解决 error: implicit declaration o

今天在安装zat软件的时候遇到问题ruby运行环境中的thin_parser扩展库报错的问题，错误信息如下：

Building native extensions. This could take a while...
ERROR:  Error installing zendesk_apps_tools:
    ERROR: Failed to build gem native extension.

    current directory: /Library/Ruby/Gems/2.6.0/gems/thin-1.7.2/ext/thin_parser
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r ./siteconf20201021-92246-lmkt32.rb extconf.rb
checking for main() in -lc... yes
creating Makefile

current directory: /Library/Ruby/Gems/2.6.0/gems/thin-1.7.2/ext/thin_parser
make "DESTDIR=" clean

current directory: /Library/Ruby/Gems/2.6.0/gems/thin-1.7.2/ext/thin_parser
make "DESTDIR="
compiling parser.c
compiling thin.c
thin.c:242:3: error: implicit declaration of function 'thin_http_parser_init' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  thin_http_parser_init(hp);
  ^
thin.c:242:3: note: did you mean 'http_parser_init'?
./parser.h:41:5: note: 'http_parser_init' declared here
int http_parser_init(http_parser *parser);
    ^
thin.c:260:3: error: implicit declaration of function 'thin_http_parser_init' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  thin_http_parser_init(http);
  ^
thin.c:277:3: error: implicit declaration of function 'thin_http_parser_init' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  thin_http_parser_init(http);
  ^
thin.c:294:3: error: implicit declaration of function 'thin_http_parser_finish' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  thin_http_parser_finish(http);
  ^
thin.c:294:3: note: did you mean 'Thin_HttpParser_finish'?
thin.c:290:7: note: 'Thin_HttpParser_finish' declared here
VALUE Thin_HttpParser_finish(VALUE self)
      ^
thin.c:296:10: error: implicit declaration of function 'thin_http_parser_is_finished' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  return thin_http_parser_is_finished(http) ? Qtrue : Qfalse;
         ^
thin.c:334:5: error: implicit declaration of function 'thin_http_parser_execute' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
    thin_http_parser_execute(http, dptr, dlen, from);
    ^
thin.c:334:5: note: did you mean 'Thin_HttpParser_execute'?
thin.c:317:7: note: 'Thin_HttpParser_execute' declared here

解决方案：

在命令行执行以下命令即可：

gem install thin -- --with-cflags="-Wno-error=implicit-function-declaration"

如果遇到权限错误（例如：You don't have write permissions for the *），则使用以下命令：

sudo gem install thin -- --with-cflags="-Wno-error=implicit-function-declaration"

问题原因：

有可能是XCode的更新版本的原因，XCode新版本将某些编译时问题的错误等级提升了。

如果这个方案解决了您的问题，别忘了点赞♥️，让其他同学也知道这个正确的方法。
另外大家在开发的过程中遇到其他问题，也欢迎在留言区留言交流

参考链接：

1. https://develop.zendesk.com/hc/en-us/community/posts/360051859693-ERROR-to-install-zendesk-apps-tools