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Re: Breaking in a c++ method with current language set to c.


Daniel Jacobowitz wrote:
On Mon, Mar 05, 2007 at 03:37:15AM +0000, Pedro Alves wrote:
I've looked at several ways to fix it, and all but this one turned out more
invasive than I hoped for, because current_language is used in a several places
(in symtab.c). Instead, I simply wrapped linespec.c:find_method with a
set_language (lang of A), guarded with a cleanup.

How much invasive? I don't like the global "current language"; like the global "selected frame", it's prone to this sort of problem when we'd really rather be looking at a different language.
As my first approach I had added a new parameter to lookup_symbol, and
changed all the calls throughout to pass the language that seemed to
make sense or current_language otherwise.  I ended up touching many
files I wouldn't be able to test, like fortran, scheme, java and ada
support.  It was more invasive than I could afford :) (,and probably wrong).

As an intermediate step, I came up with this version.  It adds a new
lookup_symbol_in_language, and tweaks a few worker functions to accept
the language by parameter, instead of relying on the current language.
lookup_symbol is then a simple wrapper that passes the current_language
to the new lookup_symbol_in_language.  I needed to tweak ada-lang.c,
because the lookup_symbol_in_language name was already taken  there.  The
approach implemented there was similar to my previous patch, that is, it
temporarily switched the current language [1].  As I don't have an ada
compiler (and I can't fit any on my machine), I can't be be sure I caught
all the hard coded current_language uses, so I've just make the ada
function static and added a FIXME.  Maybe someone will be able to try
with the new version in symtab.c.

What do you think of this approach?

Tested on i686-pc-cygwin, no regressions.

Cheers,
Pedro Alves

[1] http://sourceware.org/ml/gdb-patches/2004-06/msg00152.html


gdb/

	* linespec.c: Include language.h.
	(find_methods): Add language parameter.  Call
	lookup_symbol_in_language.  Pass language down.
	(add_matching_methods): Likewise.  Call
	lookup_symbol_in_language.
	(add_constructors): Likewise.
	(find_method): Pass sym_class to collect_methods.
	(collect_methods): Add sym_class parameter.  Pass language
	down.
	* symtab.c (lookup_symbol): Rename to ...
	(lookup_symbol_in_language): ... this.  Add language
	parameter.  Use passed language instead of current_language.
	(lookup_symbol): New as wrapper around
	lookup_symbol_in_language.
	(lookup_symbol_aux): Add language parameter.  Use passed
	language instead of current_language.
	(search_symbols): Indent.
	* symtab.h (enum language): Forward declare.
	(lookup_symbol_in_language): Declare.
	(lookup_symbol): Update description.
	* ada-lang.h (lookup_symbol_in_language): Remove declaration.
	* ada-lang.c (lookup_symbol_in_language): Rename to ...
	(ada_lookup_symbol_in_language): ... this, and make static.
	(standard_lookup): Call ada_lookup_symbol_in_language.

---
 gdb/ada-lang.c |   19 ++++++++++++++-----
 gdb/ada-lang.h |   11 -----------
 gdb/linespec.c |   36 ++++++++++++++++++++----------------
 gdb/symtab.c   |   52 ++++++++++++++++++++++++++++++++++++----------------
 gdb/symtab.h   |   10 +++++++++-
 5 files changed, 79 insertions(+), 49 deletions(-)

Index: src/gdb/ada-lang.c
===================================================================
--- src.orig/gdb/ada-lang.c	2007-03-09 01:12:02.000000000 +0000
+++ src/gdb/ada-lang.c	2007-03-11 20:42:46.000000000 +0000
@@ -271,6 +271,13 @@ static struct value *ada_evaluate_subexp
 
 static void ada_forward_operator_length (struct expression *, int, int *,
 					 int *);
+
+static struct symbol *ada_lookup_symbol_in_language (const char *,
+						     const struct block *,
+						     domain_enum,
+						     enum language,
+						     int *,
+						     struct symtab **);
 
 
 
@@ -3828,7 +3835,8 @@ standard_lookup (const char *name, const
   if (lookup_cached_symbol (name, domain, &sym, NULL, NULL))
     return sym;
   sym =
-    lookup_symbol_in_language (name, block, domain, language_c, 0, &symtab);
+    ada_lookup_symbol_in_language (name, block, domain, language_c,
+				   0, &symtab);
   cache_symbol (name, domain, sym, block_found, symtab);
   return sym;
 }
@@ -4221,11 +4229,12 @@ restore_language (void *lang)
   set_language ((enum language) lang);
 }
 
-/* As for lookup_symbol, but performed as if the current language 
-   were LANG. */
+/* Look up a symbol by name using the search conventions of
+   a specific language (optional block, optional symtab).
+   FIXME: Should use lookup_symbol_in_language from symtab.c instead.  */
 
-struct symbol *
-lookup_symbol_in_language (const char *name, const struct block *block,
+static struct symbol *
+ada_lookup_symbol_in_language (const char *name, const struct block *block,
                            domain_enum domain, enum language lang,
                            int *is_a_field_of_this, struct symtab **symtab)
 {
Index: src/gdb/linespec.c
===================================================================
--- src.orig/gdb/linespec.c	2007-03-09 01:12:02.000000000 +0000
+++ src/gdb/linespec.c	2007-03-09 01:44:12.000000000 +0000
@@ -37,6 +37,7 @@
 #include "objc-lang.h"
 #include "linespec.h"
 #include "exceptions.h"
+#include "language.h"
 
 /* We share this one with symtab.c, but it is not exported widely. */
 
@@ -74,7 +75,7 @@ static struct symtabs_and_lines find_met
 					     struct type *t,
 					     struct symbol *sym_class);
 
-static int collect_methods (char *copy, struct type *t,
+static int collect_methods (char *copy, struct type *t, struct symbol *sym_class,
 			    struct symbol **sym_arr);
 
 static NORETURN void cplusplus_error (const char *name,
@@ -83,13 +84,14 @@ static NORETURN void cplusplus_error (co
 
 static int total_number_of_methods (struct type *type);
 
-static int find_methods (struct type *, char *, struct symbol **);
+static int find_methods (struct type *, char *, enum language, struct symbol **);
 
 static int add_matching_methods (int method_counter, struct type *t,
+				 enum language language,
 				 struct symbol **sym_arr);
 
 static int add_constructors (int method_counter, struct type *t,
-			     struct symbol **sym_arr);
+			     enum language language, struct symbol **sym_arr);
 
 static void build_canonical_line_spec (struct symtab_and_line *,
 				       char *, char ***);
@@ -196,7 +198,7 @@ total_number_of_methods (struct type *ty
    Note that this function is g++ specific.  */
 
 static int
-find_methods (struct type *t, char *name, struct symbol **sym_arr)
+find_methods (struct type *t, char *name, enum language language, struct symbol **sym_arr)
 {
   int i1 = 0;
   int ibase;
@@ -206,8 +208,8 @@ find_methods (struct type *t, char *name
      unless we figure out how to get the physname without the name of
      the class, then the loop can't do any good.  */
   if (class_name
-      && (lookup_symbol (class_name, (struct block *) NULL,
-			 STRUCT_DOMAIN, (int *) NULL,
+      && (lookup_symbol_in_language (class_name, (struct block *) NULL,
+			 STRUCT_DOMAIN, language, (int *) NULL,
 			 (struct symtab **) NULL)))
     {
       int method_counter;
@@ -238,12 +240,12 @@ find_methods (struct type *t, char *name
 
 	  if (strcmp_iw (name, method_name) == 0)
 	    /* Find all the overloaded methods with that name.  */
-	    i1 += add_matching_methods (method_counter, t,
+	    i1 += add_matching_methods (method_counter, t, language,
 					sym_arr + i1);
 	  else if (strncmp (class_name, name, name_len) == 0
 		   && (class_name[name_len] == '\0'
 		       || class_name[name_len] == '<'))
-	    i1 += add_constructors (method_counter, t,
+	    i1 += add_constructors (method_counter, t, language,
 				    sym_arr + i1);
 	}
     }
@@ -261,7 +263,7 @@ find_methods (struct type *t, char *name
 
   if (i1 == 0)
     for (ibase = 0; ibase < TYPE_N_BASECLASSES (t); ibase++)
-      i1 += find_methods (TYPE_BASECLASS (t, ibase), name, sym_arr + i1);
+      i1 += find_methods (TYPE_BASECLASS (t, ibase), name, language, sym_arr + i1);
 
   return i1;
 }
@@ -271,7 +273,7 @@ find_methods (struct type *t, char *name
    array SYM_ARR.  Return the number of methods added.  */
 
 static int
-add_matching_methods (int method_counter, struct type *t,
+add_matching_methods (int method_counter, struct type *t, enum language language,
 		      struct symbol **sym_arr)
 {
   int field_counter;
@@ -305,8 +307,9 @@ add_matching_methods (int method_counter
       if (is_destructor_name (phys_name) != 0)
 	continue;
 
-      sym_arr[i1] = lookup_symbol (phys_name,
+      sym_arr[i1] = lookup_symbol_in_language (phys_name,
 				   NULL, VAR_DOMAIN,
+				   language,
 				   (int *) NULL,
 				   (struct symtab **) NULL);
       if (sym_arr[i1])
@@ -332,7 +335,7 @@ add_matching_methods (int method_counter
    array SYM_ARR.  Return the number of methods added.  */
 
 static int
-add_constructors (int method_counter, struct type *t,
+add_constructors (int method_counter, struct type *t, enum language language,
 		  struct symbol **sym_arr)
 {
   int field_counter;
@@ -362,8 +365,9 @@ add_constructors (int method_counter, st
 
       /* If this method is actually defined, include it in the
 	 list.  */
-      sym_arr[i1] = lookup_symbol (phys_name,
+      sym_arr[i1] = lookup_symbol_in_language (phys_name,
 				   NULL, VAR_DOMAIN,
+				   language,
 				   (int *) NULL,
 				   (struct symtab **) NULL);
       if (sym_arr[i1])
@@ -1410,7 +1414,7 @@ find_method (int funfirstline, char ***c
   /* Find all methods with a matching name, and put them in
      sym_arr.  */
 
-  i1 = collect_methods (copy, t, sym_arr);
+  i1 = collect_methods (copy, t, sym_class, sym_arr);
 
   if (i1 == 1)
     {
@@ -1465,7 +1469,7 @@ find_method (int funfirstline, char ***c
    them in SYM_ARR.  Return the number of methods found.  */
 
 static int
-collect_methods (char *copy, struct type *t,
+collect_methods (char *copy, struct type *t, struct symbol *sym_class,
 		 struct symbol **sym_arr)
 {
   int i1 = 0;	/*  Counter for the symbol array.  */
@@ -1488,7 +1492,7 @@ collect_methods (char *copy, struct type
 	}
     }
   else
-    i1 = find_methods (t, copy, sym_arr);
+    i1 = find_methods (t, copy, SYMBOL_LANGUAGE (sym_class), sym_arr);
 
   return i1;
 }
Index: src/gdb/symtab.c
===================================================================
--- src.orig/gdb/symtab.c	2007-03-09 01:12:02.000000000 +0000
+++ src/gdb/symtab.c	2007-03-09 01:44:12.000000000 +0000
@@ -84,6 +84,7 @@ static struct symbol *lookup_symbol_aux 
 					 const char *linkage_name,
 					 const struct block *block,
 					 const domain_enum domain,
+					 enum language language,
 					 int *is_a_field_of_this,
 					 struct symtab **symtab);
 
@@ -1079,9 +1080,10 @@ fixup_psymbol_section (struct partial_sy
    code).  */
 
 struct symbol *
-lookup_symbol (const char *name, const struct block *block,
-	       const domain_enum domain, int *is_a_field_of_this,
-	       struct symtab **symtab)
+lookup_symbol_in_language (const char *name, const struct block *block,
+			   const domain_enum domain, enum language lang,
+			   int *is_a_field_of_this,
+			   struct symtab **symtab)
 {
   char *demangled_name = NULL;
   const char *modified_name = NULL;
@@ -1093,7 +1095,7 @@ lookup_symbol (const char *name, const s
 
   /* If we are using C++ or Java, demangle the name before doing a lookup, so
      we can always binary search. */
-  if (current_language->la_language == language_cplus)
+  if (lang == language_cplus)
     {
       demangled_name = cplus_demangle (name, DMGL_ANSI | DMGL_PARAMS);
       if (demangled_name)
@@ -1103,7 +1105,7 @@ lookup_symbol (const char *name, const s
 	  needtofreename = 1;
 	}
     }
-  else if (current_language->la_language == language_java)
+  else if (lang == language_java)
     {
       demangled_name = cplus_demangle (name, 
 		      		       DMGL_ANSI | DMGL_PARAMS | DMGL_JAVA);
@@ -1129,7 +1131,8 @@ lookup_symbol (const char *name, const s
     }
 
   returnval = lookup_symbol_aux (modified_name, mangled_name, block,
-				 domain, is_a_field_of_this, symtab);
+				 domain, lang,
+				 is_a_field_of_this, symtab);
   if (needtofreename)
     xfree (demangled_name);
 
@@ -1140,7 +1143,20 @@ lookup_symbol (const char *name, const s
   return returnval;	 
 }
 
-/* Behave like lookup_symbol_aux except that NAME is the natural name
+/* Behave like lookup_symbol_in_language, but performed with the
+   current language. */
+
+struct symbol *
+lookup_symbol (const char *name, const struct block *block,
+	       domain_enum domain, int *is_a_field_of_this,
+	       struct symtab **symtab)
+{
+  return lookup_symbol_in_language (name, block, domain,
+				    current_language->la_language,
+				    is_a_field_of_this, symtab);
+}
+
+/* Behave like lookup_symbol except that NAME is the natural name
    of the symbol that we're looking for and, if LINKAGE_NAME is
    non-NULL, ensure that the symbol's linkage name matches as
    well.  */
@@ -1148,9 +1164,11 @@ lookup_symbol (const char *name, const s
 static struct symbol *
 lookup_symbol_aux (const char *name, const char *linkage_name,
 		   const struct block *block, const domain_enum domain,
+		   enum language language,
 		   int *is_a_field_of_this, struct symtab **symtab)
 {
   struct symbol *sym;
+  const struct language_defn *langdef;
 
   /* Make sure we do something sensible with is_a_field_of_this, since
      the callers that set this parameter to some non-null value will
@@ -1168,13 +1186,15 @@ lookup_symbol_aux (const char *name, con
   if (sym != NULL)
     return sym;
 
-  /* If requested to do so by the caller and if appropriate for the
-     current language, check to see if NAME is a field of `this'. */
+  /* If requested to do so by the caller and if appropriate for LANGUAGE,
+     check to see if NAME is a field of `this'. */
+
+  langdef = language_def (language);
 
-  if (current_language->la_value_of_this != NULL
+  if (langdef->la_value_of_this != NULL
       && is_a_field_of_this != NULL)
     {
-      struct value *v = current_language->la_value_of_this (0);
+      struct value *v = langdef->la_value_of_this (0);
 
       if (v && check_field (v, name))
 	{
@@ -1185,12 +1205,11 @@ lookup_symbol_aux (const char *name, con
 	}
     }
 
-  /* Now do whatever is appropriate for the current language to look
+  /* Now do whatever is appropriate for LANGUAGE to look
      up static and global variables.  */
 
-  sym = current_language->la_lookup_symbol_nonlocal (name, linkage_name,
-						     block, domain,
-						     symtab);
+  sym = langdef->la_lookup_symbol_nonlocal (name, linkage_name,
+					     block, domain, symtab);
   if (sym != NULL)
     return sym;
 
@@ -3070,7 +3089,8 @@ search_symbols (char *regexp, domain_enu
 			|| lookup_symbol (SYMBOL_LINKAGE_NAME (msymbol),
 					  (struct block *) NULL,
 					  VAR_DOMAIN,
-					0, (struct symtab **) NULL) == NULL)
+					  0, (struct symtab **) NULL)
+			== NULL)
 		      found_misc = 1;
 		  }
 	      }
Index: src/gdb/symtab.h
===================================================================
--- src.orig/gdb/symtab.h	2007-03-09 01:12:02.000000000 +0000
+++ src/gdb/symtab.h	2007-03-09 01:44:12.000000000 +0000
@@ -34,6 +34,7 @@ struct block;
 struct blockvector;
 struct axs_value;
 struct agent_expr;
+enum language;
 
 /* Some of the structures in this file are space critical.
    The space-critical structures are:
@@ -1007,7 +1008,14 @@ extern int asm_demangle;
 
 extern struct symtab *lookup_symtab (const char *);
 
-/* lookup a symbol by name (optional block, optional symtab) */
+/* lookup a symbol by name (optional block, optional symtab) in language */
+
+extern struct symbol *lookup_symbol_in_language (const char *, const struct block *,
+						 const domain_enum, enum language,
+						 int *,
+						 struct symtab **);
+
+/* lookup a symbol by name (optional block, optional symtab) in the current language */
 
 extern struct symbol *lookup_symbol (const char *, const struct block *,
 				     const domain_enum, int *,
Index: src/gdb/ada-lang.h
===================================================================
--- src.orig/gdb/ada-lang.h	2007-03-09 01:12:02.000000000 +0000
+++ src/gdb/ada-lang.h	2007-03-09 01:44:12.000000000 +0000
@@ -474,17 +474,6 @@ extern void ada_reset_thread_registers (
 
 extern int ada_build_task_list (void);
 
-/* Look up a symbol by name using the search conventions of 
-   a specific language (optional block, optional symtab). 
-   FIXME: Should be symtab.h. */
-
-extern struct symbol *lookup_symbol_in_language (const char *, 
-						 const struct block *,
-						 domain_enum, 
-						 enum language,
-						 int *,
-						 struct symtab **);
-
 extern int ada_exception_catchpoint_p (struct breakpoint *b);
   
 extern struct symtab_and_line


gdb/testsuite/

	* gdb.cp/method2.cc: New test.
	* gdb.cp/method2.exp: New test.
	* gdb.cp/Makefile.in (EXECUTABLES): Add method2.

---
 gdb/testsuite/gdb.cp/Makefile.in |    2 -
 gdb/testsuite/gdb.cp/method2.cc  |   27 +++++++++++++++
 gdb/testsuite/gdb.cp/method2.exp |   70 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 98 insertions(+), 1 deletion(-)

Index: src/gdb/testsuite/gdb.cp/method2.cc
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ src/gdb/testsuite/gdb.cp/method2.cc	2007-03-11 20:39:30.000000000 +0000
@@ -0,0 +1,27 @@
+struct A
+{
+  void method ();
+  void method (int a);
+  void method (A* a);
+};
+
+void
+A::method ()
+{
+}
+
+void
+A::method (int a)
+{
+}
+
+void
+A::method (A* a)
+{
+}
+
+int
+main (int argc, char** argv)
+{
+  return 0;
+}
Index: src/gdb/testsuite/gdb.cp/method2.exp
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ src/gdb/testsuite/gdb.cp/method2.exp	2007-03-11 20:39:30.000000000 +0000
@@ -0,0 +1,70 @@
+# Copyright 2007
+# Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+# This file is part of the gdb testsuite
+
+# This tests setting a break in an ambiguous c++ method with
+# current_language set to c.
+
+if { [skip_cplus_tests] } { continue }
+
+set testfile "method2"
+set srcfile ${testfile}.cc
+set binfile ${objdir}/${subdir}/${testfile}
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug c++}] != "" } {
+     untested method2.exp
+     return -1
+}
+
+if [get_compiler_info $binfile "c++"] {
+  return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if ![runto_main] then {
+    perror "couldn't run to breakpoint"
+    continue
+}
+
+proc test_break { lang } {
+    global gdb_prompt
+
+    gdb_test "set lang $lang" \
+	"" \
+	"setting language $lang"
+
+    send_gdb "break A::method\n"
+    gdb_expect {
+	-re ".0. cancel.*\[\r\n\]*.1. all.*\[\r\n\]*.2. A::method\\(A\\*\\) at .*\[\r\n\]*.3. A::method\\(int\\) at .*\[\r\n\]*\[\r\n\]*.4. A::method\\(\\) at .*\[\r\n\]*> $" {
+	    gdb_test "0" \
+		"canceled" \
+		"breaking in method ($lang)"
+	}
+	-re ".*$gdb_prompt $" { fail "breaking in method ($lang)" }
+	default { fail "breaking in method ($lang) (timeout)" }
+    }
+}
+
+test_break "c"
+test_break "c++"
+
+gdb_continue_to_end "continue to end"
Index: src/gdb/testsuite/gdb.cp/Makefile.in
===================================================================
--- src.orig/gdb/testsuite/gdb.cp/Makefile.in	2007-03-05 03:28:38.000000000 +0000
+++ src/gdb/testsuite/gdb.cp/Makefile.in	2007-03-11 20:39:30.000000000 +0000
@@ -4,7 +4,7 @@ srcdir = @srcdir@
 EXECUTABLES = ambiguous annota2 anon-union cplusfuncs cttiadd \
 	derivation inherit local member-ptr method misc \
         overload ovldbreak ref-typ ref-typ2 templates userdef virtfunc namespace \
-	ref-types ref-params
+	ref-types ref-params method2
 
 all info install-info dvi install uninstall installcheck check:
 	@echo "Nothing to be done for $@..."



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