[PING][PATCH] [gdb/exp] Fix ns var lookup when stopped at inlined fn call

[Tom de Vries <tdevries@suse.de>]

On 6/4/26 1:19 PM, Tom de Vries wrote:
> Consider test.c:
> ...
>       1	namespace mod_a {
>       2	  int xxx = 10;
>       3	}
>       4
>       5	static inline int __attribute__((always_inline))
>       6	inlined () {
>       7	  return 0;
>       8	}
>       9
>      10	int main () {
>      11	  using namespace mod_a;
>      12	  int res = inlined ();
>      13	  return res + xxx;
>      14	}
> ...
> compiled with "g++ test.c -g".
> 
> Trying to print variable xxx at line 12 fails:
> ...
> $ gdb -q -batch a.out -ex start -ex "p xxx"
>    ...
> Temporary breakpoint 1, main () at test.c:12
> 12	  int res = inlined ();
> No symbol "xxx" in current context.
> ...
> 
> The problem is here in function using_direct::valid_line:
> ...
>        CORE_ADDR curr_pc = get_frame_pc (get_selected_frame (nullptr));
>        symtab_and_line curr_sal = find_sal_for_pc (curr_pc, 0);
>        return (decl_line <= curr_sal.line)
> 	     || (decl_line >= boundary);
> ...
> where we're trying to decide whether "using namespace mod_a" is applicable.
> 
> The decl_line is 11, as expected.
> 
> If curr_sal.line were 12, decl_line <= curr_sal.line would be true, and
> using_direct::valid_line would return true.
> 
> But instead, curr_sal.line is 7.
> 
> This is sort of correct, the current PC maps to that line.  It's just that gdb
> steps into inlined functions in two steps, each with identical PC:
> - once stopping at the call site (line 12 in this case)
> - once stopping at the PC line (line 7 in this case)
> 
> The function using_direct::valid_line doesn't apply this logic, and
> consequently line 7 is used for both cases.
> 
> Fix this by using find_frame_sal instead.
> 

Ping.

Thanks,
- Tom

> Tested on x86_64-linux.
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34201
> ---
>   gdb/namespace.c                     |  4 +--
>   gdb/testsuite/gdb.cp/ns-inlined.c   | 41 +++++++++++++++++++++++
>   gdb/testsuite/gdb.cp/ns-inlined.exp | 52 +++++++++++++++++++++++++++++
>   3 files changed, 95 insertions(+), 2 deletions(-)
>   create mode 100644 gdb/testsuite/gdb.cp/ns-inlined.c
>   create mode 100644 gdb/testsuite/gdb.cp/ns-inlined.exp
> 
> diff --git a/gdb/namespace.c b/gdb/namespace.c
> index 5b5749369ee..fec5e5cf67d 100644
> --- a/gdb/namespace.c
> +++ b/gdb/namespace.c
> @@ -111,8 +111,8 @@ using_direct::valid_line (unsigned int boundary) const
>   {
>     try
>       {
> -      CORE_ADDR curr_pc = get_frame_pc (get_selected_frame (nullptr));
> -      symtab_and_line curr_sal = find_sal_for_pc (curr_pc, 0);
> +      frame_info_ptr frame = get_selected_frame ();
> +      symtab_and_line curr_sal = find_frame_sal (frame);
>         return (decl_line <= curr_sal.line)
>   	     || (decl_line >= boundary);
>       }
> diff --git a/gdb/testsuite/gdb.cp/ns-inlined.c b/gdb/testsuite/gdb.cp/ns-inlined.c
> new file mode 100644
> index 00000000000..26e72f6ba3f
> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/ns-inlined.c
> @@ -0,0 +1,41 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2026 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/>.  */
> +
> +namespace mod_a
> +{
> +  int xxx = 10;
> +}
> +
> +static inline int __attribute__((always_inline))
> +inlined ()
> +{
> +  return 0;
> +}
> +
> +static void
> +foo ()
> +{
> +}
> +
> +int
> +main ()
> +{
> +  foo ();                   /* stop 1.  */
> +  using namespace mod_a;
> +  int res = inlined ();     /* stop 2.  */
> +  return res + xxx;         /* stop 3.  */
> +}
> diff --git a/gdb/testsuite/gdb.cp/ns-inlined.exp b/gdb/testsuite/gdb.cp/ns-inlined.exp
> new file mode 100644
> index 00000000000..90cfbc0ff23
> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/ns-inlined.exp
> @@ -0,0 +1,52 @@
> +# Copyright 2026 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 .c
> +
> +set stop2_line [gdb_get_line_number "stop 2"]
> +set stop3_line [gdb_get_line_number "stop 3"]
> +
> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
> +	 {debug c++}]} {
> +    return
> +}
> +
> +if {![runto_main]} {
> +    return
> +}
> +
> +with_test_prefix "stop 1" {
> +    gdb_test "print xxx" \
> +	[string_to_regexp {No symbol "xxx" in current context.}]
> +}
> +
> +gdb_test "next" \
> +    "\r\n$stop2_line\t\[^\r\n\]+" \
> +    "next to stop 2"
> +
> +with_test_prefix "stop 2" {
> +    # Regression test for PR exp/34201.
> +    gdb_test "print xxx" \
> +	"$valnum_re = 10"
> +}
> +
> +gdb_test "next" \
> +    "\r\n$stop3_line\t\[^\r\n\]+" \
> +    "next to stop 3"
> +
> +with_test_prefix "stop 3" {
> +    gdb_test "print xxx" \
> +	"$valnum_re = 10"
> +}
> 
> base-commit: 48997323b0f929d3255a4845f8a3800c6c00a53a