Fortran: fix passing of zero-sized array arguments to procedures [PR86277]

gcc/fortran/ChangeLog:

	PR fortran/86277
	* trans-array.cc (gfc_trans_allocate_array_storage): When passing a
	zero-sized array with fixed (= non-dynamic) size, allocate temporary
	by the caller, not by the callee.

gcc/testsuite/ChangeLog:

	PR fortran/86277
	* gfortran.dg/zero_sized_14.f90: New test.
	* gfortran.dg/zero_sized_15.f90: New test.

Co-authored-by: Mikael Morin <mikael@gcc.gnu.org>

3 files changed, 296 insertions, 1 deletions

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index e1c75e9..e7c51ba 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -1117,7 +1117,7 @@ gfc_trans_allocate_array_storage (stmtblock_t * pre, stmtblock_t * post,
 
   desc = info->descriptor;
   info->offset = gfc_index_zero_node;
-  if (size == NULL_TREE || integer_zerop (size))
+  if (size == NULL_TREE || (dynamic && integer_zerop (size)))
     {
       /* A callee allocated array.  */
       gfc_conv_descriptor_data_set (pre, desc, null_pointer_node);
diff --git a/gcc/testsuite/gfortran.dg/zero_sized_14.f90 b/gcc/testsuite/gfortran.dg/zero_sized_14.f90
new file mode 100644
index 0000000..32c7ae2
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/zero_sized_14.f90
@@ -0,0 +1,181 @@
+! { dg-do run }
+! PR fortran/86277
+!
+! Check proper detection of presence of optional array dummy arguments
+! for zero-sized actual array arguments or array constructors:
+! tests for REAL (as non-character intrinsic type) and empty derived type
+
+program test
+  implicit none
+  real, parameter   :: m(0) = 42.
+  real, parameter   :: n(1) = 23.
+  real              :: x(0) = 1.
+  real              :: z(1) = 2.
+  real              :: w(0)
+  real, pointer     :: p(:)
+  real, allocatable :: y(:)
+  integer           :: k = 0, l = 0     ! Test/failure counter
+  type dt
+     ! Empty type
+  end type dt
+  type(dt), parameter   :: t0(0) = dt()
+  type(dt), parameter   :: t1(1) = dt()
+  type(dt)              :: t2(0) = dt()
+  type(dt)              :: t3(1) = dt()
+  type(dt)              :: t4(0)
+  type(dt), allocatable :: tt(:)
+  !
+  allocate (p(0))
+  allocate (y(0))
+  allocate (tt(0))
+  call a0 ()
+  call a1 ()
+  call a2 ()
+  call a3 ()
+  call all_missing ()
+  print *, "Total tests:", k, " failed:", l
+contains
+  subroutine a0 ()
+    print *, "Variables as actual argument"
+    call i  (m)
+    call i  (n)
+    call i  (x)
+    call i  (w)
+    call i  (y)
+    call i  (p)
+    call j  (t0)
+    call j  (t1)
+    call j  (t2)
+    call j  (t3)
+    call j  (t4)
+    call j  (tt)
+    print *, "Array section as actual argument"
+    call i  (m(1:0))
+    call i  (n(1:0))
+    call i  (x(1:0))
+    call i  (w(1:0))
+    call i  (z(1:0))
+    call i  (p(1:0))
+    call j  (t0(1:0))
+    call j  (t1(1:0))
+    call j  (t2(1:0))
+    call j  (t3(1:0))
+    call j  (t4(1:0))
+    call j  (tt(1:0))
+  end subroutine a0
+  !
+  subroutine a1 ()
+    print *, "Explicit temporary as actual argument"
+    call i ((m))
+    call i ((n))
+    call i ((n(1:0)))
+    call i ((x))
+    call i ((w))
+    call i ((z(1:0)))
+    call i ((y))
+    call i ((p))
+    call i ((p(1:0)))
+    call j ((t0))
+    call j ((t1))
+    call j ((tt))
+    call j ((t1(1:0)))
+    call j ((tt(1:0)))
+  end subroutine a1
+  !
+  subroutine a2 ()
+    print *, "Array constructor as actual argument"
+    call i ([m])
+    call i ([n])
+    call i ([x])
+    call i ([w])
+    call i ([z])
+    call i ([m(1:0)])
+    call i ([n(1:0)])
+    call i ([m,n(1:0)])
+    call i ([x(1:0)])
+    call i ([w(1:0)])
+    call i ([z(1:0)])
+    call i ([y])
+    call i ([p])
+    call i ([y,y])
+    call i ([p,p])
+    call i ([y(1:0)])
+    call i ([p(1:0)])
+    call j ([t0])
+    call j ([t0,t0])
+    call j ([t1])
+    call j ([tt])
+    call j ([tt,tt])
+    call j ([t1(1:0)])
+    call j ([tt(1:0)])
+  end subroutine a2
+  !
+  subroutine a3 ()
+    print *, "Array constructor with type-spec as actual argument"
+    call i ([real::  ])
+    call i ([real:: 7])
+    call i ([real:: m])
+    call i ([real:: n])
+    call i ([real:: x])
+    call i ([real:: w])
+    call i ([real:: m(1:0)])
+    call i ([real:: n(1:0)])
+    call i ([real:: m,n(1:0)])
+    call i ([real:: x(1:0)])
+    call i ([real:: w(1:0)])
+    call i ([real:: z(1:0)])
+    call i ([real:: y])
+    call i ([real:: p])
+    call i ([real:: y,y])
+    call i ([real:: p,p])
+    call i ([real:: y(1:0)])
+    call i ([real:: p(1:0)])
+    call j ([ dt ::   ])
+    call j ([ dt :: t0])
+    call j ([ dt :: t0,t0])
+    call j ([ dt :: t1])
+    call j ([ dt :: tt])
+    call j ([ dt :: tt,tt])
+    call j ([ dt :: t1(1:0)])
+    call j ([ dt :: tt(1:0)])
+  end subroutine a3
+  !
+  subroutine i (arg)
+    real, optional, intent(in) :: arg(:)
+    logical :: t
+    t = present (arg)
+    k = k + 1
+    print *, 'test', k, merge ("  ok", "FAIL", t)
+    if (.not. t) l = l + 1
+    if (.not. t) stop k
+  end subroutine i
+  !
+  subroutine j (arg)
+    type(dt), optional, intent(in) :: arg(:)
+    logical :: t
+    t = present (arg)
+    k = k + 1
+    print *, 'test', k, merge ("  ok", "FAIL", t)
+    if (.not. t) l = l + 1
+    if (.not. t) stop k
+  end subroutine j
+  !
+  subroutine all_missing (arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8)
+    real,         optional, intent(in)  :: arg1(:)
+    real,         optional, allocatable :: arg2(:)
+    real,         optional, pointer     :: arg3(:)
+    character(*), optional, intent(in)  :: arg4(:)
+    character(*), optional, allocatable :: arg5(:)
+    character(*), optional, pointer     :: arg6(:)
+    character(:), optional, pointer     :: arg7(:)
+    character(:), optional, allocatable :: arg8(:)
+    if (present (arg1)) stop 101
+    if (present (arg2)) stop 102
+    if (present (arg3)) stop 103
+    if (present (arg4)) stop 104
+    if (present (arg5)) stop 105
+    if (present (arg6)) stop 106
+    if (present (arg7)) stop 107
+    if (present (arg8)) stop 108
+  end subroutine all_missing
+end program
diff --git a/gcc/testsuite/gfortran.dg/zero_sized_15.f90 b/gcc/testsuite/gfortran.dg/zero_sized_15.f90
new file mode 100644
index 0000000..c7d12ae
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/zero_sized_15.f90
@@ -0,0 +1,114 @@
+! { dg-do run }
+! PR fortran/86277
+!
+! Check proper detection of presence of optional array dummy arguments
+! for zero-sized actual array arguments or array constructors:
+! tests for CHARACTER
+
+program test
+  implicit none
+  character(0), parameter   :: c0(0) = ""
+  character(0), parameter   :: c1(1) = ""
+  character(1), parameter   :: d0(0) = ""
+  character(1), parameter   :: d1(1) = ""
+  character(0)              :: w0(0)
+  character(0)              :: w1(1)
+  character(:), allocatable :: cc(:)
+  integer                   :: k = 0, l = 0     ! Test/failure counter
+  !
+  allocate (character(0) :: cc(0))
+  call a0 ()
+  call a1 ()
+  call a2 ()
+  call a3 ()
+  print *, "Total tests:", k, " failed:", l
+contains
+  subroutine a0 ()
+    print *, "Variables as actual argument"
+    call i  (c0)
+    call i  (c1)
+    call i  (d0)
+    call i  (d1)
+    call i  (w0)
+    call i  (w1)
+    call i  (cc)
+    print *, "Array section as actual argument"
+    call i  (c1(1:0))
+    call i  (c1(1:0)(1:0))
+    call i  (w1(1:0))
+    call i  (w1(1:0)(1:0))
+    call i  (cc(1:0))
+    call i  (cc(1:0)(1:0))
+  end subroutine a0
+  !
+  subroutine a1 ()
+    print *, "Explicit temporary as actual argument"
+    call i ((c0))
+    call i ((c1))
+    call i ((d0))
+    call i ((d1))
+    call i ((w0))
+    call i ((w1))
+    call i ((cc))
+    call i ((c1(1:0)))
+    call i ((c1(1:0)(1:0)))
+    call i ((w1(1:0)))
+    call i ((w1(1:0)(1:0)))
+    call i ((cc(1:0)))
+    call i ((cc(1:0)(1:0)))
+  end subroutine a1
+  !
+  subroutine a2 ()
+    print *, "Array constructor as actual argument"
+    call i ([c0])
+    call i ([c1])
+    call i ([d0])
+    call i ([d1])
+    call i ([w0])
+    call i ([w1])
+    call i ([cc])
+    call i ([c0,c0])
+    call i ([c1,c1])
+    call i ([d0,d0])
+    call i ([cc,cc])
+    call i ([c1(1:0)])
+    call i ([c1(1:0)(1:0)])
+    call i ([w1(1:0)])
+    call i ([w1(1:0)(1:0)])
+    call i ([cc(1:0)])
+    call i ([cc(1:0)(1:0)])
+  end subroutine a2
+  !
+  subroutine a3 ()
+    print *, "Array constructor with type-spec as actual argument"
+    call i ([character(0) ::   ])
+    call i ([character(0) :: ""])
+    call i ([character(0) :: c0])
+    call i ([character(0) :: c1])
+    call i ([character(0) :: d0])
+    call i ([character(0) :: d1])
+    call i ([character(0) :: w0])
+    call i ([character(0) :: w1])
+    call i ([character(0) :: cc])
+    call i ([character(0) :: c0,c0])
+    call i ([character(0) :: c1,c1])
+    call i ([character(0) :: d0,d0])
+    call i ([character(0) :: cc,cc])
+    call i ([character(0) :: c1(1:0)])
+    call i ([character(0) :: c1(1:0)(1:0)])
+    call i ([character(0) :: w1(1:0)])
+    call i ([character(0) :: w1(1:0)(1:0)])
+    call i ([character(0) :: cc(1:0)])
+    call i ([character(0) :: cc(1:0)(1:0)])
+  end subroutine a3
+  !
+  subroutine i(arg)
+    character(*), optional, intent(in) :: arg(:)
+    logical :: t
+    t = present (arg)
+    k = k + 1
+    print *, 'test', k, merge ("  ok", "FAIL", t)
+    if (.not. t) l = l + 1
+    if (.not. t) stop k
+  end subroutine i
+end program