C++-ify parser_state

This mildly C++-ifies parser_state and stap_parse_info -- just enough
to remove some cleanups.

This version includes the changes implemented by Simon.

Regression tested by the buildbot.

gdb/ChangeLog
2017-12-30  Tom Tromey  <tom@tromey.com>
	    Simon Marchi  <simon.marchi@ericsson.com>

	* stap-probe.h (struct stap_parse_info): Add constructor,
	destructor.
	* stap-probe.c (stap_parse_argument): Update.
	* rust-exp.y (rust_lex_tests): Update.
	* parser-defs.h (struct parser_state): Add constructor,
	destructor, release method.
	<expout>: Change type to expression_up.
	(null_post_parser): Change type.
	(initialize_expout, reallocate_expout): Remove.
	* parse.c (parser_state::parser_state): Rename from
	initialize_expout.
	(parser_state::release): Rename from reallocate_expout.
	(write_exp_elt, parse_exp_in_context_1, increase_expout_size):
	Update.
	(null_post_parser): Change type of "exp".
	* dtrace-probe.c (dtrace_probe::build_arg_exprs): Update.
	* ada-lang.c (resolve, resolve_subexp)
	(replace_operator_with_call): Change type of "expp".
	* language.h (struct language_defn) <la_post_parser>: Change type
	of "expp".

gdb/parse.c

@@ -152,34 +152,32 @@ end_arglist (void)
 
 /* See definition in parser-defs.h.  */
 
-void
-initialize_expout (struct parser_state *ps, size_t initial_size,
-		   const struct language_defn *lang,
-		   struct gdbarch *gdbarch)
+parser_state::parser_state (size_t initial_size,
+			    const struct language_defn *lang,
+			    struct gdbarch *gdbarch)
+  : expout_size (initial_size),
+    expout (XNEWVAR (expression,
+		     (sizeof (expression)
+		      + EXP_ELEM_TO_BYTES (expout_size)))),
+    expout_ptr (0)
 {
-  ps->expout_size = initial_size;
-  ps->expout_ptr = 0;
-  ps->expout
-    = (struct expression *) xmalloc (sizeof (struct expression)
-				     + EXP_ELEM_TO_BYTES (ps->expout_size));
-  ps->expout->language_defn = lang;
-  ps->expout->gdbarch = gdbarch;
+  expout->language_defn = lang;
+  expout->gdbarch = gdbarch;
 }
 
-/* See definition in parser-defs.h.  */
-
-void
-reallocate_expout (struct parser_state *ps)
+expression_up
+parser_state::release ()
 {
   /* Record the actual number of expression elements, and then
      reallocate the expression memory so that we free up any
      excess elements.  */
 
-  ps->expout->nelts = ps->expout_ptr;
-  ps->expout = (struct expression *)
-     xrealloc (ps->expout,
-	       sizeof (struct expression)
-	       + EXP_ELEM_TO_BYTES (ps->expout_ptr));
+  expout->nelts = expout_ptr;
+  expout.reset (XRESIZEVAR (expression, expout.release (),
+			    (sizeof (expression)
+			     + EXP_ELEM_TO_BYTES (expout_ptr))));
+
+  return std::move (expout);
 }
 
 /* This page contains the functions for adding data to the struct expression
@@ -196,9 +194,9 @@ write_exp_elt (struct parser_state *ps, const union exp_element *expelt)
   if (ps->expout_ptr >= ps->expout_size)
     {
       ps->expout_size *= 2;
-      ps->expout = (struct expression *)
-	xrealloc (ps->expout, sizeof (struct expression)
-		  + EXP_ELEM_TO_BYTES (ps->expout_size));
+      ps->expout.reset (XRESIZEVAR (expression, ps->expout.release (),
+				    (sizeof (expression)
+				     + EXP_ELEM_TO_BYTES (ps->expout_size))));
     }
   ps->expout->elts[ps->expout_ptr++] = *expelt;
 }
@@ -1116,7 +1114,6 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
 			int comma, int void_context_p, int *out_subexp)
 {
   const struct language_defn *lang = NULL;
-  struct parser_state ps;
   int subexp;
 
   lexptr = *stringptr;
@@ -1192,7 +1189,7 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
      and others called from *.y) ensure CURRENT_LANGUAGE gets restored
      to the value matching SELECTED_FRAME as set by get_current_arch.  */
 
-  initialize_expout (&ps, 10, lang, get_current_arch ());
+  parser_state ps (10, lang, get_current_arch ());
 
   scoped_restore_current_language lang_saver;
   set_language (lang->la_language);
@@ -1205,33 +1202,32 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
   CATCH (except, RETURN_MASK_ALL)
     {
       if (! parse_completion)
-	{
-	  xfree (ps.expout);
-	  throw_exception (except);
-	}
+	throw_exception (except);
     }
   END_CATCH
 
-  reallocate_expout (&ps);
+  /* We have to operate on an "expression *", due to la_post_parser,
+     which explains this funny-looking double release.  */
+  expression_up result = ps.release ();
 
   /* Convert expression from postfix form as generated by yacc
      parser, to a prefix form.  */
 
   if (expressiondebug)
-    dump_raw_expression (ps.expout, gdb_stdlog,
+    dump_raw_expression (result.get (), gdb_stdlog,
 			 "before conversion to prefix form");
 
-  subexp = prefixify_expression (ps.expout);
+  subexp = prefixify_expression (result.get ());
   if (out_subexp)
     *out_subexp = subexp;
 
-  lang->la_post_parser (&ps.expout, void_context_p);
+  lang->la_post_parser (&result, void_context_p);
 
   if (expressiondebug)
-    dump_prefix_expression (ps.expout, gdb_stdlog);
+    dump_prefix_expression (result.get (), gdb_stdlog);
 
   *stringptr = lexptr;
-  return expression_up (ps.expout);
+  return result;
 }
 
 /* Parse STRING as an expression, and complain if this fails
@@ -1320,7 +1316,7 @@ parse_expression_for_completion (const char *string, char **name,
 /* A post-parser that does nothing.  */
 
 void
-null_post_parser (struct expression **exp, int void_context_p)
+null_post_parser (expression_up *exp, int void_context_p)
 {
 }
 
@@ -1866,10 +1862,11 @@ increase_expout_size (struct parser_state *ps, size_t lenelt)
   if ((ps->expout_ptr + lenelt) >= ps->expout_size)
     {
       ps->expout_size = std::max (ps->expout_size * 2,
-			     ps->expout_ptr + lenelt + 10);
-      ps->expout = (struct expression *)
-	xrealloc (ps->expout, (sizeof (struct expression)
-			       + EXP_ELEM_TO_BYTES (ps->expout_size)));
+				  ps->expout_ptr + lenelt + 10);
+      ps->expout.reset (XRESIZEVAR (expression,
+				    ps->expout.release (),
+				    (sizeof (struct expression)
+				     + EXP_ELEM_TO_BYTES (ps->expout_size))));
     }
 }