gdb: Convert enum range_type to a bit field enum

The expression range_type enum represents the following ideas:

  - Lower bound is set to default,
  - Upper bound is set to default,
  - Upper bound is exclusive.

There are currently 6 entries in the enum to represent the combination
of all those ideas.

In a future commit I'd like to add stride information to the range,
this could in theory appear with any of the existing enum entries, so
this would take us to 12 enum entries.

This feels like its getting a little out of hand, so in this commit I
switch the range_type enum over to being a flags style enum.  There's
one entry to represent no flags being set, then 3 flags to represent
the 3 ideas above.  Adding stride information will require adding only
one more enum flag.

I've then gone through and updated the code to handle this change.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* expprint.c (print_subexp_standard): Update to reflect changes to
	enum range_type.
	(dump_subexp_body_standard): Likewise.
	* expression.h (enum range_type): Convert to a bit field enum, and
	make the enum unsigned.
	* f-exp.y (subrange): Update to reflect changes to enum
	range_type.
	* f-lang.c (value_f90_subarray): Likewise.
	* parse.c (operator_length_standard): Likewise.
	* rust-exp.y (rust_parser::convert_ast_to_expression): Likewise.
	* rust-lang.c (rust_range): Likewise.
	(rust_compute_range): Likewise.
	(rust_subscript): Likewise.

8 files changed, 87 insertions, 94 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 75e7ee1..427f029 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+2020-10-22  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* expprint.c (print_subexp_standard): Update to reflect changes to
+	enum range_type.
+	(dump_subexp_body_standard): Likewise.
+	* expression.h (enum range_type): Convert to a bit field enum, and
+	make the enum unsigned.
+	* f-exp.y (subrange): Update to reflect changes to enum
+	range_type.
+	* f-lang.c (value_f90_subarray): Likewise.
+	* parse.c (operator_length_standard): Likewise.
+	* rust-exp.y (rust_parser::convert_ast_to_expression): Likewise.
+	* rust-lang.c (rust_range): Likewise.
+	(rust_compute_range): Likewise.
+	(rust_subscript): Likewise.
+
 2020-10-21  Simon Marchi  <simon.marchi@efficios.com>
 
 	* infrun.c (displaced_step_in_progress_thread): Fix comment.
diff --git a/gdb/expprint.c b/gdb/expprint.c
index d7d7c87..bdb69a9 100644
--- a/gdb/expprint.c
+++ b/gdb/expprint.c
@@ -585,17 +585,13 @@ print_subexp_standard (struct expression *exp, int *pos,
 	  longest_to_int (exp->elts[pc + 1].longconst);
 	*pos += 2;
 
-	if (range_type == NONE_BOUND_DEFAULT_EXCLUSIVE
-	    || range_type == LOW_BOUND_DEFAULT_EXCLUSIVE)
+	if (range_type & RANGE_HIGH_BOUND_EXCLUSIVE)
 	  fputs_filtered ("EXCLUSIVE_", stream);
 	fputs_filtered ("RANGE(", stream);
-	if (range_type == HIGH_BOUND_DEFAULT
-	    || range_type == NONE_BOUND_DEFAULT
-	    || range_type == NONE_BOUND_DEFAULT_EXCLUSIVE)
+	if (!(range_type & RANGE_LOW_BOUND_DEFAULT))
 	  print_subexp (exp, pos, stream, PREC_ABOVE_COMMA);
 	fputs_filtered ("..", stream);
-	if (range_type == LOW_BOUND_DEFAULT
-	    || range_type == NONE_BOUND_DEFAULT)
+	if (!(range_type & RANGE_HIGH_BOUND_DEFAULT))
 	  print_subexp (exp, pos, stream, PREC_ABOVE_COMMA);
 	fputs_filtered (")", stream);
 	return;
@@ -1116,36 +1112,19 @@ dump_subexp_body_standard (struct expression *exp,
 	  longest_to_int (exp->elts[elt].longconst);
 	elt += 2;
 
-	switch (range_type)
-	  {
-	  case BOTH_BOUND_DEFAULT:
-	    fputs_filtered ("Range '..'", stream);
-	    break;
-	  case LOW_BOUND_DEFAULT:
-	    fputs_filtered ("Range '..EXP'", stream);
-	    break;
-	  case LOW_BOUND_DEFAULT_EXCLUSIVE:
-	    fputs_filtered ("ExclusiveRange '..EXP'", stream);
-	    break;
-	  case HIGH_BOUND_DEFAULT:
-	    fputs_filtered ("Range 'EXP..'", stream);
-	    break;
-	  case NONE_BOUND_DEFAULT:
-	    fputs_filtered ("Range 'EXP..EXP'", stream);
-	    break;
-	  case NONE_BOUND_DEFAULT_EXCLUSIVE:
-	    fputs_filtered ("ExclusiveRange 'EXP..EXP'", stream);
-	    break;
-	  default:
-	    fputs_filtered ("Invalid Range!", stream);
-	    break;
-	  }
+	if (range_type & RANGE_HIGH_BOUND_EXCLUSIVE)
+	  fputs_filtered ("Exclusive", stream);
+	fputs_filtered ("Range '", stream);
+	if (!(range_type & RANGE_LOW_BOUND_DEFAULT))
+	  fputs_filtered ("EXP", stream);
+	fputs_filtered ("..", stream);
+	if (!(range_type & RANGE_HIGH_BOUND_DEFAULT))
+	  fputs_filtered ("EXP", stream);
+	fputs_filtered ("'", stream);
 
-	if (range_type == HIGH_BOUND_DEFAULT
-	    || range_type == NONE_BOUND_DEFAULT)
+	if (!(range_type & RANGE_LOW_BOUND_DEFAULT))
 	  elt = dump_subexp (exp, stream, elt);
-	if (range_type == LOW_BOUND_DEFAULT
-	    || range_type == NONE_BOUND_DEFAULT)
+	if (!(range_type & RANGE_HIGH_BOUND_DEFAULT))
 	  elt = dump_subexp (exp, stream, elt);
       }
       break;
diff --git a/gdb/expression.h b/gdb/expression.h
index 5af10f0..6bd3fc0 100644
--- a/gdb/expression.h
+++ b/gdb/expression.h
@@ -185,22 +185,22 @@ extern void dump_prefix_expression (struct expression *, struct ui_file *);
    or inclusive.  So we have six sorts of subrange.  This enumeration
    type is to identify this.  */
 
-enum range_type
+enum range_type : unsigned
 {
-  /* Neither the low nor the high bound was given -- so this refers to
-     the entire available range.  */
-  BOTH_BOUND_DEFAULT,
-  /* The low bound was not given and the high bound is inclusive.  */
-  LOW_BOUND_DEFAULT,
-  /* The high bound was not given and the low bound in inclusive.  */
-  HIGH_BOUND_DEFAULT,
-  /* Both bounds were given and both are inclusive.  */
-  NONE_BOUND_DEFAULT,
-  /* The low bound was not given and the high bound is exclusive.  */
-  NONE_BOUND_DEFAULT_EXCLUSIVE,
-  /* Both bounds were given.  The low bound is inclusive and the high
-     bound is exclusive.  */
-  LOW_BOUND_DEFAULT_EXCLUSIVE,
+  /* This is a standard range.  Both the lower and upper bounds are
+     defined, and the bounds are inclusive.  */
+  RANGE_STANDARD = 0,
+
+  /* The low bound was not given.  */
+  RANGE_LOW_BOUND_DEFAULT = 1 << 0,
+
+  /* The high bound was not given.  */
+  RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
+
+  /* The high bound of this range is exclusive.  */
+  RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
 };
 
+DEF_ENUM_FLAGS_TYPE (enum range_type, range_types);
+
 #endif /* !defined (EXPRESSION_H) */
diff --git a/gdb/f-exp.y b/gdb/f-exp.y
index 0ccb3c6..a331408 100644
--- a/gdb/f-exp.y
+++ b/gdb/f-exp.y
@@ -287,26 +287,30 @@ arglist	:	arglist ',' exp   %prec ABOVE_COMMA
 /* There are four sorts of subrange types in F90.  */
 
 subrange:	exp ':' exp	%prec ABOVE_COMMA
-			{ write_exp_elt_opcode (pstate, OP_RANGE); 
-			  write_exp_elt_longcst (pstate, NONE_BOUND_DEFAULT);
+			{ write_exp_elt_opcode (pstate, OP_RANGE);
+			  write_exp_elt_longcst (pstate, RANGE_STANDARD);
 			  write_exp_elt_opcode (pstate, OP_RANGE); }
 	;
 
 subrange:	exp ':'	%prec ABOVE_COMMA
 			{ write_exp_elt_opcode (pstate, OP_RANGE);
-			  write_exp_elt_longcst (pstate, HIGH_BOUND_DEFAULT);
+			  write_exp_elt_longcst (pstate,
+						 RANGE_HIGH_BOUND_DEFAULT);
 			  write_exp_elt_opcode (pstate, OP_RANGE); }
 	;
 
 subrange:	':' exp	%prec ABOVE_COMMA
 			{ write_exp_elt_opcode (pstate, OP_RANGE);
-			  write_exp_elt_longcst (pstate, LOW_BOUND_DEFAULT);
+			  write_exp_elt_longcst (pstate,
+						 RANGE_LOW_BOUND_DEFAULT);
 			  write_exp_elt_opcode (pstate, OP_RANGE); }
 	;
 
 subrange:	':'	%prec ABOVE_COMMA
 			{ write_exp_elt_opcode (pstate, OP_RANGE);
-			  write_exp_elt_longcst (pstate, BOTH_BOUND_DEFAULT);
+			  write_exp_elt_longcst (pstate,
+						 (RANGE_LOW_BOUND_DEFAULT
+						  | RANGE_HIGH_BOUND_DEFAULT));
 			  write_exp_elt_opcode (pstate, OP_RANGE); }
 	;
 
diff --git a/gdb/f-lang.c b/gdb/f-lang.c
index e13097b..fcab973 100644
--- a/gdb/f-lang.c
+++ b/gdb/f-lang.c
@@ -131,12 +131,12 @@ value_f90_subarray (struct value *array,
 
   *pos += 3;
 
-  if (range_type == LOW_BOUND_DEFAULT || range_type == BOTH_BOUND_DEFAULT)
+  if (range_type & RANGE_LOW_BOUND_DEFAULT)
     low_bound = range->bounds ()->low.const_val ();
   else
     low_bound = value_as_long (evaluate_subexp (nullptr, exp, pos, noside));
 
-  if (range_type == HIGH_BOUND_DEFAULT || range_type == BOTH_BOUND_DEFAULT)
+  if (range_type & RANGE_HIGH_BOUND_DEFAULT)
     high_bound = range->bounds ()->high.const_val ();
   else
     high_bound = value_as_long (evaluate_subexp (nullptr, exp, pos, noside));
diff --git a/gdb/parse.c b/gdb/parse.c
index 6b9541b..6661fba 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -921,21 +921,13 @@ operator_length_standard (const struct expression *expr, int endpos,
       range_type = (enum range_type)
 	longest_to_int (expr->elts[endpos - 2].longconst);
 
-      switch (range_type)
-	{
-	case LOW_BOUND_DEFAULT:
-	case LOW_BOUND_DEFAULT_EXCLUSIVE:
-	case HIGH_BOUND_DEFAULT:
-	  args = 1;
-	  break;
-	case BOTH_BOUND_DEFAULT:
-	  args = 0;
-	  break;
-	case NONE_BOUND_DEFAULT:
-	case NONE_BOUND_DEFAULT_EXCLUSIVE:
-	  args = 2;
-	  break;
-	}
+      /* Assume the range has 2 arguments (low bound and high bound), then
+	 reduce the argument count if any bounds are set to default.  */
+      args = 2;
+      if (range_type & RANGE_LOW_BOUND_DEFAULT)
+	--args;
+      if (range_type & RANGE_HIGH_BOUND_DEFAULT)
+	--args;
 
       break;
 
diff --git a/gdb/rust-exp.y b/gdb/rust-exp.y
index db88809..ea9fbdc 100644
--- a/gdb/rust-exp.y
+++ b/gdb/rust-exp.y
@@ -2492,24 +2492,29 @@ rust_parser::convert_ast_to_expression (const struct rust_op *operation,
 
     case OP_RANGE:
       {
-	enum range_type kind = BOTH_BOUND_DEFAULT;
+	enum range_type kind = (RANGE_HIGH_BOUND_DEFAULT
+				| RANGE_LOW_BOUND_DEFAULT);
 
 	if (operation->left.op != NULL)
 	  {
 	    convert_ast_to_expression (operation->left.op, top);
-	    kind = HIGH_BOUND_DEFAULT;
+	    kind &= ~RANGE_LOW_BOUND_DEFAULT;
 	  }
 	if (operation->right.op != NULL)
 	  {
 	    convert_ast_to_expression (operation->right.op, top);
-	    if (kind == BOTH_BOUND_DEFAULT)
-	      kind = (operation->inclusive
-		      ? LOW_BOUND_DEFAULT : LOW_BOUND_DEFAULT_EXCLUSIVE);
+	    if (kind == (RANGE_HIGH_BOUND_DEFAULT | RANGE_LOW_BOUND_DEFAULT))
+	      {
+		kind = RANGE_LOW_BOUND_DEFAULT;
+		if (!operation->inclusive)
+		  kind |= RANGE_HIGH_BOUND_EXCLUSIVE;
+	      }
 	    else
 	      {
-		gdb_assert (kind == HIGH_BOUND_DEFAULT);
-		kind = (operation->inclusive
-			? NONE_BOUND_DEFAULT : NONE_BOUND_DEFAULT_EXCLUSIVE);
+		gdb_assert (kind == RANGE_HIGH_BOUND_DEFAULT);
+		kind = RANGE_STANDARD;
+		if (!operation->inclusive)
+		  kind |= RANGE_HIGH_BOUND_EXCLUSIVE;
 	      }
 	  }
 	else
diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index f7c762e..820ebb9 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -1077,13 +1077,11 @@ rust_range (struct expression *exp, int *pos, enum noside noside)
   kind = (enum range_type) longest_to_int (exp->elts[*pos + 1].longconst);
   *pos += 3;
 
-  if (kind == HIGH_BOUND_DEFAULT || kind == NONE_BOUND_DEFAULT
-      || kind == NONE_BOUND_DEFAULT_EXCLUSIVE)
+  if (!(kind & RANGE_LOW_BOUND_DEFAULT))
     low = evaluate_subexp (nullptr, exp, pos, noside);
-  if (kind == LOW_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT_EXCLUSIVE
-      || kind == NONE_BOUND_DEFAULT || kind == NONE_BOUND_DEFAULT_EXCLUSIVE)
+  if (!(kind & RANGE_HIGH_BOUND_DEFAULT))
     high = evaluate_subexp (nullptr, exp, pos, noside);
-  bool inclusive = (kind == NONE_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT);
+  bool inclusive = !(kind & RANGE_HIGH_BOUND_EXCLUSIVE);
 
   if (noside == EVAL_SKIP)
     return value_from_longest (builtin_type (exp->gdbarch)->builtin_int, 1);
@@ -1166,13 +1164,13 @@ rust_range (struct expression *exp, int *pos, enum noside noside)
 static void
 rust_compute_range (struct type *type, struct value *range,
 		    LONGEST *low, LONGEST *high,
-		    enum range_type *kind)
+		    range_types *kind)
 {
   int i;
 
   *low = 0;
   *high = 0;
-  *kind = BOTH_BOUND_DEFAULT;
+  *kind = RANGE_LOW_BOUND_DEFAULT | RANGE_HIGH_BOUND_DEFAULT;
 
   if (type->num_fields () == 0)
     return;
@@ -1180,15 +1178,15 @@ rust_compute_range (struct type *type, struct value *range,
   i = 0;
   if (strcmp (TYPE_FIELD_NAME (type, 0), "start") == 0)
     {
-      *kind = HIGH_BOUND_DEFAULT;
+      *kind = RANGE_HIGH_BOUND_DEFAULT;
       *low = value_as_long (value_field (range, 0));
       ++i;
     }
   if (type->num_fields () > i
       && strcmp (TYPE_FIELD_NAME (type, i), "end") == 0)
     {
-      *kind = (*kind == BOTH_BOUND_DEFAULT
-	       ? LOW_BOUND_DEFAULT : NONE_BOUND_DEFAULT);
+      *kind = (*kind == (RANGE_LOW_BOUND_DEFAULT | RANGE_HIGH_BOUND_DEFAULT)
+	       ? RANGE_LOW_BOUND_DEFAULT : RANGE_STANDARD);
       *high = value_as_long (value_field (range, i));
 
       if (rust_inclusive_range_type_p (type))
@@ -1206,7 +1204,7 @@ rust_subscript (struct expression *exp, int *pos, enum noside noside,
   struct type *rhstype;
   LONGEST low, high_bound;
   /* Initialized to appease the compiler.  */
-  enum range_type kind = BOTH_BOUND_DEFAULT;
+  range_types kind = RANGE_LOW_BOUND_DEFAULT | RANGE_HIGH_BOUND_DEFAULT;
   LONGEST high = 0;
   int want_slice = 0;
 
@@ -1303,8 +1301,7 @@ rust_subscript (struct expression *exp, int *pos, enum noside noside,
       else
 	error (_("Cannot subscript non-array type"));
 
-      if (want_slice
-	  && (kind == BOTH_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT))
+      if (want_slice && (kind & RANGE_LOW_BOUND_DEFAULT))
 	low = low_bound;
       if (low < 0)
 	error (_("Index less than zero"));
@@ -1322,7 +1319,7 @@ rust_subscript (struct expression *exp, int *pos, enum noside noside,
 	  CORE_ADDR addr;
 	  struct value *addrval, *tem;
 
-	  if (kind == BOTH_BOUND_DEFAULT || kind == HIGH_BOUND_DEFAULT)
+	  if (kind & RANGE_HIGH_BOUND_DEFAULT)
 	    high = high_bound;
 	  if (high < 0)
 	    error (_("High index less than zero"));