gdb: make get_discrete_bounds return bool

get_discrete_bounds currently has three possible return values (see its
current doc for details).  It appears that for all callers, it would be
sufficient to have a boolean "worked" / "didn't work" return value.

Change the return type of get_discrete_bounds to bool and adjust all
callers.  Doing so simplifies the following patch.

gdb/ChangeLog:

	* gdbtypes.h (get_discrete_bounds): Return bool, adjust all
	callers.
	* gdbtypes.c (get_discrete_bounds): Return bool.

Change-Id: Ie51feee23c75f0cd7939742604282d745db59172

14 files changed, 58 insertions, 50 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 468bbca..e7f083c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2020-12-09  Simon Marchi  <simon.marchi@efficios.com>
 
+	* gdbtypes.h (get_discrete_bounds): Return bool, adjust all
+	callers.
+	* gdbtypes.c (get_discrete_bounds): Return bool.
+
+2020-12-09  Simon Marchi  <simon.marchi@efficios.com>
+
 	* ada-lang.c (ada_value_slice_from_ptr): Adjust.
 	(ada_value_slice): Adjust.
 	(pos_atr): Adjust.
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 5813ecd..5e2f1ec 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -2112,7 +2112,7 @@ constrained_packed_array_type (struct type *type, long *elt_bits)
 
   if ((check_typedef (index_type)->code () == TYPE_CODE_RANGE
        && is_dynamic_type (check_typedef (index_type)))
-      || get_discrete_bounds (index_type, &low_bound, &high_bound) < 0)
+      || !get_discrete_bounds (index_type, &low_bound, &high_bound))
     low_bound = high_bound = 0;
   if (high_bound < low_bound)
     *elt_bits = TYPE_LENGTH (new_type) = 0;
@@ -2182,7 +2182,7 @@ recursively_update_array_bitsize (struct type *type)
   gdb_assert (type->code () == TYPE_CODE_ARRAY);
 
   LONGEST low, high;
-  if (get_discrete_bounds (type->index_type (), &low, &high) < 0
+  if (!get_discrete_bounds (type->index_type (), &low, &high)
       || low > high)
     return 0;
   LONGEST our_len = high - low + 1;
@@ -2299,7 +2299,7 @@ value_subscript_packed (struct value *arr, int arity, struct value **ind)
 	  LONGEST lowerbound, upperbound;
 	  LONGEST idx;
 
-	  if (get_discrete_bounds (range_type, &lowerbound, &upperbound) < 0)
+	  if (!get_discrete_bounds (range_type, &lowerbound, &upperbound))
 	    {
 	      lim_warning (_("don't know bounds of array"));
 	      lowerbound = upperbound = 0;
diff --git a/gdb/ada-valprint.c b/gdb/ada-valprint.c
index 6ddb584..7d17f41 100644
--- a/gdb/ada-valprint.c
+++ b/gdb/ada-valprint.c
@@ -136,7 +136,7 @@ val_print_packed_array_elements (struct type *type, const gdb_byte *valaddr,
   {
     LONGEST high;
 
-    if (get_discrete_bounds (index_type, &low, &high) < 0)
+    if (!get_discrete_bounds (index_type, &low, &high))
       len = 1;
     else if (low > high)
       {
diff --git a/gdb/c-lang.c b/gdb/c-lang.c
index 2a17e00..c2db47e 100644
--- a/gdb/c-lang.c
+++ b/gdb/c-lang.c
@@ -698,8 +698,8 @@ evaluate_subexp_c (struct type *expect_type, struct expression *exp,
 		LONGEST low_bound, high_bound;
 		int element_size = TYPE_LENGTH (type);
 
-		if (get_discrete_bounds (expect_type->index_type (),
-					 &low_bound, &high_bound) < 0)
+		if (!get_discrete_bounds (expect_type->index_type (),
+					  &low_bound, &high_bound))
 		  {
 		    low_bound = 0;
 		    high_bound = (TYPE_LENGTH (expect_type) / element_size) - 1;
diff --git a/gdb/eval.c b/gdb/eval.c
index d02813e..5eb6ce1 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -1386,7 +1386,7 @@ evaluate_subexp_standard (struct type *expect_type,
 	  int element_size = TYPE_LENGTH (check_typedef (element_type));
 	  LONGEST low_bound, high_bound, index;
 
-	  if (get_discrete_bounds (range_type, &low_bound, &high_bound) < 0)
+	  if (!get_discrete_bounds (range_type, &low_bound, &high_bound))
 	    {
 	      low_bound = 0;
 	      high_bound = (TYPE_LENGTH (type) / element_size) - 1;
@@ -1426,7 +1426,7 @@ evaluate_subexp_standard (struct type *expect_type,
 		 || check_type->code () == TYPE_CODE_TYPEDEF)
 	    check_type = TYPE_TARGET_TYPE (check_type);
 
-	  if (get_discrete_bounds (element_type, &low_bound, &high_bound) < 0)
+	  if (!get_discrete_bounds (element_type, &low_bound, &high_bound))
 	    error (_("(power)set type with unknown size"));
 	  memset (valaddr, '\0', TYPE_LENGTH (type));
 	  for (tem = 0; tem < nargs; tem++)
diff --git a/gdb/f-array-walker.h b/gdb/f-array-walker.h
index 417f9f0..c202df6 100644
--- a/gdb/f-array-walker.h
+++ b/gdb/f-array-walker.h
@@ -42,7 +42,7 @@ public:
 
     /* Get the range, and extract the bounds.  */
     struct type *range_type = type->index_type ();
-    if (get_discrete_bounds (range_type, &m_lowerbound, &m_upperbound) < 0)
+    if (!get_discrete_bounds (range_type, &m_lowerbound, &m_upperbound))
       error ("unable to read array bounds");
 
     /* Figure out the stride for this array.  */
@@ -198,7 +198,7 @@ private:
     /* Extract the range, and get lower and upper bounds.  */
     struct type *range_type = check_typedef (type)->index_type ();
     LONGEST lowerbound, upperbound;
-    if (get_discrete_bounds (range_type, &lowerbound, &upperbound) < 0)
+    if (!get_discrete_bounds (range_type, &lowerbound, &upperbound))
       error ("failed to get range bounds");
 
     /* CALC is used to calculate the offsets for each element in this
diff --git a/gdb/f-lang.c b/gdb/f-lang.c
index 6771758..bbece50 100644
--- a/gdb/f-lang.c
+++ b/gdb/f-lang.c
@@ -1404,7 +1404,7 @@ fortran_adjust_dynamic_array_base_address_hack (struct type *type,
       tmp_type = check_typedef (tmp_type);
       struct type *range_type = tmp_type->index_type ();
       LONGEST lowerbound, upperbound, stride;
-      if (get_discrete_bounds (range_type, &lowerbound, &upperbound) < 0)
+      if (!get_discrete_bounds (range_type, &lowerbound, &upperbound))
 	error ("failed to get range bounds");
 
       /* Figure out the stride for this dimension.  */
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 0c91edd..f1b19b5 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -1036,15 +1036,9 @@ has_static_range (const struct range_bounds *bounds)
 	  && bounds->stride.kind () == PROP_CONST);
 }
 
+/* See gdbtypes.h.  */
 
-/* Set *LOWP and *HIGHP to the lower and upper bounds of discrete type
-   TYPE.
-
-   Return 1 if type is a range type with two defined, constant bounds.
-   Else, return 0 if it is discrete (and bounds will fit in LONGEST).
-   Else, return -1.  */
-
-int
+bool
 get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 {
   type = check_typedef (type);
@@ -1055,7 +1049,7 @@ get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 	 constant bounds.  */
       if (type->bounds ()->low.kind () != PROP_CONST
 	  || type->bounds ()->high.kind () != PROP_CONST)
-	return -1;
+	return false;
 
       *lowp = type->bounds ()->low.const_val ();
       *highp = type->bounds ()->high.const_val ();
@@ -1065,20 +1059,17 @@ get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 	  gdb::optional<LONGEST> low_pos
 	    = discrete_position (TYPE_TARGET_TYPE (type), *lowp);
 
-	  if (!low_pos.has_value ())
-	    return 0;
-
-	  *lowp = *low_pos;
+	  if (low_pos.has_value ())
+	    *lowp = *low_pos;
 
 	  gdb::optional<LONGEST> high_pos
 	    = discrete_position (TYPE_TARGET_TYPE (type), *highp);
 
-	  if (!high_pos.has_value ())
-	    return 0;
-
-	  *highp = *high_pos;
+	  if (high_pos.has_value ())
+	    *highp = *high_pos;
 	}
-      return 1;
+      return true;
+
     case TYPE_CODE_ENUM:
       if (type->num_fields () > 0)
 	{
@@ -1104,19 +1095,22 @@ get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 	  *lowp = 0;
 	  *highp = -1;
 	}
-      return 0;
+      return true;
+
     case TYPE_CODE_BOOL:
       *lowp = 0;
       *highp = 1;
-      return 0;
+      return true;
+
     case TYPE_CODE_INT:
       if (TYPE_LENGTH (type) > sizeof (LONGEST))	/* Too big */
-	return -1;
+	return false;
+
       if (!type->is_unsigned ())
 	{
 	  *lowp = -(1 << (TYPE_LENGTH (type) * TARGET_CHAR_BIT - 1));
 	  *highp = -*lowp - 1;
-	  return 0;
+	  return true;
 	}
       /* fall through */
     case TYPE_CODE_CHAR:
@@ -1126,9 +1120,10 @@ get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 	 if TYPE_LENGTH (type) == sizeof (LONGEST).  */
       *highp = 1 << (TYPE_LENGTH (type) * TARGET_CHAR_BIT - 1);
       *highp = (*highp - 1) | *highp;
-      return 0;
+      return true;
+
     default:
-      return -1;
+      return false;
     }
 }
 
@@ -1140,13 +1135,11 @@ get_array_bounds (struct type *type, LONGEST *low_bound, LONGEST *high_bound)
   struct type *index = type->index_type ();
   LONGEST low = 0;
   LONGEST high = 0;
-  int res;
 
   if (index == NULL)
     return false;
 
-  res = get_discrete_bounds (index, &low, &high);
-  if (res == -1)
+  if (!get_discrete_bounds (index, &low, &high))
     return false;
 
   if (low_bound)
@@ -1223,8 +1216,9 @@ update_static_array_size (struct type *type)
       if (stride == 0)
 	stride = range_type->bit_stride ();
 
-      if (get_discrete_bounds (range_type, &low_bound, &high_bound) < 0)
+      if (!get_discrete_bounds (range_type, &low_bound, &high_bound))
 	low_bound = high_bound = 0;
+
       element_type = check_typedef (TYPE_TARGET_TYPE (type));
       /* Be careful when setting the array length.  Ada arrays can be
 	 empty arrays with the high_bound being smaller than the low_bound.
@@ -1420,8 +1414,9 @@ create_set_type (struct type *result_type, struct type *domain_type)
     {
       LONGEST low_bound, high_bound, bit_length;
 
-      if (get_discrete_bounds (domain_type, &low_bound, &high_bound) < 0)
+      if (!get_discrete_bounds (domain_type, &low_bound, &high_bound))
 	low_bound = high_bound = 0;
+
       bit_length = high_bound - low_bound + 1;
       TYPE_LENGTH (result_type)
 	= (bit_length + TARGET_CHAR_BIT - 1) / TARGET_CHAR_BIT;
diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
index e304856..19d0740 100644
--- a/gdb/gdbtypes.h
+++ b/gdb/gdbtypes.h
@@ -2466,7 +2466,13 @@ extern struct type *lookup_template_type (const char *, struct type *,
 
 extern int get_vptr_fieldno (struct type *, struct type **);
 
-extern int get_discrete_bounds (struct type *, LONGEST *, LONGEST *);
+/* Set *LOWP and *HIGHP to the lower and upper bounds of discrete type
+   TYPE.
+
+   Return true if the two bounds are available, false otherwise.  */
+
+extern bool get_discrete_bounds (struct type *type, LONGEST *lowp,
+				 LONGEST *highp);
 
 /* Assuming TYPE is a simple, non-empty array type, compute its upper
    and lower bound.  Save the low bound into LOW_BOUND if not NULL.
diff --git a/gdb/m2-typeprint.c b/gdb/m2-typeprint.c
index 8fbcdf4..20a3d13 100644
--- a/gdb/m2-typeprint.c
+++ b/gdb/m2-typeprint.c
@@ -372,7 +372,7 @@ m2_is_long_set (struct type *type)
 			    This should be integrated into gdbtypes.c
 			    inside get_discrete_bounds.  */
 
-static int
+static bool
 m2_get_discrete_bounds (struct type *type, LONGEST *lowp, LONGEST *highp)
 {
   type = check_typedef (type);
@@ -419,7 +419,7 @@ m2_is_long_set_of_type (struct type *type, struct type **of_type)
       l1 = type->field (i).type ()->bounds ()->low.const_val ();
       h1 = type->field (len - 1).type ()->bounds ()->high.const_val ();
       *of_type = target;
-      if (m2_get_discrete_bounds (target, &l2, &h2) >= 0)
+      if (m2_get_discrete_bounds (target, &l2, &h2))
 	return (l1 == l2 && h1 == h2);
       error (_("long_set failed to find discrete bounds for its subtype"));
       return 0;
diff --git a/gdb/m2-valprint.c b/gdb/m2-valprint.c
index 96dc181..542fa49 100644
--- a/gdb/m2-valprint.c
+++ b/gdb/m2-valprint.c
@@ -97,7 +97,7 @@ m2_print_long_set (struct type *type, const gdb_byte *valaddr,
 
   target = TYPE_TARGET_TYPE (range);
 
-  if (get_discrete_bounds (range, &field_low, &field_high) >= 0)
+  if (get_discrete_bounds (range, &field_low, &field_high))
     {
       for (i = low_bound; i <= high_bound; i++)
 	{
@@ -137,7 +137,7 @@ m2_print_long_set (struct type *type, const gdb_byte *valaddr,
 	      if (field == len)
 		break;
 	      range = type->field (field).type ()->index_type ();
-	      if (get_discrete_bounds (range, &field_low, &field_high) < 0)
+	      if (!get_discrete_bounds (range, &field_low, &field_high))
 		break;
 	      target = TYPE_TARGET_TYPE (range);
 	    }
@@ -399,7 +399,7 @@ m2_language::value_print_inner (struct value *val, struct ui_file *stream,
 
 	  fputs_filtered ("{", stream);
 
-	  i = get_discrete_bounds (range, &low_bound, &high_bound);
+	  i = get_discrete_bounds (range, &low_bound, &high_bound) ? 0 : -1;
 	maybe_bad_bstring:
 	  if (i < 0)
 	    {
diff --git a/gdb/p-valprint.c b/gdb/p-valprint.c
index 428b2ef..8f785b7 100644
--- a/gdb/p-valprint.c
+++ b/gdb/p-valprint.c
@@ -343,7 +343,8 @@ pascal_value_print_inner (struct value *val, struct ui_file *stream,
 
 	  fputs_filtered ("[", stream);
 
-	  int bound_info = get_discrete_bounds (range, &low_bound, &high_bound);
+	  int bound_info = (get_discrete_bounds (range, &low_bound, &high_bound)
+			    ? 0 : -1);
 	  if (low_bound == 0 && high_bound == -1 && TYPE_LENGTH (type) > 0)
 	    {
 	      /* If we know the size of the set type, we can figure out the
diff --git a/gdb/valarith.c b/gdb/valarith.c
index 5b2bf18..077bcb4 100644
--- a/gdb/valarith.c
+++ b/gdb/valarith.c
@@ -1949,7 +1949,7 @@ value_bit_index (struct type *type, const gdb_byte *valaddr, int index)
   unsigned rel_index;
   struct type *range = type->index_type ();
 
-  if (get_discrete_bounds (range, &low_bound, &high_bound) < 0)
+  if (!get_discrete_bounds (range, &low_bound, &high_bound))
     return -2;
   if (index < low_bound || index > high_bound)
     return -1;
diff --git a/gdb/valops.c b/gdb/valops.c
index 4d0e002..09e97d2 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -453,7 +453,7 @@ value_cast (struct type *type, struct value *arg2)
 	  int val_length = TYPE_LENGTH (type2);
 	  LONGEST low_bound, high_bound, new_length;
 
-	  if (get_discrete_bounds (range_type, &low_bound, &high_bound) < 0)
+	  if (!get_discrete_bounds (range_type, &low_bound, &high_bound))
 	    low_bound = 0, high_bound = 0;
 	  new_length = val_length / element_length;
 	  if (val_length % element_length != 0)
@@ -3948,7 +3948,7 @@ value_slice (struct value *array, int lowbound, int length)
     error (_("array not associated"));
 
   range_type = array_type->index_type ();
-  if (get_discrete_bounds (range_type, &lowerbound, &upperbound) < 0)
+  if (!get_discrete_bounds (range_type, &lowerbound, &upperbound))
     error (_("slice from bad array or bitstring"));
 
   if (lowbound < lowerbound || length < 0