GCC忽略诊断杂注,而clang不';T
GCC 10.2.0,CLang 11.1.0 我有以下代码:GCC忽略诊断杂注,而clang不';T,gcc,clang,youcompleteme,Gcc,Clang,Youcompleteme,GCC 10.2.0,CLang 11.1.0 我有以下代码: #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wunused-variable"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
uint8_t hour = p[8];
uint8_t min = p[9];
uint8_t sec = p[10];
uint16_t msec = (p[11] * 4);
#pragma GCC diagnostic pop
CLang(由YouCompleteMe vim插件使用)尊重这些pragmas,并且在文件处理过程中不显示任何警告。我可以通过注释这些pragmas out来确认,YCM诊断在相应的行上立即向我显示警告
但是,GCC会忽略它们,我会在控制台日志中看到以下内容:
packet.c:111:26: warning: unused variable ‘msec’ [-Wunused-variable]
111 | uint16_t msec = (p[11] * 4);
| ^~~~
packet.c:110:25: warning: unused variable ‘sec’ [-Wunused-variable]
110 | uint8_t sec = p[10];
| ^~~
packet.c:109:25: warning: unused variable ‘min’ [-Wunused-variable]
109 | uint8_t min = p[9];
| ^~~
packet.c:108:25: warning: unused variable ‘hour’ [-Wunused-variable]
108 | uint8_t hour = p[8];
| ^~~~
用于生成的标志:
CFLAGS="-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -Wall -pedantic -Werror=format-security" CXXFLAGS="-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -Wall -pedantic -Werror=format-security" LDFLAGS="-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now"
这是怎么回事?似乎是GCC中的一个bug
添加1
即使对于这个最简单的程序,情况似乎也是如此:
int main(int argc, char *argv[]) {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
int x;
#pragma GCC diagnostic pop
return 0;
}
测试:
[23:41 viktor@desolve-desktop /tmp]$ clang -Wall main.c
[23:41 viktor@desolve-desktop /tmp]$ gcc -Wall main.c
main.c: In function ‘main’:
main.c:4:9: warning: unused variable ‘x’ [-Wunused-variable]
4 | int x;
| ^
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是为g++设计的,至今仍有9年的历史 似乎与范围界定有关。当我将push/pop
#pragma
s移到变量块之外时,GCC的行为很好。例如:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
uint8_t hour = p[8];
uint8_t min = p[9];
uint8_t sec = p[10];
uint16_t msec = (p[11] * 4);
#pragma GCC diagnostic pop
应更改为:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
{
uint8_t hour = p[8];
uint8_t min = p[9];
uint8_t sec = p[10];
uint16_t msec = (p[11] * 4);
}
#pragma GCC diagnostic pop
然后,clang和gcc都可以正常工作