进行条件编译时出错
Error while making conditional compilation
[在此处输入 link 描述][1]我正在编写此程序，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，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，我有一条错误消息说我的函数在 display.c
中有隐式声明
以下是我的编译方式：
gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK
下面是我在代码中编写条件命令的方式：
#ifdef STACK
printLinkedList( stack );
#endif
这里是 stack.h 文件，显示了 LinkedList.h 的包含，它具有 printLinkedList.
的函数原型
#ifndef STACK
#define STACK
#include "LinkedList.h"
LinkedList *createStack();
void push( LinkedList *, void * );
void *top( LinkedList * );
void *pop( LinkedList * );
void freeStack( LinkedList * );
#endif
请问这里有什么问题吗？我似乎找不到问题，因为第一条语句运行良好，但是当我添加“-D STACK”时，程序只显示错误消息。是不是我的编译命令有问题？
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
文件可以在此处的文件夹中找到。
[1]: https://github.com/Calmen00-code/BracketCheck
gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK
很奇怪。我会删除 -D 和 STACK
之间的 space
您可能会对在 gcc 命令中添加 -Wextra -fanalyze 感兴趣。阅读有关 invoking GCC, section about static analyzer options, and in end of 2020 consider upgrading to GCC 10.
的章节
此外，-ansi 指的是旧的 C 标准。阅读 n1570 and Modern C 然后考虑使用 -std=c11
当使用 make CFLAGS='-Wall -Wextra -g -std=c11' 编译代码 BracketCheck.tar.gz（md5sum 1b81b34f26db85fef69bda62a5bd4e63）时，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 Linux/x86-64/Ubuntu 20.04 上 GCC 10.2。
我建议修复你的代码，直到你完全没有收到警告。
添加 -DSTACK 并不能修复所有错误。一旦它们全部修复，请使用 GDB 了解您的程序的行为。
您可能会对 this draft report and the DECODER and CHARIOT 个资助它的项目感兴趣。
您也可以尝试在您的代码上使用 Frama-C or the Clang static analyzer. Be aware of Rice's theorem。
您可以考虑使用 GNU autoconf and/or GNU bison and/or ANTLR and/or GPP to generate some of your code (in C, or your makefile ...) using meta-programming techniques after reading the Dragon book。
问题是 stack.h 文件中的 include guard:
#ifndef STACK
当您随后在命令行上定义 STACK 时，条件变为 FALSE，并且不包括 header 内容。这会导致 C 文件中缺少原型。
要解决此问题，您需要更改 C 文件或 header 文件以使用不同的预处理器变量。
[在此处输入 link 描述][1]我正在编写此程序，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，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，我有一条错误消息说我的函数在 display.c
中有隐式声明以下是我的编译方式：
gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK
下面是我在代码中编写条件命令的方式：
#ifdef STACK
printLinkedList( stack );
#endif
这里是 stack.h 文件，显示了 LinkedList.h 的包含，它具有 printLinkedList.
#ifndef STACK
#define STACK
#include "LinkedList.h"
LinkedList *createStack();
void push( LinkedList *, void * );
void *top( LinkedList * );
void *pop( LinkedList * );
void freeStack( LinkedList * );
#endif
请问这里有什么问题吗？我似乎找不到问题，因为第一条语句运行良好，但是当我添加“-D STACK”时，程序只显示错误消息。是不是我的编译命令有问题？
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
文件可以在此处的文件夹中找到。 [1]: https://github.com/Calmen00-code/BracketCheck
gcc -Werror -Wall -pedantic -ansi -g -c display.c -o displayStack -D STACK
很奇怪。我会删除 -D 和 STACK
您可能会对在 gcc 命令中添加 -Wextra -fanalyze 感兴趣。阅读有关 invoking GCC, section about static analyzer options, and in end of 2020 consider upgrading to GCC 10.
此外，-ansi 指的是旧的 C 标准。阅读 n1570 and Modern C 然后考虑使用 -std=c11
当使用 make CFLAGS='-Wall -Wextra -g -std=c11' 编译代码 BracketCheck.tar.gz（md5sum 1b81b34f26db85fef69bda62a5bd4e63）时，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 Linux/x86-64/Ubuntu 20.04 上 GCC 10.2。
我建议修复你的代码，直到你完全没有收到警告。
添加 -DSTACK 并不能修复所有错误。一旦它们全部修复，请使用 GDB 了解您的程序的行为。
您可能会对 this draft report and the DECODER and CHARIOT 个资助它的项目感兴趣。
您也可以尝试在您的代码上使用 Frama-C or the Clang static analyzer. Be aware of Rice's theorem。
您可以考虑使用 GNU autoconf and/or GNU bison and/or ANTLR and/or GPP to generate some of your code (in C, or your makefile ...) using meta-programming techniques after reading the Dragon book。
问题是 stack.h 文件中的 include guard:
#ifndef STACK
当您随后在命令行上定义 STACK 时，条件变为 FALSE，并且不包括 header 内容。这会导致 C 文件中缺少原型。
要解决此问题，您需要更改 C 文件或 header 文件以使用不同的预处理器变量。