即使使用-g3或-ggdb3或-gdwarf-4,gdb宏符号也不存在

Question

我有这个C文件(sample.c):

#include <stdio.h>
#define M 42
#define ADD(x) (M + x)
int main ()
{
  printf("%d\n", M);
  printf("%d\n", ADD(2));
  return 0;
}

我编译的是:

$ gcc -O0 -Wall -g3 sample.c -o sample

然后调试

$ gdb ./sample
GNU gdb (Gentoo 7.3.1 p2) 7.3.1
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.gentoo.org/>...
Reading symbols from /tmp/sample...done.
(gdb) macro list
(gdb) macro expand ADD(2)
expands to: ADD(2)
(gdb) print M
No symbol "M" in current context.
(gdb) q

这曾经工作过.我需要这个才能工作,因为我正在使用#define硬件外设和内存地址名称的库.

这似乎与Sourceware gdb站点上显示的行为直接矛盾.

我究竟做错了什么？

Answer 1

看起来宏需要以这种或那种方式"引入范围".如果您完全按照链接到的页面中的示例,它们就像宣传的那样工作(至少它们对我有用).

示例(t.c是您的源文件):

$ gcc -O0 -g3 t.c
$ gdb ./a.out 
GNU gdb (Gentoo 7.3.1 p2) 7.3.1
...
Reading symbols from .../a.out...done.
(gdb) info macro ADD
The symbol `ADD' has no definition as a C/C++ preprocessor macro
at <user-defined>:-1
             // Macros not loaded yet
(gdb) list main
1   #include <stdio.h>
2   #define M 42
3   #define ADD(x) (M + x)
4   int main ()
5   {
6     printf("%d\n", M);
7     printf("%d\n", ADD(2));
8     return 0;
9   }
(gdb) info macro ADD
Defined at /home/foo/tmp/t.c:3
#define ADD(x) (M + x)
             // Macros "in scope"/loaded
(gdb) macro expand ADD(42)
expands to: (42 + 42)
(gdb) macro expand M      
expands to: 42
(gdb) macro expand ADD(M)
expands to: (42 + 42)
(gdb) 

要么:

$ gdb ./a.out 
GNU gdb (Gentoo 7.3.1 p2) 7.3.1
...
Reading symbols from .../a.out...done.
(gdb) macro expand ADD(1)
expands to: ADD(1)
             // Macros not available yet
(gdb) break main
Breakpoint 1 at 0x400538: file t.c, line 6.
(gdb) r
Starting program: /home/foo/tmp/a.out 
Breakpoint 1, main () at t.c:6
6     printf("%d\n", M);
(gdb) macro expand ADD(1)
expands to: (42 + 1)
             // Macros loaded
(gdb)