[gcc r12-5842] Fortran: dimensions of an array have to be non-negative

[Harald Anlauf]

https://gcc.gnu.org/g:5f7cdea34e118776d0ccd2ff3dda0f5acab18a94

commit r12-5842-g5f7cdea34e118776d0ccd2ff3dda0f5acab18a94
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Tue Dec 7 23:06:41 2021 +0100

    Fortran: dimensions of an array have to be non-negative
    
    gcc/fortran/ChangeLog:
    
            PR fortran/103610
            * array.c (spec_dimen_size): Fix simplification of SHAPE:
            dimensions must be non-negative.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/103610
            * gfortran.dg/shape_11.f90: New test.

Diff:
---
 gcc/fortran/array.c                    |  6 ++++--
 gcc/testsuite/gfortran.dg/shape_11.f90 | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/array.c b/gcc/fortran/array.c
index e5e22099405..e4891dfef77 100644
--- a/gcc/fortran/array.c
+++ b/gcc/fortran/array.c
@@ -2296,8 +2296,7 @@ gfc_copy_iterator (gfc_iterator *src)
 /********* Subroutines for determining the size of an array *********/
 
 /* These are needed just to accommodate RESHAPE().  There are no
-   diagnostics here, we just return a negative number if something
-   goes wrong.  */
+   diagnostics here, we just return false if something goes wrong.  */
 
 
 /* Get the size of single dimension of an array specification.  The
@@ -2330,6 +2329,9 @@ spec_dimen_size (gfc_array_spec *as, int dimen, mpz_t *result)
 
   mpz_add_ui (*result, *result, 1);
 
+  if (mpz_cmp_si (*result, 0) < 0)
+    mpz_set_si (*result, 0);
+
   return true;
 }
 
diff --git a/gcc/testsuite/gfortran.dg/shape_11.f90 b/gcc/testsuite/gfortran.dg/shape_11.f90
new file mode 100644
index 00000000000..127d221e710
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/shape_11.f90
@@ -0,0 +1,16 @@
+! { dg-do compile }
+! { dg-options "-fdump-tree-original" }
+! PR fortran/103610 - ICE while simplifying SHAPE
+! Contributed by G.Steinmetz
+
+program p
+  integer, parameter :: a(-1) = 1
+  integer, parameter :: b(1)  = maskl(shape(a))
+  integer, parameter :: c(1)  = shape(a)
+  integer, parameter :: d(1)  = maskr(shape(a))
+  if (b(1) /= 0) stop 1
+  if (c(1) /= 0) stop 2
+  if (d(1) /= 0) stop 3
+end
+
+! { dg-final { scan-tree-dump-not "_gfortran_stop_numeric" "original" } }