultRank);
+    if (order->GetDimension(0).Extent() != resultRank)
+      terminator.Crash("RESHAPE: the extent of ORDER (%d) must match the rank"
+                       " of the SHAPE (%d)",
+          order->GetDimension(0).Extent(), resultRank);
     std::uint64_t values{0};
     SubscriptValue orderSubscript{order->GetDimension(0).LowerBound()};
     std::size_t orderElementBytes{order->ElementBytes()};
     for (SubscriptValue j{0}; j < resultRank; ++j, ++orderSubscript) {
       auto k{GetInt64(order->Element<char>(&orderSubscript), orderElementBytes,
           terminator)};
-      RUNTIME_CHECK(
-          terminator, k >= 1 && k <= resultRank && !((values >> k) & 1));
+      if (k < 1 || k > resultRank || ((values >> k) & 1))
+        terminator.Crash("RESHAPE: bad value for ORDER element (%d)", k);
       values |= std::uint64_t{1} << k;
       dimOrder[j] = k - 1;
     }
   } else {
     for (int j{0}; j < resultRank; ++j) {
       dimOrder[j] = j;
     }
   }

flang/test/Semantics/reshape.f90

program reshaper
   real :: array13(2,3) = RESHAPE([(n, n = 1, 4)], [2, 3], [99], [1, 1])
 
   ! Examples that have caused problems
   integer :: array14(0,0,0) = RESHAPE([(n,n=1,0)],[0,0,0])
   integer, parameter :: array15(1) = RESHAPE([(n,n=1,2)],[1])
   integer, parameter :: array16(1) = RESHAPE([(n,n=1,8)],[1], [0], array15)
   integer, parameter, dimension(3,4) :: array17 = 3
   integer, parameter, dimension(3,4) :: array18 = RESHAPE(array17, [3,4])
+  integer, parameter, dimension(2,2) :: bad_order = reshape([1, 2, 3, 4], [2,2])
+  real :: array20(2,3)
   ! Implicit reshape of array of components
   type :: dType
     integer :: field(2)
   end type dType
   type(dType), parameter :: array19(*) = [dType::dType(field=[1,2])]
   logical, parameter :: lVar = all(array19(:)%field(1) == [2])
 
   !ERROR: Size of 'shape=' argument must not be greater than 15
   CALL ext_sub(RESHAPE([(n, n=1,20)], &
     [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]))
   !ERROR: 'shape=' argument must not have a negative extent
   CALL ext_sub(RESHAPE([(n, n=1,20)], [1, -5, 3]))
+  !ERROR: 'order=' argument has unacceptable rank 2
+  array20 = RESHAPE([(n, n = 1, 4)], [2, 3], order = bad_order)
 end program reshaper