lldb should print a notice when `source list` paging reaches the end of the file

[Guo-yyds]

ubuntu 20.04
clang 18.1.8
lldb 18.1.8

This is the c source code.

#include<stdio.h>
int main()
{
    printf("Hello World\n");
    return 0;
}

I use the compile

clang -g -O0 test.c

then, lldb list is not working

[llvmbot]

@llvm/issue-subscribers-lldb

Author: 郭浩男 (Guo-yyds)

ubuntu 20.04 clang 18.1.8 lldb 18.1.8

This is the c source code.

#include<stdio.h>
int main()
{
    printf("Hello World\n");
    return 0;
}

I use the compile

clang -g -O0 test.c

then, lldb list is not working

[DavidSpickett]

Thanks for the report, reproduces with the latest build (e89cd50).

(lldb) help list
List relevant source code using one of several shorthand formats.  Expects 'raw' input (see
'help raw-input'.)

Syntax:
_regexp-list <file>:<line>   // List around specific file/line
_regexp-list <line>          // List current file around specified line
_regexp-list <function-name> // List specified function
_regexp-list 0x<address>     // List around specified address
_regexp-list -[<count>]      // List previous <count> lines
_regexp-list                 // List subsequent lines

'list' is an abbreviation for '_regexp-list'

So this should "List subsequent lines".

I don't see any tests for it, but it's hard to search for. I'll find out for sure tomorrow.

[jimingham]

list without arguments continues paging from the previous "list" request. Since you've reached the end of the file, there's nothing more to page.

So this is the expected behavior, but we could make it clearer by printing or something like that.

[Guo-yyds]

Ok
I got it.
lldb list is not same with gdb

[DavidSpickett]

GDB's list looks the same:

(gdb) help list
list, l
List specified function or line.
With no argument, lists ten more lines after or around previous listing.
"list -" lists the ten lines before a previous ten-line listing.
One argument specifies a line, and ten lines are listed around that line.
Two arguments with comma between specify starting and ending lines to list.
Lines can be specified in these ways:
  LINENUM, to list around that line in current file,
  FILE:LINENUM, to list around that line in that file,
  FUNCTION, to list around beginning of that function,
  FILE:FUNCTION, to distinguish among like-named static functions.
  *ADDRESS, to list around the line containing that address.
With two args, if one is empty, it stands for ten lines away from
the other arg.

By default, when a single location is given, display ten lines.
This can be changed using "set listsize", and the current value
can be shown using "show listsize".

However when there is no "previous listing" it defaults, I think, to ten lines around the current line:

$ gdb /tmp/test.o
<...>
(gdb) b main
Breakpoint 1 at 0x76c: file /tmp/test.c, line 4.
(gdb) r
Starting program: /tmp/test.o
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/aarch64-linux-gnu/libthread_db.so.1".

Breakpoint 1, main () at /tmp/test.c:4
4           printf("Hello World\n");
(gdb) list
1       #include<stdio.h>
2       int main()
3       {
4           printf("Hello World\n");
5           return 0;
6       }

We don't do that:

$ ./bin/lldb /tmp/test.o
(lldb) target create "/tmp/test.o"
Current executable set to '/tmp/test.o' (aarch64).
(lldb) b main
Breakpoint 1: where = test.o`main + 24 at test.c:4:5, address = 0x000000000000076c
(lldb) r
Process 270701 launched: '/tmp/test.o' (aarch64)
Process 270701 stopped
* thread #1, name = 'test.o', stop reason = breakpoint 1.1
    frame #0: 0x0000aaaaaaaaa76c test.o`main at test.c:4:5
   1    #include<stdio.h>
   2    int main()
   3    {
-> 4        printf("Hello World\n");
   5        return 0;
   6    }
(lldb) list
(lldb)

So I agree at least we should say something here. Defaulting to the current location seems useful too.