[flang] NORM2(DIM=) argument can't be dynamically optional

[klausler]

Summary

The intrinsic function table entry for NORM2 treats its DIM=
argument as if it can be dynamically optional; this is wrong,
and it should be treated in the same way as DIM= is for other
transformational intrinsic functions like SUM.

[PeteSteinfeld]

All builds and tests correctly and looks good.

flang/lib/Evaluate/intrinsics.cpp

static const IntrinsicInterface genericIntrinsicFunction[]{
     {"modulo", {{"a", OperandIntOrReal}, {"p", OperandIntOrReal}},
         OperandIntOrReal},
     {"nearest", {{"x", SameReal}, {"s", AnyReal}}, SameReal},
     {"new_line",
         {{"a", SameCharNoLen, Rank::anyOrAssumedRank, Optionality::required,
             common::Intent::In, {ArgFlag::canBeNull}}},
         SameCharNoLen, Rank::scalar, IntrinsicClass::inquiryFunction},
     {"nint", {{"a", AnyReal}, DefaultingKIND}, KINDInt},
-    {"norm2", {{"x", SameReal, Rank::array}, OptionalDIM}, SameReal,
+    {"norm2", {{"x", SameReal, Rank::array}, RequiredDIM}, SameReal,
         Rank::dimReduced, IntrinsicClass::transformationalFunction},
+    {"norm2", {{"x", SameReal, Rank::array}, MissingDIM}, SameReal,
+        Rank::scalar, IntrinsicClass::transformationalFunction},
     {"not", {{"i", SameInt}}, SameInt},
     // NULL() is a special case handled in Probe() below
     {"num_images", {}, DefaultInt, Rank::scalar,
         IntrinsicClass::transformationalFunction},
     {"num_images", {{"team", TeamType, Rank::scalar}}, DefaultInt, Rank::scalar,
         IntrinsicClass::transformationalFunction},
     {"num_images", {{"team_number", AnyInt, Rank::scalar}}, DefaultInt,
         Rank::scalar, IntrinsicClass::transformationalFunction},

flang/test/Semantics/dim01.f90

function f0b(a)
     !ERROR: The value of DIM= (2) may not be greater than 1
     f0b = sum(a,dim=2)
   end function
   function f1(a,d)
     real, intent(in) :: a(:)
     integer, optional, intent(in) :: d
     !PORTABILITY: The actual argument for DIM= is optional, pointer, or allocatable, and it is assumed to be present and equal to 1 at execution time
     f1 = sum(a,dim=d)
+    !PORTABILITY: The actual argument for DIM= is optional, pointer, or allocatable, and it is assumed to be present and equal to 1 at execution time
+    f1 = norm2(a,dim=d)
   end function
   function f2(a,d)
     real, intent(in) :: a(:)
     integer, pointer, intent(in) :: d
     !PORTABILITY: The actual argument for DIM= is optional, pointer, or allocatable, and it is assumed to be present and equal to 1 at execution time
     f2 = sum(a,dim=d)
   end function
   function f3(a,d)
function f10b(a)
     f10b = sum(a,dim=3)
   end function
   function f11(a,d)
     real, intent(in) :: a(:,:)
     integer, optional, intent(in) :: d
     real, allocatable :: f11(:)
     !WARNING: The actual argument for DIM= is optional, pointer, or allocatable, and may not be absent during execution; parenthesize to silence this warning
     f11 = sum(a,dim=d)
+    !WARNING: The actual argument for DIM= is optional, pointer, or allocatable, and may not be absent during execution; parenthesize to silence this warning
+    f11 = norm2(a,dim=d)
   end function
   function f12(a,d)
     real, intent(in) :: a(:,:)
     integer, pointer, intent(in) :: d
     real, allocatable :: f12(:)
     !WARNING: The actual argument for DIM= is optional, pointer, or allocatable, and may not be absent during execution; parenthesize to silence this warning
     f12 = sum(a,dim=d)
   end function
   function f13(a,d)
     real, intent(in) :: a(:,:)
     integer, allocatable, intent(in) :: d
     real, allocatable :: f13(:)
     !WARNING: The actual argument for DIM= is optional, pointer, or allocatable, and may not be absent during execution; parenthesize to silence this warning
     f13 = sum(a,dim=d)
   end function
 end module
-