C - 编译程序时出现多个警告"pointer is missing a nullability type specifier"，我该怎么办？

Question

我最近开始在编译 C 程序时遇到问题，从 stdio.h 或 [ 等不同的 C 程序包收到 10、20 或 100 条警告=51=]。

警告有些不同，但通常是这样说的：

/usr/local/include/_stdio.h:93:16: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or
      _Null_unspecified) [-Wnullability-completeness]
        unsigned char   *_base;

我的程序仍然可以编译并运行良好，但我担心这需要修复，而且在终端中收到所有这些警告也非常烦人。

我几乎可以肯定这些警告是在我将系统更新到 macOS Catalina 后开始显示的，但我不知道从哪里开始解决它。

更具体地说，当我像这样编译一个简单的helloworld.c程序时

#include <stdio.h>

int main (void) {
    printf("Hello World!"); 
    return 0; 
}

使用以下命令：

make helloworld

或

gcc helloworld.c -o helloworld

..我收到以下警告，即使程序实际编译。

In file included from helloworld.c:1:
In file included from /usr/local/include/stdio.h:64:
/usr/local/include/_stdio.h:93:16: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        unsigned char   *_base;
                        ^
/usr/local/include/_stdio.h:93:16: note: insert '_Nullable' if the pointer may be null
        unsigned char   *_base;
                        ^
                          _Nullable 
/usr/local/include/_stdio.h:93:16: note: insert '_Nonnull' if the pointer should never be null
        unsigned char   *_base;
                        ^
                          _Nonnull 
/usr/local/include/_stdio.h:138:32: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        int     (* _Nullable _read) (void *, char *, int);
                                          ^
/usr/local/include/_stdio.h:138:32: note: insert '_Nullable' if the pointer may be null
        int     (* _Nullable _read) (void *, char *, int);
                                          ^
                                           _Nullable
/usr/local/include/_stdio.h:138:32: note: insert '_Nonnull' if the pointer should never be null
        int     (* _Nullable _read) (void *, char *, int);
                                          ^
                                           _Nonnull
/usr/local/include/_stdio.h:138:40: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        int     (* _Nullable _read) (void *, char *, int);
                                                  ^
/usr/local/include/_stdio.h:138:40: note: insert '_Nullable' if the pointer may be null
        int     (* _Nullable _read) (void *, char *, int);
                                                  ^
                                                   _Nullable
/usr/local/include/_stdio.h:138:40: note: insert '_Nonnull' if the pointer should never be null
        int     (* _Nullable _read) (void *, char *, int);
                                                  ^
                                                   _Nonnull
/usr/local/include/_stdio.h:139:35: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        fpos_t  (* _Nullable _seek) (void *, fpos_t, int);
                                          ^
/usr/local/include/_stdio.h:139:35: note: insert '_Nullable' if the pointer may be null
        fpos_t  (* _Nullable _seek) (void *, fpos_t, int);
                                          ^
                                           _Nullable
/usr/local/include/_stdio.h:139:35: note: insert '_Nonnull' if the pointer should never be null
        fpos_t  (* _Nullable _seek) (void *, fpos_t, int);
                                          ^
                                           _Nonnull
/usr/local/include/_stdio.h:140:32: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        int     (* _Nullable _write)(void *, const char *, int);
                                          ^
/usr/local/include/_stdio.h:140:32: note: insert '_Nullable' if the pointer may be null
        int     (* _Nullable _write)(void *, const char *, int);
                                          ^
                                           _Nullable
/usr/local/include/_stdio.h:140:32: note: insert '_Nonnull' if the pointer should never be null
        int     (* _Nullable _write)(void *, const char *, int);
                                          ^
                                           _Nonnull
/usr/local/include/_stdio.h:140:46: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        int     (* _Nullable _write)(void *, const char *, int);
                                                        ^
/usr/local/include/_stdio.h:140:46: note: insert '_Nullable' if the pointer may be null
        int     (* _Nullable _write)(void *, const char *, int);
                                                        ^
                                                         _Nullable
/usr/local/include/_stdio.h:140:46: note: insert '_Nonnull' if the pointer should never be null
        int     (* _Nullable _write)(void *, const char *, int);
                                                        ^
                                                         _Nonnull
/usr/local/include/_stdio.h:144:18: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
        struct __sFILEX *_extra; /* additions to FILE to not break ABI */
                        ^
/usr/local/include/_stdio.h:144:18: note: insert '_Nullable' if the pointer may be null
        struct __sFILEX *_extra; /* additions to FILE to not break ABI */
                        ^
                          _Nullable 
/usr/local/include/_stdio.h:144:18: note: insert '_Nonnull' if the pointer should never be null
        struct __sFILEX *_extra; /* additions to FILE to not break ABI */
                        ^
                          _Nonnull 
In file included from helloworld.c:1:
/usr/local/include/stdio.h:67:13: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
extern FILE *__stdinp;
            ^
/usr/local/include/stdio.h:67:13: note: insert '_Nullable' if the pointer may be null
extern FILE *__stdinp;
            ^
              _Nullable 
/usr/local/include/stdio.h:67:13: note: insert '_Nonnull' if the pointer should never be null
extern FILE *__stdinp;
            ^
              _Nonnull 
/usr/local/include/stdio.h:386:41: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
                 int (* _Nullable)(void *, const char *, int),
                                        ^
/usr/local/include/stdio.h:386:41: note: insert '_Nullable' if the pointer may be null
                 int (* _Nullable)(void *, const char *, int),
                                        ^
                                         _Nullable
/usr/local/include/stdio.h:386:41: note: insert '_Nonnull' if the pointer should never be null
                 int (* _Nullable)(void *, const char *, int),
                                        ^
                                         _Nonnull
/usr/local/include/stdio.h:386:55: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
                 int (* _Nullable)(void *, const char *, int),
                                                      ^
/usr/local/include/stdio.h:386:55: note: insert '_Nullable' if the pointer may be null
                 int (* _Nullable)(void *, const char *, int),
                                                      ^
                                                       _Nullable
/usr/local/include/stdio.h:386:55: note: insert '_Nonnull' if the pointer should never be null
                 int (* _Nullable)(void *, const char *, int),
                                                      ^
                                                       _Nonnull
/usr/local/include/stdio.h:387:44: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
                 fpos_t (* _Nullable)(void *, fpos_t, int),
                                           ^
/usr/local/include/stdio.h:387:44: note: insert '_Nullable' if the pointer may be null
                 fpos_t (* _Nullable)(void *, fpos_t, int),
                                           ^
                                            _Nullable
/usr/local/include/stdio.h:387:44: note: insert '_Nonnull' if the pointer should never be null
                 fpos_t (* _Nullable)(void *, fpos_t, int),
                                           ^
                                            _Nonnull
/usr/local/include/stdio.h:388:41: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
                 int (* _Nullable)(void *));
                                        ^
/usr/local/include/stdio.h:388:41: note: insert '_Nullable' if the pointer may be null
                 int (* _Nullable)(void *));
                                        ^
                                         _Nullable
/usr/local/include/stdio.h:388:41: note: insert '_Nonnull' if the pointer should never be null
                 int (* _Nullable)(void *));
                                        ^
                                         _Nonnull
/usr/local/include/stdio.h:384:6: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
FILE    *funopen(const void *,
        ^
/usr/local/include/stdio.h:384:6: note: insert '_Nullable' if the pointer may be null
FILE    *funopen(const void *,
        ^
          _Nullable 
/usr/local/include/stdio.h:384:6: note: insert '_Nonnull' if the pointer should never be null
FILE    *funopen(const void *,
        ^
          _Nonnull 
13 warnings generated.

编辑：Mike Minaev 提供了我现在正在使用的临时修复程序。命令：

gcc -Wno-nullability-completeness helloworld.c -o helloworld

编辑：我环顾四周并尝试了 or 的各种解决方案，包括使用 CLI 重新安装 xcode 但没有结果。

下面的

Jonathan Leffler 推测这可能是因为我的头文件位于 usr/local/include 而不是 usr/include 但没有建议修复。

Answer 1

我的临时快速修复：

gcc -Wno-nullability-completeness file.c

C - 编译程序时出现多个警告"pointer is missing a nullability type specifier"，我该怎么办？

C - multiple warnings "pointer is missing a nullability type specifier" when compiling program, what do I do?

c

macos

stdio

clang

macos-catalina