[gcc r12-4415] Fortran: generate error message for negative elements in SHAPE array

[Harald Anlauf <anlauf@gcc.gnu.org>]

https://gcc.gnu.org/g:b47490c572c5938f887b54240af6096a7c90f640

commit r12-4415-gb47490c572c5938f887b54240af6096a7c90f640
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Thu Oct 14 20:19:50 2021 +0200

    Fortran: generate error message for negative elements in SHAPE array
    
    gcc/fortran/ChangeLog:
    
            PR fortran/102717
            * simplify.c (gfc_simplify_reshape): Replace assert by error
            message for negative elements in SHAPE array.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/102717
            * gfortran.dg/reshape_shape_2.f90: New test.

Diff:
---
 gcc/fortran/simplify.c                        | 8 +++++++-
 gcc/testsuite/gfortran.dg/reshape_shape_2.f90 | 7 +++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index f40e4930b58..d675f2c3aef 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -6840,7 +6840,13 @@ gfc_simplify_reshape (gfc_expr *source, gfc_expr *shape_exp,
       gfc_extract_int (e, &shape[rank]);
 
       gcc_assert (rank >= 0 && rank < GFC_MAX_DIMENSIONS);
-      gcc_assert (shape[rank] >= 0);
+      if (shape[rank] < 0)
+	{
+	  gfc_error ("The SHAPE array for the RESHAPE intrinsic at %L has a "
+		     "negative value %d for dimension %d",
+		     &shape_exp->where, shape[rank], rank+1);
+	  return &gfc_bad_expr;
+	}
 
       rank++;
     }
diff --git a/gcc/testsuite/gfortran.dg/reshape_shape_2.f90 b/gcc/testsuite/gfortran.dg/reshape_shape_2.f90
new file mode 100644
index 00000000000..8f1757687bc
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/reshape_shape_2.f90
@@ -0,0 +1,7 @@
+! { dg-do compile }
+! PR fortran/102717
+
+program p
+  integer, parameter :: a(1) = 2
+  integer, parameter :: b(2) = reshape([3,4], -[a]) ! { dg-error "negative" }
+end