[gcc r13-8857] Fortran: fix ALLOCATE with SOURCE=, zero-length character [PR83865]

[Harald Anlauf via Gcc-cvs]

https://gcc.gnu.org/g:0530884fbf49cc81119d66de7e4a48b47172ed4c

commit r13-8857-g0530884fbf49cc81119d66de7e4a48b47172ed4c
Author: Harald Anlauf <anl...@gmx.de>
Date:   Mon Jun 3 22:02:06 2024 +0200

    Fortran: fix ALLOCATE with SOURCE=, zero-length character [PR83865]
    
    gcc/fortran/ChangeLog:
    
            PR fortran/83865
            * trans-stmt.cc (gfc_trans_allocate): Restrict special case for
            source-expression with zero-length character to rank 0, so that
            the array shape is not discarded.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/83865
            * gfortran.dg/allocate_with_source_32.f90: New test.
    
    (cherry picked from commit 7f21aee0d4ef95eee7d9f7f42e9a056715836648)

Diff:
---
 gcc/fortran/trans-stmt.cc                          |  3 +-
 .../gfortran.dg/allocate_with_source_32.f90        | 33 ++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/trans-stmt.cc b/gcc/fortran/trans-stmt.cc
index 35eb1880539b..caa7b59e9129 100644
--- a/gcc/fortran/trans-stmt.cc
+++ b/gcc/fortran/trans-stmt.cc
@@ -6398,8 +6398,9 @@ gfc_trans_allocate (gfc_code * code)
       else
        gfc_add_block_to_block (&post, &se.post);
 
-      /* Special case when string in expr3 is zero.  */
+      /* Special case when string in expr3 is scalar and has length zero.  */
       if (code->expr3->ts.type == BT_CHARACTER
+         && code->expr3->rank == 0
          && integer_zerop (se.string_length))
        {
          gfc_init_se (&se, NULL);
diff --git a/gcc/testsuite/gfortran.dg/allocate_with_source_32.f90 
b/gcc/testsuite/gfortran.dg/allocate_with_source_32.f90
new file mode 100644
index 000000000000..4a9bd46da4d5
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/allocate_with_source_32.f90
@@ -0,0 +1,33 @@
+! { dg-do run }
+!
+! PR fortran/83865
+!
+! Test ALLOCATE with SOURCE= of deferred length character, where
+! the source-expression is an array of character with length 0.
+
+program p
+  implicit none
+  character(:), allocatable :: z(:)
+  character(1) :: cc(4) = ""
+  allocate (z, source=[''])
+  if (len (z) /= 0 .or. size (z) /= 1) stop 1
+  deallocate (z)
+  allocate (z, source=['',''])
+  if (len (z) /= 0 .or. size (z) /= 2) stop 2
+  deallocate (z)
+  allocate (z, source=[ character(0) :: 'a','b','c'])
+  if (len (z) /= 0 .or. size (z) /= 3) stop 3
+  deallocate (z)
+  allocate (z, source=[ character(0) :: cc ])
+  if (len (z) /= 0 .or. size (z) /= 4) stop 4
+  deallocate (z)
+  associate (x => f())
+    if (len (x) /= 0 .or. size (x) /= 1) stop 5
+    if (x(1) /= '') stop 6
+  end associate
+contains
+  function f() result(z)
+    character(:), allocatable :: z(:)
+    allocate (z, source=[''])
+  end function f
+end