[Bug fortran/99840] [9/10/11 Regression] ICE in gfc_simplify_matmul, at fortran/simplify.c:4777

[anlauf at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99840

--- Comment #5 from anlauf at gcc dot gnu.org ---
OK, now I see it.  gfc_get_shape does not init the resulting shape.
The following simpler patch does the job:

diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index 388aca7c38c..c27b47aa98f 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -8123,8 +8123,8 @@ gfc_simplify_transpose (gfc_expr *matrix)
                               &matrix->where);
   result->rank = 2;
   result->shape = gfc_get_shape (result->rank);
-  mpz_set (result->shape[0], matrix->shape[1]);
-  mpz_set (result->shape[1], matrix->shape[0]);
+  mpz_init_set (result->shape[0], matrix->shape[1]);
+  mpz_init_set (result->shape[1], matrix->shape[0]);

   if (matrix->ts.type == BT_CHARACTER)
     result->ts.u.cl = matrix->ts.u.cl;