[Bug breakpoints/26544] New: linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[Bug breakpoints/26544] New: linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

            Bug ID: 26544
           Summary: linespec.c:3233: internal-error: void decode_line_full
                    (): Assertion `result.size () == 1 ||
                    canonical->pre_expanded' failed.
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: breakpoints
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Created attachment 12805
  --> https://sourceware.org/bugzilla/attachment.cgi?id=12805&action=edit
patch to make test-case trigger internal-error

[ Looks like a duplicate of PR25067. ]

Using the attached patch on test-case gdb.base/eh_return.exp, we run into:
...
(gdb) break eh2:here^M
src/gdb/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.^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
...

Also reproduces if we first run to eh2:
...
$ gdb \
    outputs/gdb.base/eh_return/eh_return \
    -batch \
    -ex "b eh2" \
    -ex run \
    -ex "b here"
Breakpoint 1 at 0x4006af: file eh_return.c, line 52.

Breakpoint 1, eh2 (p=0x40071c <continuation>) at eh_return.c:52
52        eh2a (val, val, val, val, val, val, val, val, p);
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.
...

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Minimal reproducer:
...
$ cat test.c
int
main (void)
{
  return 0;
 L1:
  (void)0;
}
...

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

Run like this:
...
$ gdb -batch a.out -ex "b main:L1"
linespec.c:3244: 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.
...

Same result with:
...
$ gdb -batch a.out -ex start -ex "b L1"
...

The problem seems to be a DW_TAG_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
...

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Backtrace at assert:
...
(gdb) bt
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007ffff4b96b01 in __GI_abort () at abort.c:79
#2  0x0000000000a63722 in dump_core () at
/home/vries/gdb_versions/devel/src/gdb/utils.c:204
#3  0x0000000000a63bf4 in internal_vproblem(internal_problem *, const char *,
int, const char *, typedef __va_list_tag __va_list_tag *) (problem=0x1529260
<internal_error_problem>, 
    file=0xde4528 "/home/vries/gdb_versions/devel/src/gdb/linespec.c",
line=3233, 
    fmt=0xde44e1 "%s: Assertion `%s' failed.", ap=0x7fffffffce98)
    at /home/vries/gdb_versions/devel/src/gdb/utils.c:414
#4  0x0000000000a63cc7 in internal_verror (
    file=0xde4528 "/home/vries/gdb_versions/devel/src/gdb/linespec.c",
line=3233, 
    fmt=0xde44e1 "%s: Assertion `%s' failed.", ap=0x7fffffffce98)
    at /home/vries/gdb_versions/devel/src/gdb/utils.c:439
#5  0x0000000000cf1389 in internal_error (
    file=0xde4528 "/home/vries/gdb_versions/devel/src/gdb/linespec.c",
line=3233, 
    fmt=0xde44e1 "%s: Assertion `%s' failed.")
    at /home/vries/gdb_versions/devel/src/gdbsupport/errors.cc:55
#6  0x000000000074c828 in decode_line_full (location=0x2250080, flags=1,
search_pspace=0x0, 
    default_symtab=0x0, default_line=0, canonical=0x7fffffffd410,
select_mode=0x0, 
    filter=0x0) at /home/vries/gdb_versions/devel/src/gdb/linespec.c:3233
#7  0x00000000004daaa4 in parse_breakpoint_sals (location=0x2250080, 
    canonical=0x7fffffffd410) at
/home/vries/gdb_versions/devel/src/gdb/breakpoint.c:9025
#8  0x00000000004e5e02 in create_sals_from_location_default
(location=0x2250080, 
    canonical=0x7fffffffd410, type_wanted=bp_breakpoint)
    at /home/vries/gdb_versions/devel/src/gdb/breakpoint.c:13725
#9  0x00000000004e327c in bkpt_create_sals_from_location (location=0x2250080, 
    canonical=0x7fffffffd410, type_wanted=bp_breakpoint)
    at /home/vries/gdb_versions/devel/src/gdb/breakpoint.c:12526
#10 0x00000000004db3b8 in create_breakpoint (gdbarch=0x2225a80,
location=0x2250080, 
    cond_string=0x0, thread=0, extra_string=0x0, parse_extra=1, tempflag=0, 
    type_wanted=bp_breakpoint, ignore_count=0,
pending_break_support=AUTO_BOOLEAN_AUTO, 
    ops=0x1594380 <bkpt_breakpoint_ops>, from_tty=0, enabled=1, internal=0,
flags=0)
    at /home/vries/gdb_versions/devel/src/gdb/breakpoint.c:9240
#11 0x00000000004dbc5e in break_command_1 (arg=0x7fffffffe1b4 "", flag=0,
from_tty=0)
    at /home/vries/gdb_versions/devel/src/gdb/breakpoint.c:9408
#12 0x00000000004dbf41 in break_command (arg=0x7fffffffe1ad "main:L1",
from_tty=0)
    at /home/vries/gdb_versions/devel/src/gdb/breakpoint.c:9469
#13 0x000000000053b9d0 in do_const_cfunc (c=0x1a9fd00, args=0x7fffffffe1ad
"main:L1", 
    from_tty=0) at /home/vries/gdb_versions/devel/src/gdb/cli/cli-decode.c:95
#14 0x000000000053f1ad in cmd_func (cmd=0x1a9fd00, args=0x7fffffffe1ad
"main:L1", from_tty=0)
    at /home/vries/gdb_versions/devel/src/gdb/cli/cli-decode.c:2181
#15 0x00000000009f2940 in execute_command (p=0x7fffffffe1b3 "1", from_tty=0)
    at /home/vries/gdb_versions/devel/src/gdb/top.c:668
#16 0x000000000078c961 in catch_command_errors (
    command=0x9f23f0 <execute_command(char const*, int)>, arg=0x7fffffffe1ab "b
main:L1", 
    from_tty=0) at /home/vries/gdb_versions/devel/src/gdb/main.c:457
#17 0x000000000078dd0e in captured_main_1 (context=0x7fffffffdb20)
    at /home/vries/gdb_versions/devel/src/gdb/main.c:1219
#18 0x000000000078df4f in captured_main (data=0x7fffffffdb20)
    at /home/vries/gdb_versions/devel/src/gdb/main.c:1243
#19 0x000000000078dfba in gdb_main (args=0x7fffffffdb20)
    at /home/vries/gdb_versions/devel/src/gdb/main.c:1268
#20 0x0000000000415714 in main (argc=10, argv=0x7fffffffdc28)
    at /home/vries/gdb_versions/devel/src/gdb/gdb.c:32
...

Asserts because:
...
(gdb) 
#6  0x000000000074c828 in decode_line_full (location=0x2250080, flags=1,
search_pspace=0x0, default_symtab=0x0, default_line=0,
canonical=0x7fffffffd410, select_mode=0x0, filter=0x0) at
/home/vries/gdb_versions/devel/src/gdb/linespec.c:3233
3233      gdb_assert (result.size () == 1 || canonical->pre_expanded);
(gdb) p result
$1 = std::vector of length 0, capacity 0
(gdb) p canonical.pre_expanded
$2 = false
...

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Tentative patch:
...
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 4a634e3aff..6cbad6e40a 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3230,7 +3230,8 @@ decode_line_full (const struct event_location *locat
ion, int flags,
                                                                location);
   state = PARSER_STATE (&parser);

-  gdb_assert (result.size () == 1 || canonical->pre_expanded);
+  if (!(result.size () == 1 || canonical->pre_expanded))
+    throw_error (NOT_SUPPORTED_ERROR, "Location not available");
   canonical->pre_expanded = 1;

   /* Arrange for allocated canonical names to be freed.  */
...

Such that we get:
...
$ gdb a.out
Reading symbols from a.out...
(gdb) b main:L1
Location not available
(gdb) 
...

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
Message improved:
...
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 4a634e3aff..75ed8a9971 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3230,6 +3230,10 @@ decode_line_full (const struct event_location *loca
tion, int flags,
                                                                location);
   state = PARSER_STATE (&parser);

+  if (result.size () == 0)
+    throw_error (NOT_SUPPORTED_ERROR, _("Location %s not available"),
+                event_location_to_string ((struct event_location *)location))
;
+
   gdb_assert (result.size () == 1 || canonical->pre_expanded);
   canonical->pre_expanded = 1;
... 

Such that we have:
...
$ gdb a.out
Reading symbols from a.out...
(gdb) b main:L1
Location main:L1 not available
(gdb) 
...

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch submitted:
https://sourceware.org/pipermail/gdb-patches/2020-August/171516.html

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aldyh at redhat dot com

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
*** Bug 18140 has been marked as a duplicate of this bug. ***

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
Possible duplicate: PR25067, posted question to confirm.

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

--- Comment #8 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=626d23209fa3632561bb02ac11cb522bede91c1e

commit 626d23209fa3632561bb02ac11cb522bede91c1e
Author: Tom de Vries <tdevries@suse.de>
Date:   Fri Aug 28 12:02:20 2020 +0200

    [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.

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[Bug breakpoints/26544] linespec.c:3233: internal-error: void decode_line_full (): Assertion `result.size () == 1 || canonical->pre_expanded' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26544

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |10.1
             Status|NEW                         |RESOLVED

--- Comment #9 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch with test-case committed, marking resolved-fixed.

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