gdb

	* value.h (evaluate_subexpression_type, extract_field_op):
	Declare.
	* printcmd.c (_initialize_printcmd): Use expression_completer for
	'p', 'inspect', 'call'.
	* parser-defs.h (parse_field_expression): Declare.
	* parse.c: Include exceptions.h.
	(in_parse_field, expout_last_struct): New globals.
	(mark_struct_expression): New function.
	(prefixify_expression): Return int.
	(prefixify_subexp): Return int.  Use expout_last_struct.
	(parse_exp_1): Update.
	(parse_exp_in_context): Add 'out_subexp' argument.  Handle
	in_parse_field.
	(parse_field_expression): New function.
	* expression.h (parse_field_expression): Declare.
	(in_parse_field): Likewise.
	* eval.c (evaluate_subexpression_type): New function.
	(extract_field_op): Likewise.
	* completer.h (expression_completer): Declare.
	* completer.c (expression_completer): New function.
	(count_struct_fields, add_struct_fields): New functions.
	* c-exp.y (yyparse): Redefine.
	(COMPLETE): New token.
	(exp): New productions.
	(saw_name_at_eof, last_was_structop): New globals.
	(yylex): Return COMPLETE when needed.  Recognize in_parse_field.
	(c_parse): New function.
	* breakpoint.c (_initialize_breakpoint): Use expression_completer
	for watch, awatch, and rwatch.
	* Makefile.in (parse.o): Depend on exceptions_h.
gdb/testsuite
	* gdb.base/break1.c (struct some_struct): New struct.
	(values): New global.
	* gdb.base/completion.exp: Add field name completion test.
gdb/doc
	* gdb.texinfo (Completion): Add field name example.

18 files changed, 451 insertions, 30 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 897ee48..29f89cf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,36 @@
+2008-06-06  Tom Tromey  <tromey@redhat.com>
+
+	* value.h (evaluate_subexpression_type, extract_field_op):
+	Declare.
+	* printcmd.c (_initialize_printcmd): Use expression_completer for
+	'p', 'inspect', 'call'.
+	* parser-defs.h (parse_field_expression): Declare.
+	* parse.c: Include exceptions.h.
+	(in_parse_field, expout_last_struct): New globals.
+	(mark_struct_expression): New function.
+	(prefixify_expression): Return int.
+	(prefixify_subexp): Return int.  Use expout_last_struct.
+	(parse_exp_1): Update.
+	(parse_exp_in_context): Add 'out_subexp' argument.  Handle
+	in_parse_field.
+	(parse_field_expression): New function.
+	* expression.h (parse_field_expression): Declare.
+	(in_parse_field): Likewise.
+	* eval.c (evaluate_subexpression_type): New function.
+	(extract_field_op): Likewise.
+	* completer.h (expression_completer): Declare.
+	* completer.c (expression_completer): New function.
+	(count_struct_fields, add_struct_fields): New functions.
+	* c-exp.y (yyparse): Redefine.
+	(COMPLETE): New token.
+	(exp): New productions.
+	(saw_name_at_eof, last_was_structop): New globals.
+	(yylex): Return COMPLETE when needed.  Recognize in_parse_field.
+	(c_parse): New function.
+	* breakpoint.c (_initialize_breakpoint): Use expression_completer
+	for watch, awatch, and rwatch.
+	* Makefile.in (parse.o): Depend on exceptions_h.
+
 2008-06-06  Paul Pluzhnikov  <ppluzhnikov@google.com>
 
 	PR gdb/1147
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 7132b48..c14dc1a 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -2591,7 +2591,8 @@ osabi.o: osabi.c $(defs_h) $(gdb_assert_h) $(gdb_string_h) $(osabi_h) \
 parse.o: parse.c $(defs_h) $(gdb_string_h) $(symtab_h) $(gdbtypes_h) \
 	$(frame_h) $(expression_h) $(value_h) $(command_h) $(language_h) \
 	$(f_lang_h) $(parser_defs_h) $(gdbcmd_h) $(symfile_h) $(inferior_h) \
-	$(doublest_h) $(gdb_assert_h) $(block_h) $(source_h) $(objfiles_h)
+	$(doublest_h) $(gdb_assert_h) $(block_h) $(source_h) $(objfiles_h) \
+	$(exceptions_h)
 p-exp.o: p-exp.c $(defs_h) $(gdb_string_h) $(expression_h) $(value_h) \
 	$(parser_defs_h) $(language_h) $(p_lang_h) $(bfd_h) $(symfile_h) \
 	$(objfiles_h) $(block_h)
diff --git a/gdb/NEWS b/gdb/NEWS
index 1a11319..523f328 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,17 @@
 
 *** Changes since GDB 6.8
 
+* When completing in expressions, gdb will attempt to limit
+completions to allowable structure or union fields, where appropriate.
+For instance, consider:
+
+    # struct example { int f1; double f2; };
+    # struct example variable;
+    (gdb) p variable.
+
+If the user types TAB at the end of this command line, the available
+completions will be "f1" and "f2".
+
 * New remote packets
 
 qSearch:memory:
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 808d062..051b753 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -8455,19 +8455,19 @@ by using \"enable delete\" on the catchpoint number."));
 Set a watchpoint for an expression.\n\
 A watchpoint stops execution of your program whenever the value of\n\
 an expression changes."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
 
   c = add_com ("rwatch", class_breakpoint, rwatch_command, _("\
 Set a read watchpoint for an expression.\n\
 A watchpoint stops execution of your program whenever the value of\n\
 an expression is read."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
 
   c = add_com ("awatch", class_breakpoint, awatch_command, _("\
 Set a watchpoint for an expression.\n\
 A watchpoint stops execution of your program whenever the value of\n\
 an expression is either read or written."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
 
   add_info ("watchpoints", breakpoints_info,
 	    _("Synonym for ``info breakpoints''."));
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index 3729633..9cf63d8 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -63,7 +63,7 @@ Boston, MA 02110-1301, USA.  */
    generators need to be fixed instead of adding those names to this list. */
 
 #define	yymaxdepth c_maxdepth
-#define	yyparse	c_parse
+#define	yyparse	c_parse_internal
 #define	yylex	c_lex
 #define	yyerror	c_error
 #define	yylval	c_lval
@@ -180,6 +180,7 @@ static int parse_number (char *, int, int, YYSTYPE *);
 
 %token <sval> STRING
 %token <ssym> NAME /* BLOCKNAME defined below to give it higher precedence. */
+%token <voidval> COMPLETE
 %token <tsym> TYPENAME
 %type <sval> name
 %type <ssym> name_not_typename
@@ -301,6 +302,23 @@ exp	:	exp ARROW name
 			  write_exp_elt_opcode (STRUCTOP_PTR); }
 	;
 
+exp	:	exp ARROW name COMPLETE
+			{ mark_struct_expression ();
+			  write_exp_elt_opcode (STRUCTOP_PTR);
+			  write_exp_string ($3);
+			  write_exp_elt_opcode (STRUCTOP_PTR); }
+	;
+
+exp	:	exp ARROW COMPLETE
+			{ struct stoken s;
+			  mark_struct_expression ();
+			  write_exp_elt_opcode (STRUCTOP_PTR);
+			  s.ptr = "";
+			  s.length = 0;
+			  write_exp_string (s);
+			  write_exp_elt_opcode (STRUCTOP_PTR); }
+	;
+
 exp	:	exp ARROW qualified_name
 			{ /* exp->type::name becomes exp->*(&type::name) */
 			  /* Note: this doesn't work if name is a
@@ -319,6 +337,23 @@ exp	:	exp '.' name
 			  write_exp_elt_opcode (STRUCTOP_STRUCT); }
 	;
 
+exp	:	exp '.' name COMPLETE
+			{ mark_struct_expression ();
+			  write_exp_elt_opcode (STRUCTOP_STRUCT);
+			  write_exp_string ($3);
+			  write_exp_elt_opcode (STRUCTOP_STRUCT); }
+	;
+
+exp	:	exp '.' COMPLETE
+			{ struct stoken s;
+			  mark_struct_expression ();
+			  write_exp_elt_opcode (STRUCTOP_STRUCT);
+			  s.ptr = "";
+			  s.length = 0;
+			  write_exp_string (s);
+			  write_exp_elt_opcode (STRUCTOP_STRUCT); }
+	;
+
 exp	:	exp '.' qualified_name
 			{ /* exp.type::name becomes exp.*(&type::name) */
 			  /* Note: this doesn't work if name is a
@@ -1338,6 +1373,16 @@ static const struct token tokentab2[] =
     {">=", GEQ, BINOP_END}
   };
 
+/* This is set if a NAME token appeared at the very end of the input
+   string, with no whitespace separating the name from the EOF.  This
+   is used only when parsing to do field name completion.  */
+static int saw_name_at_eof;
+
+/* This is set if the previously-returned token was a structure
+   operator -- either '.' or ARROW.  This is used only when parsing to
+   do field name completion.  */
+static int last_was_structop;
+
 /* Read one token, getting characters through lexptr.  */
 
 static int
@@ -1353,7 +1398,10 @@ yylex ()
   static int tempbufsize;
   char * token_string = NULL;
   int class_prefix = 0;
-   
+  int saw_structop = last_was_structop;
+
+  last_was_structop = 0;
+
  retry:
 
   /* Check if this is a macro invocation that we need to expand.  */
@@ -1385,6 +1433,8 @@ yylex ()
       {
 	lexptr += 2;
 	yylval.opcode = tokentab2[i].opcode;
+	if (in_parse_field && tokentab2[i].opcode == ARROW)
+	  last_was_structop = 1;
 	return tokentab2[i].token;
       }
 
@@ -1393,6 +1443,8 @@ yylex ()
     case 0:
       /* If we were just scanning the result of a macro expansion,
          then we need to resume scanning the original text.
+	 If we're parsing for field name completion, and the previous
+	 token allows such completion, return a COMPLETE token.
          Otherwise, we were already scanning the original text, and
          we're really done.  */
       if (scanning_macro_expansion ())
@@ -1400,6 +1452,13 @@ yylex ()
           finished_macro_expansion ();
           goto retry;
         }
+      else if (saw_name_at_eof)
+	{
+	  saw_name_at_eof = 0;
+	  return COMPLETE;
+	}
+      else if (saw_structop)
+	return COMPLETE;
       else
         return 0;
 
@@ -1472,7 +1531,11 @@ yylex ()
     case '.':
       /* Might be a floating point number.  */
       if (lexptr[1] < '0' || lexptr[1] > '9')
-	goto symbol;		/* Nope, must be a symbol. */
+	{
+	  if (in_parse_field)
+	    last_was_structop = 1;
+	  goto symbol;		/* Nope, must be a symbol. */
+	}
       /* FALL THRU into number case.  */
 
     case '0':
@@ -1808,10 +1871,20 @@ yylex ()
     /* Any other kind of symbol */
     yylval.ssym.sym = sym;
     yylval.ssym.is_a_field_of_this = is_a_field_of_this;
+    if (in_parse_field && *lexptr == '\0')
+      saw_name_at_eof = 1;
     return NAME;
   }
 }
 
+int
+c_parse (void)
+{
+  last_was_structop = 0;
+  saw_name_at_eof = 0;
+  return yyparse ();
+}
+
 void
 yyerror (msg)
      char *msg;
diff --git a/gdb/completer.c b/gdb/completer.c
index 3d3d34c..163a9dc 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -338,6 +338,90 @@ location_completer (char *text, char *word)
   return list;
 }
 
+/* Helper for expression_completer which recursively counts the number
+   of named fields in a structure or union type.  */
+static int
+count_struct_fields (struct type *type)
+{
+  int i, result = 0;
+
+  CHECK_TYPEDEF (type);
+  for (i = 0; i < TYPE_NFIELDS (type); ++i)
+    {
+      if (i < TYPE_N_BASECLASSES (type))
+	result += count_struct_fields (TYPE_BASECLASS (type, i));
+      else if (TYPE_FIELD_NAME (type, i))
+	++result;
+    }
+  return result;
+}
+
+/* Helper for expression_completer which recursively adds field names
+   from TYPE, a struct or union type, to the array OUTPUT.  This
+   function assumes that OUTPUT is correctly-sized.  */
+static void
+add_struct_fields (struct type *type, int *nextp, char **output,
+		   char *fieldname, int namelen)
+{
+  int i;
+
+  CHECK_TYPEDEF (type);
+  for (i = 0; i < TYPE_NFIELDS (type); ++i)
+    {
+      if (i < TYPE_N_BASECLASSES (type))
+	add_struct_fields (TYPE_BASECLASS (type, i), nextp, output,
+			   fieldname, namelen);
+      else if (TYPE_FIELD_NAME (type, i)
+	       && ! strncmp (TYPE_FIELD_NAME (type, i), fieldname, namelen))
+	{
+	  output[*nextp] = xstrdup (TYPE_FIELD_NAME (type, i));
+	  ++*nextp;
+	}
+    }
+}
+
+/* Complete on expressions.  Often this means completing on symbol
+   names, but some language parsers also have support for completing
+   field names.  */
+char **
+expression_completer (char *text, char *word)
+{
+  struct type *type;
+  char *fieldname;
+
+  /* Perform a tentative parse of the expression, to see whether a
+     field completion is required.  */
+  fieldname = NULL;
+  type = parse_field_expression (text, &fieldname);
+  if (fieldname && type)
+    {
+      for (;;)
+	{
+	  CHECK_TYPEDEF (type);
+	  if (TYPE_CODE (type) != TYPE_CODE_PTR
+	      && TYPE_CODE (type) != TYPE_CODE_REF)
+	    break;
+	  type = TYPE_TARGET_TYPE (type);
+	}
+
+      if (TYPE_CODE (type) == TYPE_CODE_UNION
+	  || TYPE_CODE (type) == TYPE_CODE_STRUCT)
+	{
+	  int alloc = count_struct_fields (type);
+	  int flen = strlen (fieldname);
+	  int out = 0;
+	  char **result = (char **) xmalloc ((alloc + 1) * sizeof (char *));
+
+	  add_struct_fields (type, &out, result, fieldname, flen);
+	  result[out] = NULL;
+	  return result;
+	}
+    }
+
+  /* Not ideal but it is what we used to do before... */
+  return location_completer (text, word);
+}
+
 /* Complete on command names.  Used by "help".  */
 char **
 command_completer (char *text, char *word)
@@ -520,7 +604,8 @@ complete_line (const char *text, char *line_buffer, int point)
 		      rl_completer_word_break_characters =
 			gdb_completer_file_name_break_characters;
 		    }
-		  else if (c->completer == location_completer)
+		  else if (c->completer == location_completer
+			   || c->completer == expression_completer)
 		    {
 		      /* Commands which complete on locations want to
 			 see the entire argument.  */
@@ -588,7 +673,8 @@ complete_line (const char *text, char *line_buffer, int point)
 		  rl_completer_word_break_characters =
 		    gdb_completer_file_name_break_characters;
 		}
-	      else if (c->completer == location_completer)
+	      else if (c->completer == location_completer
+		       || c->completer == expression_completer)
 		{
 		  for (p = word;
 		       p > tmp_command
diff --git a/gdb/completer.h b/gdb/completer.h
index de311c4..318594e 100644
--- a/gdb/completer.h
+++ b/gdb/completer.h
@@ -25,6 +25,8 @@ extern char **noop_completer (char *, char *);
 
 extern char **filename_completer (char *, char *);
 
+extern char **expression_completer (char *, char *);
+
 extern char **location_completer (char *, char *);
 
 extern char **command_completer (char *, char *);
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index a6f98e6..c249253 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,7 @@
+2008-06-06  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.texinfo (Completion): Add field name example.
+
 2008-06-06  Marc Khouzam  <marc.khouzam@ericsson.com>
 
 	* gdb.texinfo (GDB/MI Program Context): Added example
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 9915ea1..5cef05b 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -1,6 +1,6 @@
 \input texinfo      @c -*-texinfo-*-
 @c Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,
-@c 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+@c 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008
 @c Free Software Foundation, Inc.
 @c
 @c %**start of header
@@ -1531,6 +1531,44 @@ Expressions, ,C@t{++} Expressions}.  You can use the command @code{set
 overload-resolution off} to disable overload resolution;
 see @ref{Debugging C Plus Plus, ,@value{GDBN} Features for C@t{++}}.
 
+@cindex completion of structure field names
+@cindex structure field name completion
+@cindex completion of union field names
+@cindex union field name completion
+When completing in an expression which looks up a field in a
+structure, @value{GDBN} also tries@footnote{The completer can be
+confused by certain kinds of invalid expressions.  Also, it only
+examines the static type of the expression, not the dynamic type.} to
+limit completions to the field names available in the type of the
+left-hand-side:
+
+@smallexample
+(@value{GDBP}) p gdb_stdout.@kbd{M-?}
+magic      to_delete  to_fputs   to_put     to_rewind  
+to_data    to_flush   to_isatty  to_read    to_write   
+@end smallexample
+
+@noindent
+This is because the @code{gdb_stdout} is a variable of the type
+@code{struct ui_file} that is defined in @value{GDBN} sources as
+follows:
+
+@smallexample
+struct ui_file
+@{
+   int *magic;
+   ui_file_flush_ftype *to_flush;
+   ui_file_write_ftype *to_write;
+   ui_file_fputs_ftype *to_fputs;
+   ui_file_read_ftype *to_read;
+   ui_file_delete_ftype *to_delete;
+   ui_file_isatty_ftype *to_isatty;
+   ui_file_rewind_ftype *to_rewind;
+   ui_file_put_ftype *to_put;
+   void *to_data;
+@}
+@end smallexample
+
 
 @node Help
 @section Getting Help
diff --git a/gdb/eval.c b/gdb/eval.c
index 97503c3..bbd7539 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -175,6 +175,36 @@ evaluate_type (struct expression *exp)
   return evaluate_subexp (NULL_TYPE, exp, &pc, EVAL_AVOID_SIDE_EFFECTS);
 }
 
+/* Evaluate a subexpression, avoiding all memory references and
+   getting a value whose type alone is correct.  */
+
+struct value *
+evaluate_subexpression_type (struct expression *exp, int subexp)
+{
+  return evaluate_subexp (NULL_TYPE, exp, &subexp, EVAL_AVOID_SIDE_EFFECTS);
+}
+
+/* Extract a field operation from an expression.  If the subexpression
+   of EXP starting at *SUBEXP is not a structure dereference
+   operation, return NULL.  Otherwise, return the name of the
+   dereferenced field, and advance *SUBEXP to point to the
+   subexpression of the left-hand-side of the dereference.  This is
+   used when completing field names.  */
+
+char *
+extract_field_op (struct expression *exp, int *subexp)
+{
+  int tem;
+  char *result;
+  if (exp->elts[*subexp].opcode != STRUCTOP_STRUCT
+      && exp->elts[*subexp].opcode != STRUCTOP_PTR)
+    return NULL;
+  tem = longest_to_int (exp->elts[*subexp + 1].longconst);
+  result = &exp->elts[*subexp + 2].string;
+  (*subexp) += 1 + 3 + BYTES_TO_EXP_ELEM (tem + 1);
+  return result;
+}
+
 /* If the next expression is an OP_LABELED, skips past it,
    returning the label.  Otherwise, does nothing and returns NULL. */
 
diff --git a/gdb/expression.h b/gdb/expression.h
index 0085b99..084c70e 100644
--- a/gdb/expression.h
+++ b/gdb/expression.h
@@ -389,8 +389,14 @@ struct expression
 
 extern struct expression *parse_expression (char *);
 
+extern struct type *parse_field_expression (char *, char **);
+
 extern struct expression *parse_exp_1 (char **, struct block *, int);
 
+/* For use by parsers; set if we want to parse an expression and
+   attempt to complete a field name.  */
+extern int in_parse_field;
+
 /* The innermost context required by the stack and register variables
    we've encountered so far.  To use this, set it to NULL, then call
    parse_<whatever>, then look at it.  */
diff --git a/gdb/parse.c b/gdb/parse.c
index 09ceaa9..b587ec3 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -52,6 +52,7 @@
 #include "block.h"
 #include "source.h"
 #include "objfiles.h"
+#include "exceptions.h"
 
 /* Standard set of definitions for printing, dumping, prefixifying,
  * and evaluating expressions.  */
@@ -80,6 +81,15 @@ char *prev_lexptr;
 int paren_depth;
 int comma_terminates;
 
+/* True if parsing an expression to find a field reference.  This is
+   only used by completion.  */
+int in_parse_field;
+
+/* The index of the last struct expression directly before a '.' or
+   '->'.  This is set when parsing and is only used when completing a
+   field name.  It is -1 if no dereference operation was found.  */
+static int expout_last_struct = -1;
+
 /* A temporary buffer for identifiers, so we can null-terminate them.
 
    We allocate this with xrealloc.  parse_exp_1 used to allocate with
@@ -100,13 +110,13 @@ show_expressiondebug (struct ui_file *file, int from_tty,
 
 static void free_funcalls (void *ignore);
 
-static void prefixify_expression (struct expression *);
+static int prefixify_expression (struct expression *);
 
-static void prefixify_subexp (struct expression *, struct expression *, int,
-			      int);
+static int prefixify_subexp (struct expression *, struct expression *, int,
+			     int);
 
 static struct expression *parse_exp_in_context (char **, struct block *, int, 
-						int);
+						int, int *);
 
 void _initialize_parse (void);
 
@@ -460,6 +470,16 @@ write_exp_msymbol (struct minimal_symbol *msymbol,
     }
   write_exp_elt_opcode (UNOP_MEMVAL);
 }
+
+/* Mark the current index as the starting location of a structure
+   expression.  This is used when completing on field names.  */
+
+void
+mark_struct_expression (void)
+{
+  expout_last_struct = expout_ptr;
+}
+
 
 /* Recognize tokens that start with '$'.  These include:
 
@@ -664,9 +684,13 @@ copy_name (struct stoken token)
 }
 
 /* Reverse an expression from suffix form (in which it is constructed)
-   to prefix form (in which we can conveniently print or execute it).  */
+   to prefix form (in which we can conveniently print or execute it).
+   Ordinarily this always returns -1.  However, if EXPOUT_LAST_STRUCT
+   is not -1 (i.e., we are trying to complete a field name), it will
+   return the index of the subexpression which is the left-hand-side
+   of the struct operation at EXPOUT_LAST_STRUCT.  */
 
-static void
+static int
 prefixify_expression (struct expression *expr)
 {
   int len = sizeof (struct expression) + EXP_ELEM_TO_BYTES (expr->nelts);
@@ -678,7 +702,7 @@ prefixify_expression (struct expression *expr)
   /* Copy the original expression into temp.  */
   memcpy (temp, expr, len);
 
-  prefixify_subexp (temp, expr, inpos, outpos);
+  return prefixify_subexp (temp, expr, inpos, outpos);
 }
 
 /* Return the number of exp_elements in the postfix subexpression 
@@ -875,9 +899,12 @@ operator_length_standard (struct expression *expr, int endpos,
 
 /* Copy the subexpression ending just before index INEND in INEXPR
    into OUTEXPR, starting at index OUTBEG.
-   In the process, convert it from suffix to prefix form.  */
+   In the process, convert it from suffix to prefix form.
+   If EXPOUT_LAST_STRUCT is -1, then this function always returns -1.
+   Otherwise, it returns the index of the subexpression which is the
+   left-hand-side of the expression at EXPOUT_LAST_STRUCT.  */
 
-static void
+static int
 prefixify_subexp (struct expression *inexpr,
 		  struct expression *outexpr, int inend, int outbeg)
 {
@@ -886,6 +913,7 @@ prefixify_subexp (struct expression *inexpr,
   int i;
   int *arglens;
   enum exp_opcode opcode;
+  int result = -1;
 
   operator_length (inexpr, inend, &oplen, &args);
 
@@ -896,6 +924,9 @@ prefixify_subexp (struct expression *inexpr,
 	  EXP_ELEM_TO_BYTES (oplen));
   outbeg += oplen;
 
+  if (expout_last_struct == inend)
+    result = outbeg - oplen;
+
   /* Find the lengths of the arg subexpressions.  */
   arglens = (int *) alloca (args * sizeof (int));
   for (i = args - 1; i >= 0; i--)
@@ -913,11 +944,21 @@ prefixify_subexp (struct expression *inexpr,
      outbeg does similarly in the output.  */
   for (i = 0; i < args; i++)
     {
+      int r;
       oplen = arglens[i];
       inend += oplen;
-      prefixify_subexp (inexpr, outexpr, inend, outbeg);
+      r = prefixify_subexp (inexpr, outexpr, inend, outbeg);
+      if (r != -1)
+	{
+	  /* Return immediately.  We probably have only parsed a
+	     partial expression, so we don't want to try to reverse
+	     the other operands.  */
+	  return r;
+	}
       outbeg += oplen;
     }
+
+  return result;
 }
 
 /* This page contains the two entry points to this file.  */
@@ -935,23 +976,30 @@ prefixify_subexp (struct expression *inexpr,
 struct expression *
 parse_exp_1 (char **stringptr, struct block *block, int comma)
 {
-  return parse_exp_in_context (stringptr, block, comma, 0);
+  return parse_exp_in_context (stringptr, block, comma, 0, NULL);
 }
 
 /* As for parse_exp_1, except that if VOID_CONTEXT_P, then
-   no value is expected from the expression.  */
+   no value is expected from the expression.
+   OUT_SUBEXP is set when attempting to complete a field name; in this
+   case it is set to the index of the subexpression on the
+   left-hand-side of the struct op.  If not doing such completion, it
+   is left untouched.  */
 
 static struct expression *
 parse_exp_in_context (char **stringptr, struct block *block, int comma, 
-		      int void_context_p)
+		      int void_context_p, int *out_subexp)
 {
+  volatile struct gdb_exception except;
   struct cleanup *old_chain;
+  int subexp;
 
   lexptr = *stringptr;
   prev_lexptr = NULL;
 
   paren_depth = 0;
   type_stack_depth = 0;
+  expout_last_struct = -1;
 
   comma_terminates = comma;
 
@@ -986,10 +1034,20 @@ parse_exp_in_context (char **stringptr, struct block *block, int comma,
   expout = (struct expression *)
     xmalloc (sizeof (struct expression) + EXP_ELEM_TO_BYTES (expout_size));
   expout->language_defn = current_language;
-  make_cleanup (free_current_contents, &expout);
 
-  if (current_language->la_parser ())
-    current_language->la_error (NULL);
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      if (current_language->la_parser ())
+	current_language->la_error (NULL);
+    }
+  if (except.reason < 0)
+    {
+      if (! in_parse_field)
+	{
+	  xfree (expout);
+	  throw_exception (except);
+	}
+    }
 
   discard_cleanups (old_chain);
 
@@ -1009,7 +1067,9 @@ parse_exp_in_context (char **stringptr, struct block *block, int comma,
     dump_raw_expression (expout, gdb_stdlog,
 			 "before conversion to prefix form");
 
-  prefixify_expression (expout);
+  subexp = prefixify_expression (expout);
+  if (out_subexp)
+    *out_subexp = subexp;
 
   current_language->la_post_parser (&expout, void_context_p);
 
@@ -1033,6 +1093,45 @@ parse_expression (char *string)
   return exp;
 }
 
+/* Parse STRING as an expression.  If parsing ends in the middle of a
+   field reference, return the type of the left-hand-side of the
+   reference; furthermore, if the parsing ends in the field name,
+   return the field name in *NAME.  In all other cases, return NULL.  */
+
+struct type *
+parse_field_expression (char *string, char **name)
+{
+  struct expression *exp = NULL;
+  struct value *val;
+  int subexp;
+  volatile struct gdb_exception except;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      in_parse_field = 1;
+      exp = parse_exp_in_context (&string, 0, 0, 0, &subexp);
+    }
+  in_parse_field = 0;
+  if (except.reason < 0 || ! exp)
+    return NULL;
+  if (expout_last_struct == -1)
+    {
+      xfree (exp);
+      return NULL;
+    }
+
+  *name = extract_field_op (exp, &subexp);
+  if (!*name)
+    {
+      xfree (exp);
+      return NULL;
+    }
+  val = evaluate_subexpression_type (exp, subexp);
+  xfree (exp);
+
+  return value_type (val);
+}
+
 /* A post-parser that does nothing */
 
 void
diff --git a/gdb/parser-defs.h b/gdb/parser-defs.h
index 3e473c4..f49ff9e 100644
--- a/gdb/parser-defs.h
+++ b/gdb/parser-defs.h
@@ -138,6 +138,8 @@ extern void write_exp_msymbol (struct minimal_symbol *,
 
 extern void write_dollar_variable (struct stoken str);
 
+extern void mark_struct_expression (void);
+
 extern char *find_template_name_end (char *);
 
 extern void start_arglist (void);
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index bbfef3e..e25c73c 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2366,7 +2366,7 @@ Call a function in the program.\n\
 The argument is the function name and arguments, in the notation of the\n\
 current working language.  The result is printed and saved in the value\n\
 history, if it is not void."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
 
   add_cmd ("variable", class_vars, set_command, _("\
 Evaluate expression EXP and assign result to variable VAR, using assignment\n\
@@ -2399,13 +2399,13 @@ resides in memory.\n\
 \n\
 EXP may be preceded with /FMT, where FMT is a format letter\n\
 but no count or size letter (see \"x\" command)."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
   add_com_alias ("p", "print", class_vars, 1);
 
   c = add_com ("inspect", class_vars, inspect_command, _("\
 Same as \"print\" command, except that if you are running in the epoch\n\
 environment, the value is printed in its own window."));
-  set_cmd_completer (c, location_completer);
+  set_cmd_completer (c, expression_completer);
 
   add_setshow_uinteger_cmd ("max-symbolic-offset", no_class,
 			    &max_symbolic_offset, _("\
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 917d930..ef42b4d 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2008-06-06  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.base/break1.c (struct some_struct): New struct.
+	(values): New global.
+	* gdb.base/completion.exp: Add field name completion test.
+
 2008-06-06  Paul Pluzhnikov  <ppluzhnikov@google.com>
 
 	* gdb.cp/call-c.exp: Test for incorrect handling of reference
diff --git a/gdb/testsuite/gdb.base/break1.c b/gdb/testsuite/gdb.base/break1.c
index 3272cbd..9cbcd30 100644
--- a/gdb/testsuite/gdb.base/break1.c
+++ b/gdb/testsuite/gdb.base/break1.c
@@ -41,3 +41,12 @@ int marker2 (a) int a; { return (1); }	/* set breakpoint 9 here */
 void marker3 (a, b) char *a, *b; {}	/* set breakpoint 18 here */
 void marker4 (d) long d; {}		/* set breakpoint 13 here */
 #endif
+
+/* A structure we use for field name completion tests.  */
+struct some_struct
+{
+  int a_field;
+  int b_field;
+};
+
+struct some_struct values[50];
diff --git a/gdb/testsuite/gdb.base/completion.exp b/gdb/testsuite/gdb.base/completion.exp
index 09f04df..79f588b 100644
--- a/gdb/testsuite/gdb.base/completion.exp
+++ b/gdb/testsuite/gdb.base/completion.exp
@@ -637,6 +637,22 @@ gdb_expect  {
     timeout { fail "(timeout) complete (2) 'p no_var_named_this-'" }
 }
 
+send_gdb "p values\[0\].a\t"
+sleep 3
+gdb_expect  {
+        -re "^p values.0..a_field $"\
+            { send_gdb "\n"
+	      sleep 1
+              gdb_expect {
+                      -re "^.* = 0.*$gdb_prompt $"\
+                                        { pass "complete 'p values\[0\].a'"}
+                      -re ".*$gdb_prompt $" { fail "complete 'p values\[0\].a'"}
+                      timeout           {fail "(timeout) complete 'p values\[0\].a'"}
+                     }
+            }
+        -re ".*$gdb_prompt $"       { fail "complete 'p values\[0\].a'" }
+        timeout         { fail "(timeout) complete 'p values\[0\].a' 2" }
+        }
 
 # The following tests used to simply try to complete `${objdir}/file',
 # and so on.  The problem is that ${objdir} can be very long; the
diff --git a/gdb/value.h b/gdb/value.h
index fa42965..2aac9b2d 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -420,6 +420,11 @@ extern struct value *evaluate_expression (struct expression *exp);
 
 extern struct value *evaluate_type (struct expression *exp);
 
+extern struct value *evaluate_subexpression_type (struct expression *exp,
+						  int subexp);
+
+extern char *extract_field_op (struct expression *exp, int *subexp);
+
 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 						    int *, enum noside);