Filtering shadowed variables in info local

["Sargsyan, Eduard" <eduard.sargsyan@intel.com>]

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Hi,

After https://sourceware.org/pipermail/gdb-patches/2021-June/180478.html
and https://sourceware.org/pipermail/gdb-patches/2022-January/184819.html
GDB prints "<shadowed: decl at line 5>" if variable has been marked as shadowed.
But user might not be interested in seeing any shadowed variables.

For example, this code:

     1 int num = 1;
     2 int
     3 main ()
     4  {
     5    const char *str = "main";
     6    int num = 3;
     7    {
     8       const char *str = "nested";
     9       int num = 5;
    10      num = 0; //  break here
    11    }
    12    return num;
    13  }

Brings GDB to (when stopped at line 10):

  (gdb) info locals
  str = 0x555555556009 "nested"
  num = 5
  str = 0x555555556004 "main"     <shadowed: decl at line 5>
  num = 3 <shadowed: decl at line 6>

Prints both shadowed and local variables "str" and "num", but does not print
global accessible variable "num".

  (gdb) print num
  $1 = 5
  (gdb) print ::num
  $2 = 1

Setting value to local variable "num" works as expected:
  (gdb) set num = 7
  (gdb) info locals
  str = 0x555555556009 "nested"
  num = 7
  str = 0x555555556004 "main"     <shadowed: decl at line 5>
  num = 3 <shadowed: decl at line 6>

In C++ shadowed variable is not accessible, to there is no way to change value
of variable "num" declared at line 5.  So only local and global variables can
be modified:

  (gdb) set ::num = 9
  (gdb) print num
  $3 = 7
  (gdb) print ::num
  $4 = 9

I'm not sure if printing shadowed variables "num" and "str" are useful in the
use case described above.  Maybe adding a setting to filter out shadowed
variables makes sense (by default the setting will be disabled).

Example:

  (gdb) info locals
  str = 0x555555556009 "nested"
  num = 7
  str = 0x555555556004 "main"     <shadowed: decl at line 5>
  num = 3 <shadowed: decl at line 6>
  (gdb) set print shadowed off
  (gdb) info locals
  str = 0x555555556009 "nested"
  num = 7
  (gdb) set print shadowed on
  (gdb) info locals
  str = 0x555555556009 "nested"
  num = 7
  str = 0x555555556004 "main"     <shadowed: decl at line 5>
  num = 3 <shadowed: decl at line 6>

What are your thoughts?

- Eduard

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