Compile error when turn on CONFIG_DEBUG

[cebarobot]

Description 描述

When turning on Testing and Debugging -> Enable debug features: instruction tracing and watchpoint (macro CONFIG_DEBUG ), compiling NEMU will get a format-truncation error:
开启 Testing and Debugging -> Enable debug features: instruction tracing and watchpoint （宏 CONFIG_DEBUG ）之后，编译 NEMU 会出现 format-truncation 报错:

include/common.h:34:39: error: ‘%s’ directive output may be truncated writing up to 79 bytes into a region of size 58 [-Werror=format-truncation=]

Full Error logs

ln -sf resource/softfloat/repo/build/Linux-x86_64-GCC/softfloat.a resource/softfloat/build/softfloat.a
In file included from include/common.h:26,
                 from include/cpu/cpu.h:19,
                 from src/cpu/cpu-exec.c:18:
src/cpu/cpu-exec.c: In function ‘fetch_decode’:
include/common.h:34:39: error: ‘%s’ directive output may be truncated writing up to 79 bytes into a region of size 58 [-Werror=format-truncation=]
   34 | #define FMT_WORD MUXDEF(CONFIG_ISA64, "0x%016lx", "0x%08x")
      |                                       ^~~~~~~~~~
include/macro.h:69:21: note: in definition of macro ‘__KEEP’
   69 | #define __KEEP(...) __VA_ARGS__
      |                     ^~~~~~~~~~~
src/cpu/cpu-exec.c:577:3: note: in expansion of macro ‘IFDEF’
  577 |   IFDEF(CONFIG_DEBUG,
      |   ^~~~~
include/macro.h:41:45: note: in expansion of macro ‘CHOOSE2nd’
   41 | #define MUX_WITH_COMMA(contain_comma, a, b) CHOOSE2nd(contain_comma a, b)
      |                                             ^~~~~~~~~
include/macro.h:42:44: note: in expansion of macro ‘MUX_WITH_COMMA’
   42 | #define MUX_MACRO_PROPERTY(p, macro, a, b) MUX_WITH_COMMA(concat(p, macro), a, b)
      |                                            ^~~~~~~~~~~~~~
include/macro.h:49:30: note: in expansion of macro ‘MUX_MACRO_PROPERTY’
   49 | #define MUXDEF(macro, X, Y)  MUX_MACRO_PROPERTY(__P_DEF_, macro, X, Y)
      |                              ^~~~~~~~~~~~~~~~~~
include/common.h:34:18: note: in expansion of macro ‘MUXDEF’
   34 | #define FMT_WORD MUXDEF(CONFIG_ISA64, "0x%016lx", "0x%08x")
      |                  ^~~~~~
src/cpu/cpu-exec.c:578:48: note: in expansion of macro ‘FMT_WORD’
  578 |         snprintf(s->logbuf, sizeof(s->logbuf), FMT_WORD ":   %s%*.s%s", s->pc,
      |                                                ^~~~~~~~
src/cpu/cpu-exec.c:578:62: note: format string is defined here
  578 |         snprintf(s->logbuf, sizeof(s->logbuf), FMT_WORD ":   %s%*.s%s", s->pc,
      |                                                              ^~
In file included from include/common.h:26,
                 from include/cpu/cpu.h:19,
                 from src/cpu/cpu-exec.c:18:
include/common.h:34:39: note: assuming directive output of 1 byte
   34 | #define FMT_WORD MUXDEF(CONFIG_ISA64, "0x%016lx", "0x%08x")
      |                                       ^~~~~~~~~~
include/macro.h:69:21: note: in definition of macro ‘__KEEP’
   69 | #define __KEEP(...) __VA_ARGS__
      |                     ^~~~~~~~~~~
src/cpu/cpu-exec.c:577:3: note: in expansion of macro ‘IFDEF’
  577 |   IFDEF(CONFIG_DEBUG,
      |   ^~~~~
include/macro.h:41:45: note: in expansion of macro ‘CHOOSE2nd’
   41 | #define MUX_WITH_COMMA(contain_comma, a, b) CHOOSE2nd(contain_comma a, b)
      |                                             ^~~~~~~~~
include/macro.h:42:44: note: in expansion of macro ‘MUX_WITH_COMMA’
   42 | #define MUX_MACRO_PROPERTY(p, macro, a, b) MUX_WITH_COMMA(concat(p, macro), a, b)
      |                                            ^~~~~~~~~~~~~~
include/macro.h:49:30: note: in expansion of macro ‘MUX_MACRO_PROPERTY’
   49 | #define MUXDEF(macro, X, Y)  MUX_MACRO_PROPERTY(__P_DEF_, macro, X, Y)
      |                              ^~~~~~~~~~~~~~~~~~
include/common.h:34:18: note: in expansion of macro ‘MUXDEF’
   34 | #define FMT_WORD MUXDEF(CONFIG_ISA64, "0x%016lx", "0x%08x")
      |                  ^~~~~~
src/cpu/cpu-exec.c:578:48: note: in expansion of macro ‘FMT_WORD’
  578 |         snprintf(s->logbuf, sizeof(s->logbuf), FMT_WORD ":   %s%*.s%s", s->pc,
      |                                                ^~~~~~~~
In file included from /usr/include/stdio.h:867,
                 from include/debug.h:20,
                 from include/common.h:55,
                 from include/cpu/cpu.h:19,
                 from src/cpu/cpu-exec.c:18:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:67:10: note: ‘__builtin___snprintf_chk’ output between 23 and 2147483828 bytes into a destination of size 80
   67 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   68 |        __bos (__s), __fmt, __va_arg_pack ());
      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Environment 环境

• gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
• commit 5e081a5

Possible solutions 可能的解决方案

I think this warning is a misreport. This debug output may be truncated in theroy, not not in practice. I think add -Wno-format-truncation to CFLAGS and CXXFLAGS in Makefile will solve this. I can't think of any unexpected results.
我认为这个警告是误报。这个调试输出理论上可能被截断，但实际并不会（实际上就算节段了也完全不影响）。在Makefile中的 CFLAGS 和 CXXFLAGS 中添加 -Wno-format-truncation 可以解决此问题。我想不出有什么出乎意料的结果。