[Patch] Fortran: Fix SHAPE for zero-size arrays

[Patch] Fortran: Fix SHAPE for zero-size arrays

[Tobias Burnus]

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That is for https://gcc.gnu.org/PR115150 – a GCC 12/13/14/15 regression, 
caused when switching from a libgomp call to inline code and missing the 
corner case of zero-size arrays ...

OK for mainline + all affected branches?

Tobias

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Fortran: Fix SHAPE for zero-size arrays

	PR fortran/115150

gcc/fortran/ChangeLog:

	* trans-intrinsic.cc (gfc_conv_intrinsic_bound): Fix SHAPE
	for zero-size arrays

gcc/testsuite/ChangeLog:

	* gfortran.dg/shape_12.f90: New test.

 gcc/fortran/trans-intrinsic.cc         |  4 ++-
 gcc/testsuite/gfortran.dg/shape_12.f90 | 51 ++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/trans-intrinsic.cc b/gcc/fortran/trans-intrinsic.cc
index 80dc3426ab0..912c1000e18 100644
--- a/gcc/fortran/trans-intrinsic.cc
+++ b/gcc/fortran/trans-intrinsic.cc
@@ -3090,7 +3090,9 @@ gfc_conv_intrinsic_bound (gfc_se * se, gfc_expr * expr, enum gfc_isym_id op)
 				      lbound, gfc_index_one_node);
 	}
       else if (op == GFC_ISYM_SHAPE)
-	se->expr = size;
+	se->expr = fold_build2_loc (input_location, MAX_EXPR,
+				    gfc_array_index_type, size,
+				    gfc_index_zero_node);
       else
 	gcc_unreachable ();
 
diff --git a/gcc/testsuite/gfortran.dg/shape_12.f90 b/gcc/testsuite/gfortran.dg/shape_12.f90
new file mode 100644
index 00000000000..e672e1ff9f9
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/shape_12.f90
@@ -0,0 +1,51 @@
+! { dg-do run }
+!
+! PR fortran/115150
+!
+! Check that SHAPE handles zero-sized arrays correctly
+!
+implicit none
+call one
+call two
+
+contains
+
+subroutine one
+  real,allocatable :: A(:),B(:,:)
+  allocate(a(3:0), b(5:1, 2:5))
+
+  if (any (shape(a) /= [0])) stop 1
+  if (any (shape(b) /= [0, 4])) stop 2
+  if (size(a) /= 0) stop 3
+  if (size(b) /= 0) stop 4
+  if (any (lbound(a) /= [1])) stop 5
+  if (any (lbound(b) /= [1, 2])) stop 6
+  if (any (ubound(a) /= [0])) stop 5
+  if (any (ubound(b) /= [0,5])) stop 6
+end
+
+subroutine two
+integer :: x1(10), x2(10,10)
+call f(x1, x2, -3)
+end
+
+subroutine f(y1, y2, n)
+  integer, value :: n
+  integer :: y1(1:n)
+  integer :: y2(1:n,4,2:*)
+  call g(y1, y2)
+end
+
+subroutine g(z1, z2)
+  integer :: z1(..), z2(..)
+
+  if (any (shape(z1) /= [0])) stop 1
+  if (any (shape(z2) /= [0, 4, -1])) stop 2
+  if (size(z1) /= 0) stop 3
+  if (size(z2) /= 0) stop 4
+  if (any (lbound(z1) /= [1])) stop 5
+  if (any (lbound(z2) /= [1, 1, 1])) stop 6
+  if (any (ubound(z1) /= [0])) stop 5
+  if (any (ubound(z2) /= [0, 4, -1])) stop 6
+end
+end

Re: [Patch] Fortran: Fix SHAPE for zero-size arrays

[FX Coudert]

Hi Tobias,

> That is for https://gcc.gnu.org/PR115150 – a GCC 12/13/14/15 regression, caused when switching from a libgomp call to inline code and missing the corner case of zero-size arrays …

OK to push, thanks.

FX