[PATCH 185/203] Remove now-unused Rust evaluator code

[Tom Tromey <tom@tromey.com>]

Now that the Rust parser has switched to the new style, there is no
need for the old Rust evaluation code.

gdb/ChangeLog
2021-01-01  Tom Tromey  <tom@tromey.com>

	* rust-lang.h (class rust_language) <expression_ops,
	exp_descriptor_tab>: Remove.
	* rust-lang.c (rust_evaluate_funcall): Remove.
	(rust_range, rust_subscript, eval_op_rust_complement): Don't use
	EVAL_SKIP.
	(rust_evaluate_subexp): Remove.
	(rust_aggregate_operation::evaluate): Don't use EVAL_SKIP.
	(rust_operator_length, rust_dump_subexp_body, rust_print_subexp)
	(rust_operator_check, rust_language::exp_descriptor_tab): Remove.
---
 gdb/ChangeLog   |  12 ++
 gdb/rust-lang.c | 507 +-----------------------------------------------
 gdb/rust-lang.h |  10 -
 3 files changed, 13 insertions(+), 516 deletions(-)

diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index 7605b64b384..5a4a4bb9937 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -963,82 +963,6 @@ rust_slice_type (const char *name, struct type *elt_type,
 
 \f
 
-/* A helper for rust_evaluate_subexp that handles OP_FUNCALL.  */
-
-static struct value *
-rust_evaluate_funcall (struct expression *exp, int *pos, enum noside noside)
-{
-  int i;
-  int num_args = exp->elts[*pos + 1].longconst;
-  const char *method;
-  struct value *function, *result, *arg0;
-  struct type *type, *fn_type;
-  const struct block *block;
-  struct block_symbol sym;
-
-  /* For an ordinary function call we can simply defer to the
-     generic implementation.  */
-  if (exp->elts[*pos + 3].opcode != STRUCTOP_STRUCT)
-    return evaluate_subexp_standard (NULL, exp, pos, noside);
-
-  /* Skip over the OP_FUNCALL and the STRUCTOP_STRUCT.  */
-  *pos += 4;
-  method = &exp->elts[*pos + 1].string;
-  *pos += 3 + BYTES_TO_EXP_ELEM (exp->elts[*pos].longconst + 1);
-
-  /* Evaluate the argument to STRUCTOP_STRUCT, then find its
-     type in order to look up the method.  */
-  arg0 = evaluate_subexp (nullptr, exp, pos, noside);
-
-  if (noside == EVAL_SKIP)
-    {
-      for (i = 0; i < num_args; ++i)
-	evaluate_subexp (nullptr, exp, pos, noside);
-      return arg0;
-    }
-
-  std::vector<struct value *> args (num_args + 1);
-  args[0] = arg0;
-
-  /* We don't yet implement real Deref semantics.  */
-  while (value_type (args[0])->code () == TYPE_CODE_PTR)
-    args[0] = value_ind (args[0]);
-
-  type = value_type (args[0]);
-  if ((type->code () != TYPE_CODE_STRUCT
-       && type->code () != TYPE_CODE_UNION
-       && type->code () != TYPE_CODE_ENUM)
-      || rust_tuple_type_p (type))
-    error (_("Method calls only supported on struct or enum types"));
-  if (type->name () == NULL)
-    error (_("Method call on nameless type"));
-
-  std::string name = std::string (type->name ()) + "::" + method;
-
-  block = get_selected_block (0);
-  sym = lookup_symbol (name.c_str (), block, VAR_DOMAIN, NULL);
-  if (sym.symbol == NULL)
-    error (_("Could not find function named '%s'"), name.c_str ());
-
-  fn_type = SYMBOL_TYPE (sym.symbol);
-  if (fn_type->num_fields () == 0)
-    error (_("Function '%s' takes no arguments"), name.c_str ());
-
-  if (fn_type->field (0).type ()->code () == TYPE_CODE_PTR)
-    args[0] = value_addr (args[0]);
-
-  function = address_of_variable (sym.symbol, block);
-
-  for (i = 0; i < num_args; ++i)
-    args[i + 1] = evaluate_subexp (nullptr, exp, pos, noside);
-
-  if (noside == EVAL_AVOID_SIDE_EFFECTS)
-    result = value_zero (TYPE_TARGET_TYPE (fn_type), not_lval);
-  else
-    result = call_function_by_hand (function, NULL, args);
-  return result;
-}
-
 /* A helper for rust_evaluate_subexp that handles OP_RANGE.  */
 
 struct value *
@@ -1055,9 +979,6 @@ rust_range (struct type *expect_type, struct expression *exp,
 
   bool inclusive = !(kind & RANGE_HIGH_BOUND_EXCLUSIVE);
 
-  if (noside == EVAL_SKIP)
-    return value_from_longest (builtin_type (exp->gdbarch)->builtin_int, 1);
-
   if (low == NULL)
     {
       if (high == NULL)
@@ -1181,9 +1102,6 @@ rust_subscript (struct type *expect_type, struct expression *exp,
   LONGEST high = 0;
   int want_slice = 0;
 
-  if (noside == EVAL_SKIP)
-    return lhs;
-
   rhstype = check_typedef (value_type (rhs));
   if (rust_range_type_p (rhstype))
     {
@@ -1347,11 +1265,6 @@ eval_op_rust_complement (struct type *expect_type, struct expression *exp,
 			 enum exp_opcode opcode,
 			 struct value *value)
 {
-  if (noside == EVAL_SKIP)
-    {
-      /* Preserving the type is enough.  */
-      return value;
-    }
   if (value_type (value)->code () == TYPE_CODE_BOOL)
     return value_from_longest (value_type (value), value_logical_not (value));
   return value_complement (value);
@@ -1502,204 +1415,6 @@ eval_op_rust_structop (struct type *expect_type, struct expression *exp,
   return result;
 }
 
-/* evaluate_exp implementation for Rust.  */
-
-static struct value *
-rust_evaluate_subexp (struct type *expect_type, struct expression *exp,
-		      int *pos, enum noside noside)
-{
-  struct value *result;
-  enum exp_opcode op = exp->elts[*pos].opcode;
-
-  switch (op)
-    {
-    case UNOP_IND:
-      {
-	if (noside != EVAL_NORMAL)
-	  result = evaluate_subexp_standard (expect_type, exp, pos, noside);
-	else
-	  {
-	    ++*pos;
-	    struct value *value = evaluate_subexp (expect_type, exp, pos,
-						   noside);
-	    result = eval_op_rust_ind (expect_type, exp, noside, op, value);
-	  }
-      }
-      break;
-
-    case UNOP_COMPLEMENT:
-      {
-	struct value *value;
-
-	++*pos;
-	value = evaluate_subexp (nullptr, exp, pos, noside);
-	result = eval_op_rust_complement (expect_type, exp, noside, op, value);
-      }
-      break;
-
-    case BINOP_SUBSCRIPT:
-      {
-	++*pos;
-	struct value *lhs = evaluate_subexp (nullptr, exp, pos, noside);
-	struct value *rhs = evaluate_subexp (nullptr, exp, pos, noside);
-	result = rust_subscript (expect_type, exp, noside, false, lhs, rhs);
-      }
-      break;
-
-    case OP_FUNCALL:
-      result = rust_evaluate_funcall (exp, pos, noside);
-      break;
-
-    case OP_AGGREGATE:
-      {
-	int pc = (*pos)++;
-	struct type *type = exp->elts[pc + 1].type;
-	int arglen = longest_to_int (exp->elts[pc + 2].longconst);
-	int i;
-	CORE_ADDR addr = 0;
-	struct value *addrval = NULL;
-
-	*pos += 3;
-
-	if (noside == EVAL_NORMAL)
-	  {
-	    addrval = value_allocate_space_in_inferior (TYPE_LENGTH (type));
-	    addr = value_as_long (addrval);
-	    result = value_at_lazy (type, addr);
-	  }
-
-	if (arglen > 0 && exp->elts[*pos].opcode == OP_OTHERS)
-	  {
-	    struct value *init;
-
-	    ++*pos;
-	    init = rust_evaluate_subexp (NULL, exp, pos, noside);
-	    if (noside == EVAL_NORMAL)
-	      {
-		/* This isn't quite right but will do for the time
-		   being, seeing that we can't implement the Copy
-		   trait anyway.  */
-		value_assign (result, init);
-	      }
-
-	    --arglen;
-	  }
-
-	gdb_assert (arglen % 2 == 0);
-	for (i = 0; i < arglen; i += 2)
-	  {
-	    int len;
-	    const char *fieldname;
-	    struct value *value, *field;
-
-	    gdb_assert (exp->elts[*pos].opcode == OP_NAME);
-	    ++*pos;
-	    len = longest_to_int (exp->elts[*pos].longconst);
-	    ++*pos;
-	    fieldname = &exp->elts[*pos].string;
-	    *pos += 2 + BYTES_TO_EXP_ELEM (len + 1);
-
-	    value = rust_evaluate_subexp (NULL, exp, pos, noside);
-	    if (noside == EVAL_NORMAL)
-	      {
-		field = value_struct_elt (&result, NULL, fieldname, NULL,
-					  "structure");
-		value_assign (field, value);
-	      }
-	  }
-
-	if (noside == EVAL_SKIP)
-	  return value_from_longest (builtin_type (exp->gdbarch)->builtin_int,
-				     1);
-	else if (noside == EVAL_AVOID_SIDE_EFFECTS)
-	  result = allocate_value (type);
-	else
-	  result = value_at_lazy (type, addr);
-      }
-      break;
-
-    case OP_RUST_ARRAY:
-      {
-	(*pos)++;
-	struct value *elt;
-	struct value *ncopies;
-
-	elt = rust_evaluate_subexp (NULL, exp, pos, noside);
-	ncopies = rust_evaluate_subexp (NULL, exp, pos, noside);
-	return eval_op_rust_array (expect_type, exp, noside, op, elt, ncopies);
-      }
-      break;
-
-    case STRUCTOP_ANONYMOUS:
-      {
-	/* Anonymous field access, i.e. foo.1.  */
-	struct value *lhs;
-	int pc, field_number;
-
-	pc = (*pos)++;
-	field_number = longest_to_int (exp->elts[pc + 1].longconst);
-	(*pos) += 2;
-	lhs = evaluate_subexp (nullptr, exp, pos, noside);
-
-	return eval_op_rust_struct_anon (expect_type, exp, noside,
-					 field_number, lhs);
-      }
-      break;
-
-    case STRUCTOP_STRUCT:
-      {
-	struct value *lhs;
-	int tem, pc;
-
-	pc = (*pos)++;
-	tem = longest_to_int (exp->elts[pc + 1].longconst);
-	(*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
-	lhs = evaluate_subexp (nullptr, exp, pos, noside);
-
-	const char *field_name = &exp->elts[pc + 2].string;
-	return eval_op_rust_structop (expect_type, exp, noside, lhs,
-				      field_name);
-      }
-      break;
-
-    case OP_RANGE:
-      {
-	struct value *low = NULL, *high = NULL;
-	auto kind
-	  = (enum range_flag) longest_to_int (exp->elts[*pos + 1].longconst);
-	*pos += 3;
-
-	if (!(kind & RANGE_LOW_BOUND_DEFAULT))
-	  low = evaluate_subexp (nullptr, exp, pos, noside);
-	if (!(kind & RANGE_HIGH_BOUND_DEFAULT))
-	  high = evaluate_subexp (nullptr, exp, pos, noside);
-
-	result = rust_range (expect_type, exp, noside, kind, low, high);
-      }
-      break;
-
-    case UNOP_ADDR:
-      /* We might have &array[range], in which case we need to make a
-	 slice.  */
-      if (exp->elts[*pos + 1].opcode == BINOP_SUBSCRIPT)
-	{
-	  ++*pos;
-	  ++*pos;
-	  struct value *lhs = evaluate_subexp (nullptr, exp, pos, noside);
-	  struct value *rhs = evaluate_subexp (nullptr, exp, pos, noside);
-
-	  result = rust_subscript (expect_type, exp, noside, true, lhs, rhs);
-	  break;
-	}
-      /* Fall through.  */
-    default:
-      result = evaluate_subexp_standard (expect_type, exp, pos, noside);
-      break;
-    }
-
-  return result;
-}
-
 namespace expr
 {
 
@@ -1746,9 +1461,7 @@ rust_aggregate_operation::evaluate (struct type *expect_type,
 	}
     }
 
-  if (noside == EVAL_SKIP)
-    result = value_from_longest (builtin_type (exp->gdbarch)->builtin_int, 1);
-  else if (noside == EVAL_AVOID_SIDE_EFFECTS)
+  if (noside == EVAL_AVOID_SIDE_EFFECTS)
     result = allocate_value (type);
   else
     result = value_at_lazy (type, addr);
@@ -1808,226 +1521,8 @@ rust_structop::evaluate_funcall (struct type *expect_type,
 
 }
 
-/* operator_length implementation for Rust.  */
-
-static void
-rust_operator_length (const struct expression *exp, int pc, int *oplenp,
-		      int *argsp)
-{
-  int oplen = 1;
-  int args = 0;
-
-  switch (exp->elts[pc - 1].opcode)
-    {
-    case OP_AGGREGATE:
-      /* We handle aggregate as a type and argument count.  The first
-	 argument might be OP_OTHERS.  After that the arguments
-	 alternate: first an OP_NAME, then an expression.  */
-      oplen = 4;
-      args = longest_to_int (exp->elts[pc - 2].longconst);
-      break;
-
-    case OP_OTHERS:
-      oplen = 1;
-      args = 1;
-      break;
-
-    case STRUCTOP_ANONYMOUS:
-      oplen = 3;
-      args = 1;
-      break;
-
-    case OP_RUST_ARRAY:
-      oplen = 1;
-      args = 2;
-      break;
-
-    default:
-      operator_length_standard (exp, pc, oplenp, argsp);
-      return;
-    }
-
-  *oplenp = oplen;
-  *argsp = args;
-}
-
-/* dump_subexp_body implementation for Rust.  */
-
-static int
-rust_dump_subexp_body (struct expression *exp, struct ui_file *stream,
-		       int elt)
-{
-  switch (exp->elts[elt].opcode)
-    {
-    case OP_AGGREGATE:
-      {
-	int length = longest_to_int (exp->elts[elt + 2].longconst);
-	int i;
-
-	fprintf_filtered (stream, "Type @");
-	gdb_print_host_address (exp->elts[elt + 1].type, stream);
-	fprintf_filtered (stream, " (");
-	type_print (exp->elts[elt + 1].type, NULL, stream, 0);
-	fprintf_filtered (stream, "), length %d", length);
-
-	elt += 4;
-	for (i = 0; i < length; ++i)
-	  elt = dump_subexp (exp, stream, elt);
-      }
-      break;
-
-    case OP_STRING:
-    case OP_NAME:
-      {
-	LONGEST len = exp->elts[elt + 1].longconst;
-
-	fprintf_filtered (stream, "%s: %s",
-			  (exp->elts[elt].opcode == OP_STRING
-			   ? "string" : "name"),
-			  &exp->elts[elt + 2].string);
-	elt += 4 + BYTES_TO_EXP_ELEM (len + 1);
-      }
-      break;
-
-    case OP_OTHERS:
-      elt = dump_subexp (exp, stream, elt + 1);
-      break;
-
-    case STRUCTOP_ANONYMOUS:
-      {
-	int field_number;
-
-	field_number = longest_to_int (exp->elts[elt + 1].longconst);
-
-	fprintf_filtered (stream, "Field number: %d", field_number);
-	elt = dump_subexp (exp, stream, elt + 3);
-      }
-      break;
-
-    case OP_RUST_ARRAY:
-      ++elt;
-      break;
-
-    default:
-      elt = dump_subexp_body_standard (exp, stream, elt);
-      break;
-    }
-
-  return elt;
-}
-
-/* print_subexp implementation for Rust.  */
-
-static void
-rust_print_subexp (struct expression *exp, int *pos, struct ui_file *stream,
-		   enum precedence prec)
-{
-  switch (exp->elts[*pos].opcode)
-    {
-    case OP_AGGREGATE:
-      {
-	int length = longest_to_int (exp->elts[*pos + 2].longconst);
-	int i;
-
-	type_print (exp->elts[*pos + 1].type, "", stream, 0);
-	fputs_filtered (" { ", stream);
-
-	*pos += 4;
-	for (i = 0; i < length; ++i)
-	  {
-	    rust_print_subexp (exp, pos, stream, prec);
-	    fputs_filtered (", ", stream);
-	  }
-	fputs_filtered (" }", stream);
-      }
-      break;
-
-    case OP_NAME:
-      {
-	LONGEST len = exp->elts[*pos + 1].longconst;
-
-	fputs_filtered (&exp->elts[*pos + 2].string, stream);
-	*pos += 4 + BYTES_TO_EXP_ELEM (len + 1);
-      }
-      break;
-
-    case OP_OTHERS:
-      {
-	fputs_filtered ("<<others>> (", stream);
-	++*pos;
-	rust_print_subexp (exp, pos, stream, prec);
-	fputs_filtered (")", stream);
-      }
-      break;
-
-    case STRUCTOP_ANONYMOUS:
-      {
-	int tem = longest_to_int (exp->elts[*pos + 1].longconst);
-
-	(*pos) += 3;
-	print_subexp (exp, pos, stream, PREC_SUFFIX);
-	fprintf_filtered (stream, ".%d", tem);
-      }
-      break;
-
-    case OP_RUST_ARRAY:
-      ++*pos;
-      fprintf_filtered (stream, "[");
-      rust_print_subexp (exp, pos, stream, prec);
-      fprintf_filtered (stream, "; ");
-      rust_print_subexp (exp, pos, stream, prec);
-      fprintf_filtered (stream, "]");
-      break;
-
-    default:
-      print_subexp_standard (exp, pos, stream, prec);
-      break;
-    }
-}
-
-/* operator_check implementation for Rust.  */
-
-static int
-rust_operator_check (struct expression *exp, int pos,
-		     int (*objfile_func) (struct objfile *objfile,
-					  void *data),
-		     void *data)
-{
-  switch (exp->elts[pos].opcode)
-    {
-    case OP_AGGREGATE:
-      {
-	struct type *type = exp->elts[pos + 1].type;
-	struct objfile *objfile = TYPE_OBJFILE (type);
-
-	if (objfile != NULL && (*objfile_func) (objfile, data))
-	  return 1;
-      }
-      break;
-
-    case OP_OTHERS:
-    case OP_NAME:
-    case OP_RUST_ARRAY:
-      break;
-
-    default:
-      return operator_check_standard (exp, pos, objfile_func, data);
-    }
-
-  return 0;
-}
-
 \f
 
-const struct exp_descriptor rust_language::exp_descriptor_tab =
-{
-  rust_print_subexp,
-  rust_operator_length,
-  rust_operator_check,
-  rust_dump_subexp_body,
-  rust_evaluate_subexp
-};
-
 /* See language.h.  */
 
 void
diff --git a/gdb/rust-lang.h b/gdb/rust-lang.h
index fb27f60eeab..ec97cac3dae 100644
--- a/gdb/rust-lang.h
+++ b/gdb/rust-lang.h
@@ -211,21 +211,11 @@ class rust_language : public language_defn
 
   /* See language.h.  */
 
-  const struct exp_descriptor *expression_ops () const override
-  { return &exp_descriptor_tab; }
-
-  /* See language.h.  */
-
   const struct op_print *opcode_print_table () const override
   { return c_op_print_tab; }
 
 private:
 
-  /* Table of expression handling functions for use by EXPRESSION_OPS
-     member function.  */
-
-  static const struct exp_descriptor exp_descriptor_tab;
-
   /* Helper for value_print_inner, arguments are as for that function.
      Prints structs and untagged unions.  */
 
-- 
2.26.2