fortran: Fix up initializers of param(0) PARAMETERs [PR103691]

On the gfortran.dg/pr103691.f90 testcase the Fortran ICE emits
  static real(kind=4) a[0] = {[0 ... -1]=2.0e+0};
That is an invalid RANGE_EXPR where the maximum is smaller than the minimum.

The following patch fixes that.  If TYPE_MAX_VALUE is smaller than
TYPE_MIN_VALUE, the array is empty and so doesn't need any initializer,
if the two are equal, we don't need to bother with a RANGE_EXPR and
can just use that INTEGER_CST as the index and finally for the 2+ values
in the range it uses a RANGE_EXPR as before.

2022-03-25  Jakub Jelinek  <jakub@redhat.com>

	PR fortran/103691
	* trans-array.cc (gfc_conv_array_initializer): If TYPE_MAX_VALUE is
	smaller than TYPE_MIN_VALUE (i.e. empty array), ignore the
	initializer; if TYPE_MIN_VALUE is equal to TYPE_MAX_VALUE, use just
	the TYPE_MIN_VALUE as index instead of RANGE_EXPR.

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index cfb6eac11c74c5bf075a646c6e42c47075541d7d..b3f8871ff22fff50c14b5cae7c49418f485c100a 100644 (file)
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -6267,10 +6267,17 @@ gfc_conv_array_initializer (tree type, gfc_expr * expr)
       else
        gfc_conv_structure (&se, expr, 1);
 
-      CONSTRUCTOR_APPEND_ELT (v, build2 (RANGE_EXPR, gfc_array_index_type,
-                                        TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
-                                        TYPE_MAX_VALUE (TYPE_DOMAIN (type))),
-                             se.expr);
+      if (tree_int_cst_lt (TYPE_MAX_VALUE (TYPE_DOMAIN (type)),
+                          TYPE_MIN_VALUE (TYPE_DOMAIN (type))))
+       break;
+      else if (tree_int_cst_equal (TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
+                                  TYPE_MAX_VALUE (TYPE_DOMAIN (type))))
+       range = TYPE_MIN_VALUE (TYPE_DOMAIN (type));
+      else
+       range = build2 (RANGE_EXPR, gfc_array_index_type,
+                       TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
+                       TYPE_MAX_VALUE (TYPE_DOMAIN (type)));
+      CONSTRUCTOR_APPEND_ELT (v, range, se.expr);
       break;
 
     case EXPR_ARRAY: