[gdb/breakpoint] Handle setting breakpoint on label without address

Consider test-case test.c:
...
$ cat test.c
int main (void) {
  return 0;
 L1:
  (void)0;
}
...

Compiled with debug info:
...
$ gcc test.c -g
...

When attempting to set a breakpoint at L1, which is a label without address:
...
 <1><f4>: Abbrev Number: 2 (DW_TAG_subprogram)
    <f5>   DW_AT_name        : main
 <2><115>: Abbrev Number: 3 (DW_TAG_label)
    <116>   DW_AT_name        : L1
    <119>   DW_AT_decl_file   : 1
    <11a>   DW_AT_decl_line   : 5
 <2><11b>: Abbrev Number: 0
...
we run into an internal-error:
...
$ gdb -batch a.out -ex "b main:L1"
linespec.c:3233: internal-error: void \
  decode_line_full(const event_location*, int, program_space*, symtab*, \
  int, linespec_result*, const char*, const char*): \
  Assertion `result.size () == 1 || canonical->pre_expanded' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
...

Fix this by detecting the error condition in decode_line_full instead, and
throwing an error, such that we have instead:
...
(gdb) b main:L1
Location main:L1 not available
(gdb)
...

Unfortunately, to call event_location_to_string, which is used to get the
location name in the error message, we need to pass a non-const struct
event_location, because the call may cache the string in the struct (See
EL_STRING).  So, we change the prototype of decode_line_full accordingly, and
everywhere this propages to.

Tested on x86_64-linux.

gdb/ChangeLog:

2020-08-28  Tom de Vries  <tdevries@suse.de>

	PR breakpoint/26544
	* breakpoint.c (parse_breakpoint_sals): Remove const from struct
	event_location.
	(create_breakpoint): Same.
	(base_breakpoint_decode_location): Same.
	(bkpt_create_sals_from_location): Same.
	(bkpt_decode_location): Same.
	(bkpt_probe_create_sals_from_location): Same.
	(bkpt_probe_decode_location): Same.
	(tracepoint_create_sals_from_location): Same.
	(tracepoint_decode_location): Same.
	(tracepoint_probe_decode_location): Same.
	(strace_marker_create_sals_from_location): Same.
	(strace_marker_decode_location): Same.
	(create_sals_from_location_default): Same.
	(decode_location_default): Same.
	* breakpoint.h (struct breakpoint_ops): Same.
	(create_breakpoint): Same.
	* linespec.h (decode_line_full): Same.
	* linespec.c (decode_line_full): Same.  Throw error if
	result.size () == 0.

gdb/testsuite/ChangeLog:

2020-08-28  Tom de Vries  <tdevries@suse.de>

	* gdb.base/label-without-address.c: New test.
	* gdb.base/label-without-address.exp: New file.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0a1b55fb69ab8a7dc19dfcf27095c733b1de0569..034c95ac31c8404d30cba914de46863797f1bb68 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,27 @@
+2020-08-28  Tom de Vries  <tdevries@suse.de>
+
+       PR breakpoint/26544
+       * breakpoint.c (parse_breakpoint_sals): Remove const from struct
+       event_location.
+       (create_breakpoint): Same.
+       (base_breakpoint_decode_location): Same.
+       (bkpt_create_sals_from_location): Same.
+       (bkpt_decode_location): Same.
+       (bkpt_probe_create_sals_from_location): Same.
+       (bkpt_probe_decode_location): Same.
+       (tracepoint_create_sals_from_location): Same.
+       (tracepoint_decode_location): Same.
+       (tracepoint_probe_decode_location): Same.
+       (strace_marker_create_sals_from_location): Same.
+       (strace_marker_decode_location): Same.
+       (create_sals_from_location_default): Same.
+       (decode_location_default): Same.
+       * breakpoint.h (struct breakpoint_ops): Same.
+       (create_breakpoint): Same.
+       * linespec.h (decode_line_full): Same.
+       * linespec.c (decode_line_full): Same.  Throw error if
+       result.size () == 0.
+
 2020-08-27  Pedro Alves  <pedro@palves.net>
 
        PR gdb/26524

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 8f75618bc9d36057aac9fc5a0409a2e1fab6c0b9..670cba0057850a197f1ce8d363b1d0fe7e6414c0 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -89,7 +89,7 @@ static void map_breakpoint_numbers (const char *,
 static void breakpoint_re_set_default (struct breakpoint *);
 
 static void
-  create_sals_from_location_default (const struct event_location *location,
+  create_sals_from_location_default (struct event_location *location,
                                     struct linespec_result *canonical,
                                     enum bptype type_wanted);
 
@@ -104,7 +104,7 @@ static void create_breakpoints_sal_default (struct gdbarch *,
                                            int, int, int, unsigned);
 
 static std::vector<symtab_and_line> decode_location_default
-  (struct breakpoint *b, const struct event_location *location,
+  (struct breakpoint *b, struct event_location *location,
    struct program_space *search_pspace);
 
 static int can_use_hardware_watchpoint
@@ -8948,7 +8948,7 @@ create_breakpoints_sal (struct gdbarch *gdbarch,
    the caller's responsibility to free them.  */
 
 static void
-parse_breakpoint_sals (const struct event_location *location,
+parse_breakpoint_sals (struct event_location *location,
                       struct linespec_result *canonical)
 {
   struct symtab_and_line cursal;
@@ -9213,7 +9213,7 @@ breakpoint_ops_for_event_location (const struct event_location *location,
 
 int
 create_breakpoint (struct gdbarch *gdbarch,
-                  const struct event_location *location,
+                  struct event_location *location,
                   const char *cond_string,
                   int thread, const char *extra_string,
                   int parse_extra,
@@ -12266,7 +12266,7 @@ base_breakpoint_print_recreate (struct breakpoint *b, struct ui_file *fp)
 
 static void
 base_breakpoint_create_sals_from_location
-  (const struct event_location *location,
+  (struct event_location *location,
    struct linespec_result *canonical,
    enum bptype type_wanted)
 {
@@ -12291,7 +12291,7 @@ base_breakpoint_create_breakpoints_sal (struct gdbarch *gdbarch,
 
 static std::vector<symtab_and_line>
 base_breakpoint_decode_location (struct breakpoint *b,
-                                const struct event_location *location,
+                                struct event_location *location,
                                 struct program_space *search_pspace)
 {
   internal_error_pure_virtual_called ();
@@ -12514,7 +12514,7 @@ bkpt_print_recreate (struct breakpoint *tp, struct ui_file *fp)
 }
 
 static void
-bkpt_create_sals_from_location (const struct event_location *location,
+bkpt_create_sals_from_location (struct event_location *location,
                                struct linespec_result *canonical,
                                enum bptype type_wanted)
 {
@@ -12545,7 +12545,7 @@ bkpt_create_breakpoints_sal (struct gdbarch *gdbarch,
 
 static std::vector<symtab_and_line>
 bkpt_decode_location (struct breakpoint *b,
-                     const struct event_location *location,
+                     struct event_location *location,
                      struct program_space *search_pspace)
 {
   return decode_location_default (b, location, search_pspace);
@@ -12718,7 +12718,7 @@ bkpt_probe_remove_location (struct bp_location *bl,
 }
 
 static void
-bkpt_probe_create_sals_from_location (const struct event_location *location,
+bkpt_probe_create_sals_from_location (struct event_location *location,
                                      struct linespec_result *canonical,
                                      enum bptype type_wanted)
 {
@@ -12732,7 +12732,7 @@ bkpt_probe_create_sals_from_location (const struct event_location *location,
 
 static std::vector<symtab_and_line>
 bkpt_probe_decode_location (struct breakpoint *b,
-                           const struct event_location *location,
+                           struct event_location *location,
                            struct program_space *search_pspace)
 {
   std::vector<symtab_and_line> sals = parse_probes (location, search_pspace, NULL);
@@ -12826,7 +12826,7 @@ tracepoint_print_recreate (struct breakpoint *self, struct ui_file *fp)
 }
 
 static void
-tracepoint_create_sals_from_location (const struct event_location *location,
+tracepoint_create_sals_from_location (struct event_location *location,
                                      struct linespec_result *canonical,
                                      enum bptype type_wanted)
 {
@@ -12857,7 +12857,7 @@ tracepoint_create_breakpoints_sal (struct gdbarch *gdbarch,
 
 static std::vector<symtab_and_line>
 tracepoint_decode_location (struct breakpoint *b,
-                           const struct event_location *location,
+                           struct event_location *location,
                            struct program_space *search_pspace)
 {
   return decode_location_default (b, location, search_pspace);
@@ -12869,7 +12869,7 @@ struct breakpoint_ops tracepoint_breakpoint_ops;
 
 static void
 tracepoint_probe_create_sals_from_location
-  (const struct event_location *location,
+  (struct event_location *location,
    struct linespec_result *canonical,
    enum bptype type_wanted)
 {
@@ -12879,7 +12879,7 @@ tracepoint_probe_create_sals_from_location
 
 static std::vector<symtab_and_line>
 tracepoint_probe_decode_location (struct breakpoint *b,
-                                 const struct event_location *location,
+                                 struct event_location *location,
                                  struct program_space *search_pspace)
 {
   /* We use the same method for breakpoint on probes.  */
@@ -12960,7 +12960,7 @@ dprintf_after_condition_true (struct bpstats *bs)
    markers (`-m').  */
 
 static void
-strace_marker_create_sals_from_location (const struct event_location *location,
+strace_marker_create_sals_from_location (struct event_location *location,
                                         struct linespec_result *canonical,
                                         enum bptype type_wanted)
 {
@@ -13030,7 +13030,7 @@ strace_marker_create_breakpoints_sal (struct gdbarch *gdbarch,
 
 static std::vector<symtab_and_line>
 strace_marker_decode_location (struct breakpoint *b,
-                              const struct event_location *location,
+                              struct event_location *location,
                               struct program_space *search_pspace)
 {
   struct tracepoint *tp = (struct tracepoint *) b;
@@ -13713,7 +13713,7 @@ breakpoint_re_set_default (struct breakpoint *b)
    calls parse_breakpoint_sals.  Return 1 for success, zero for failure.  */
 
 static void
-create_sals_from_location_default (const struct event_location *location,
+create_sals_from_location_default (struct event_location *location,
                                   struct linespec_result *canonical,
                                   enum bptype type_wanted)
 {
@@ -13750,7 +13750,7 @@ create_breakpoints_sal_default (struct gdbarch *gdbarch,
 
 static std::vector<symtab_and_line>
 decode_location_default (struct breakpoint *b,
-                        const struct event_location *location,
+                        struct event_location *location,
                         struct program_space *search_pspace)
 {
   struct linespec_result canonical;

diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 347aeb75f301972d1e39e9fcf801cc1008dec4af..a5fead914922ef83a9df68e008867d69077e35db 100644 (file)
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -609,7 +609,7 @@ struct breakpoint_ops
      `create_sals_from_location_default'.
 
      This function is called inside `create_breakpoint'.  */
-  void (*create_sals_from_location) (const struct event_location *location,
+  void (*create_sals_from_location) (struct event_location *location,
                                     struct linespec_result *canonical,
                                     enum bptype type_wanted);
 
@@ -636,7 +636,7 @@ struct breakpoint_ops
      This function is called inside `location_to_sals'.  */
   std::vector<symtab_and_line> (*decode_location)
     (struct breakpoint *b,
-     const struct event_location *location,
+     struct event_location *location,
      struct program_space *search_pspace);
 
   /* Return true if this breakpoint explains a signal.  See
@@ -1386,7 +1386,7 @@ enum breakpoint_create_flags
    Returns true if any breakpoint was created; false otherwise.  */
 
 extern int create_breakpoint (struct gdbarch *gdbarch,
-                             const struct event_location *location,
+                             struct event_location *location,
                              const char *cond_string, int thread,
                              const char *extra_string,
                              int parse_extra,

diff --git a/gdb/linespec.c b/gdb/linespec.c
index 4a634e3aff98e3240d2eb0486e16a68f9729f08c..e8f3d594c3a03d2d15347de7e822b07c877c402c 100644 (file)
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3201,7 +3201,7 @@ event_location_to_sals (linespec_parser *parser,
 /* See linespec.h.  */
 
 void
-decode_line_full (const struct event_location *location, int flags,
+decode_line_full (struct event_location *location, int flags,
                  struct program_space *search_pspace,
                  struct symtab *default_symtab,
                  int default_line, struct linespec_result *canonical,
@@ -3230,6 +3230,10 @@ decode_line_full (const struct event_location *location, int flags,
                                                                location);
   state = PARSER_STATE (&parser);
 
+  if (result.size () == 0)
+    throw_error (NOT_SUPPORTED_ERROR, _("Location %s not available"),
+                event_location_to_string (location));
+
   gdb_assert (result.size () == 1 || canonical->pre_expanded);
   canonical->pre_expanded = 1;
 

diff --git a/gdb/linespec.h b/gdb/linespec.h
index 2a34f60f05dba08f830baffa3a4e33aa7ca52b51..9c2c8988fbcd5c58c0c7c8f0e737a52eb93f0da4 100644 (file)
--- a/gdb/linespec.h
+++ b/gdb/linespec.h
@@ -124,7 +124,7 @@ extern std::vector<symtab_and_line>
    strcmp sense) to FILTER will be returned; all others will be
    filtered out.  */
 
-extern void decode_line_full (const struct event_location *location, int flags,
+extern void decode_line_full (struct event_location *location, int flags,
                              struct program_space *search_pspace,
                              struct symtab *default_symtab, int default_line,
                              struct linespec_result *canonical,

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 6ce2b71b7464e20ad0f668b7625118c701e2c66b..6335ece30d754b340c6d9df320617ed87426eb3d 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-08-28  Tom de Vries  <tdevries@suse.de>
+
+       * gdb.base/label-without-address.c: New test.
+       * gdb.base/label-without-address.exp: New file.
+
 2020-08-27  Pedro Alves  <pedro@palves.net>
 
        PR gdb/26523

diff --git a/gdb/testsuite/gdb.base/label-without-address.c b/gdb/testsuite/gdb.base/label-without-address.c
new file mode 100644 (file)
index 0000000..f0d4a42
--- /dev/null
+++ b/gdb/testsuite/gdb.base/label-without-address.c
@@ -0,0 +1,24 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2020 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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+int
+main (void)
+{
+  return 0;
+ L1:
+  (void)0;
+}

diff --git a/gdb/testsuite/gdb.base/label-without-address.exp b/gdb/testsuite/gdb.base/label-without-address.exp
new file mode 100644 (file)
index 0000000..0fcb1fd
--- /dev/null
+++ b/gdb/testsuite/gdb.base/label-without-address.exp
@@ -0,0 +1,37 @@
+# Copyright 2020 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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
+    return -1
+}
+
+set supported 0
+gdb_test_multiple "l main:L1" "" {
+    -wrap -re "No label \"L1\" defined in function \"main\"\." {
+       unsupported $gdb_test_name
+    }
+    -wrap -re "L1:\r\n.*" {
+       pass $gdb_test_name
+       set supported 1
+    }
+}
+
+if { ! $supported } {
+    return -1
+}
+
+gdb_test "break main:L1" "Location main:L1 not available"