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c - 进行条件编译时出错

问题描述

[在此处输入链接描述][1]我正在编写这个程序，它将启用条件编译。

当程序以这样的标准方式编译时，它可以正常工作而没有任何错误消息：

gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack

但是当我想用条件编译进行编译时，我收到一条错误消息，说在 display.c 中有我的函数的隐式声明

这是我如何编译它：

gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK

这是我在代码中编写条件命令的方式：

#ifdef STACK
printLinkedList( stack );
#endif

这是stack.h显示包含的文件，LinkedList.h其中包含的函数原型为printLinkedList.

#ifndef STACK
#define STACK

#include "LinkedList.h"

LinkedList *createStack();
void push( LinkedList *, void * );
void *top( LinkedList * );
void *pop( LinkedList * );
void freeStack( LinkedList * );

#endif

我可以知道这里有什么问题吗？我似乎找不到问题，因为第一个语句运行良好，但是当我添加“-D STACK”时，程序只显示错误消息。我的编译命令有问题吗？

我收到的错误消息：

display.c: In function ‘display’:
display.c:21:5: error: unknown type name ‘LinkedList’
   21 |     LinkedList *stack = NULL;
      |     ^~~~~~~~~~
display.c:22:13: error: implicit declaration of function ‘createStack’ [-Werror=implicit-function-declaration]
   22 |     stack = createStack();
      |             ^~~~~~~~~~~
display.c:22:11: error: assignment to ‘int *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   22 |     stack = createStack();
      |           ^
display.c:47:21: error: implicit declaration of function ‘push’ [-Werror=implicit-function-declaration]
   47 |                     push( stack, bracket );
      |                     ^~~~
display.c:52:30: error: request for member ‘head’ in something not a structure or union
   52 |                     if( stack->head != NULL )
      |                              ^~
display.c:54:38: error: implicit declaration of function ‘top’ [-Werror=implicit-function-declaration]
   54 |                         popBracket = top( stack );
      |                                      ^~~
display.c:54:36: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   54 |                         popBracket = top( stack );
      |                                    ^
display.c:72:42: error: implicit declaration of function ‘pop’ [-Werror=implicit-function-declaration]
   72 |                             popBracket = pop( stack );
      |                                          ^~~
display.c:72:40: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   72 |                             popBracket = pop( stack );
      |                                        ^
display.c:108:17: error: implicit declaration of function ‘printLinkedList’ [-Werror=implicit-function-declaration]
  108 |                 printLinkedList( stack );
      |                 ^~~~~~~~~~~~~~~
display.c:147:22: error: request for member ‘head’ in something not a structure or union
  147 |             if( stack->head == NULL )   /* Good case */
      |                      ^~
display.c:151:28: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
  151 |                 popBracket = top( stack );
      |                            ^
display.c:164:5: error: implicit declaration of function ‘freeStack’ [-Werror=implicit-function-declaration]
  164 |     freeStack( stack );
      |     ^~~~~~~~~
cc1: all warnings being treated as errors
calmen@calmen:~/Desktop/Project/BracketCheck$ vim display.h
calmen@calmen:~/Desktop/Project/BracketCheck$ gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK
display.c: In function ‘display’:
display.c:21:5: error: unknown type name ‘LinkedList’
   21 |     LinkedList *stack = NULL;
      |     ^~~~~~~~~~
display.c:22:13: error: implicit declaration of function ‘createStack’ [-Werror=implicit-function-declaration]
   22 |     stack = createStack();
      |             ^~~~~~~~~~~
display.c:22:11: error: assignment to ‘int *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   22 |     stack = createStack();
      |           ^
display.c:47:21: error: implicit declaration of function ‘push’ [-Werror=implicit-function-declaration]
   47 |                     push( stack, bracket );
      |                     ^~~~
display.c:52:30: error: request for member ‘head’ in something not a structure or union
   52 |                     if( stack->head != NULL )
      |                              ^~
display.c:54:38: error: implicit declaration of function ‘top’ [-Werror=implicit-function-declaration]
   54 |                         popBracket = top( stack );
      |                                      ^~~
display.c:54:36: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   54 |                         popBracket = top( stack );
      |                                    ^
display.c:72:42: error: implicit declaration of function ‘pop’ [-Werror=implicit-function-declaration]
   72 |                             popBracket = pop( stack );
      |                                          ^~~
display.c:72:40: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
   72 |                             popBracket = pop( stack );
      |                                        ^
display.c:108:17: error: implicit declaration of function ‘printLinkedList’ [-Werror=implicit-function-declaration]
  108 |                 printLinkedList( stack );
      |                 ^~~~~~~~~~~~~~~
display.c:147:22: error: request for member ‘head’ in something not a structure or union
  147 |             if( stack->head == NULL )   /* Good case */
      |                      ^~
display.c:151:28: error: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
  151 |                 popBracket = top( stack );
      |                            ^
display.c:164:5: error: implicit declaration of function ‘freeStack’ [-Werror=implicit-function-declaration]
  164 |     freeStack( stack );
      |     ^~~~~~~~~
cc1: all warnings being treated as errors

这些文件可以在此处的文件夹中找到。[1]：https ://github.com/Calmen00-code/BracketCheck

标签： cconditional-compilationmakefile

解决方案

gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK

很奇怪。我会删除和之间的-D空间STACK

您可能会对添加-Wextra -fanalyze到您的gcc命令感兴趣。阅读关于调用 GCC的章节，关于静态分析器选项的部分，并在 2020 年底考虑升级到GCC 10。

此外，-ansi指的是旧的 C 标准。阅读n1570和Modern C然后考虑使用-std=c11

编译您的代码BracketCheck.tar.gz（的 md5sum 1b81b34f26db85fef69bda62a5bd4e63）时，make CFLAGS='-Wall -Wextra -g -std=c11'我得到：

 display.c: In function ‘display’:
 display.c:21:5: error: unknown type name ‘LinkedList’
    21 |     LinkedList *stack = NULL;
       |     ^~~~~~~~~~
 display.c:22:13: warning: implicit declaration of function ‘createStack’ [-Wimplicit-function-declaration]
    22 |     stack = createStack();
       |             ^~~~~~~~~~~
 display.c:22:11: warning: assignment to ‘int *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
    22 |     stack = createStack();
       |           ^
 display.c:47:21: warning: implicit declaration of function ‘push’ [-Wimplicit-function-declaration]
    47 |                     push( stack, bracket );
       |                     ^~~~
 display.c:52:30: error: request for member ‘head’ in something not a structure or union
    52 |                     if( stack->head != NULL )
       |                              ^~
 display.c:54:38: warning: implicit declaration of function ‘top’ [-Wimplicit-function-declaration]
    54 |                         popBracket = top( stack );
       |                                      ^~~
 display.c:54:36: warning: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
    54 |                         popBracket = top( stack );
       |                                    ^
 display.c:72:42: warning: implicit declaration of function ‘pop’ [-Wimplicit-function-declaration]
    72 |                             popBracket = pop( stack );
       |                                          ^~~
 display.c:72:40: warning: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
    72 |                             popBracket = pop( stack );
       |                                        ^
 display.c:108:17: warning: implicit declaration of function ‘printLinkedList’ [-Wimplicit-function-declaration]
   108 |                 printLinkedList( stack );
       |                 ^~~~~~~~~~~~~~~
 display.c:147:22: error: request for member ‘head’ in something not a structure or union
   147 |             if( stack->head == NULL )   /* Good case */
       |                      ^~
 display.c:151:28: warning: assignment to ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   151 |                 popBracket = top( stack );
       |                            ^
 display.c:164:5: warning: implicit declaration of function ‘freeStack’ [-Wimplicit-function-declaration]
   164 |     freeStack( stack );

这是在带有GCC 10.2的 Linux/x86-64/Ubuntu 20.04 上。

我建议您修复您的代码，直到您完全没有收到任何警告。

添加-DSTACK并不能修复所有错误。一旦它们都固定了，使用GDB来了解程序的行为。

您可能会对这份报告草稿以及资助它的解码器和战车项目感兴趣。

您也可以尝试在您的代码Frama-C或Clang 静态分析器上使用。注意赖斯定理。

在阅读Dragon book之后，您可能会考虑使用GNU autoconf和/或GNU bison和/或ANTLR和/或GPP使用元编程技术生成一些代码（在 C 中，或您的makefile...）。

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