使用string_view编译cpp代码时Coverity报告错误

Question

我编写了一个简单的程序，如下所示：

#include <iostream>
#include <string>
#include <string_view>

using namespace std;

int main(){

    char s[30] = "Hey there!";
    string_view sv(s, 7);

    cout<<"s: "<<s<<endl;
    cout<<"sv: "<<sv<<endl;
    return 0;
}

使用以下命令编译：

cov-build --dir idir --config /home/d3v/cov-analysis-linux64/config/coverity_config.xml g++ --std=c++17 dev.cpp -o dev

控制台上的结果：

Coverity Build Capture (64-bit) version 8.7.1 on Linux 3.10.0-514.21.1.el7.x86_64 x86_64
Internal version numbers: a59584cec3 p-lodi1-push-28091.44.570


[WARNING] Emitted 0 C/C++ compilation units (0%) successfully

0 C/C++ compilation units (0%) are ready for analysis
 For more details, please look at: 
    /home/d3v/d3v/idir/build-log.txt

生成-log.txt文件的尾部：

2020-09-14T11:34:00.997198Z|cov-build|19858|info|> Build time (cov-build overall): 00:00:02.288773
2020-09-14T11:34:00.997198Z|cov-build|19858|info|> 
2020-09-14T11:34:00.997678Z|cov-build|19858|info|> Build time (C/C++ emits total): 00:00:00.903396
2020-09-14T11:34:00.997678Z|cov-build|19858|info|> 
2020-09-14T11:34:00.997678Z|cov-build|19858|info|> 
2020-09-14T11:34:00.997725Z|cov-build|19858|info|> [WARNING] Emitted 0 C/C++ compilation units (0%) successfully
2020-09-14T11:34:00.997725Z|cov-build|19858|info|> 
2020-09-14T11:34:00.997725Z|cov-build|19858|info|> 0 C/C++ compilation units (0%) are ready for analysis
2020-09-14T11:34:00.997725Z|cov-build|19858|info|>  For more details, please look at: 
2020-09-14T11:34:00.997725Z|cov-build|19858|info|>     /home/d3v/d3v/idir/build-log.txt

来自buil-log.txt文件的错误：

[STATUS] Compiling dev.cpp
/home/d3v/cov-analysis-linux64/bin/cov-emit --dir=/home/d3v/d3v/idir --ignore_path=/tmp/cov-d3v/891bff16bbd88b7b80d27daaef3e5a81/cov-configure --ignore_path=/tmp/cov-d3v/891bff16bbd88b7b80d27daaef3e5a81/cov-d3v/2d94633aecadf2b164c84654240d09d0 --add_type_modifier=__coverity___fpreg --add_type_modifier=__coverity_decimal --no_predefined_feature_test_macros --no_stdarg_builtin --incompat_proto --no_predefined_cplusplus -w --no_predefines --comp_ver 8.3.1 --char_bit_size=8 --gnu_carriage_return_line_terminator --wchar_t_keyword --no_multiline_string --no_trigraphs --ignore_calling_convention --enable_80bit_float --enable_128bit_float --macro_stack_pragmas --exceptions --arg_dependent_overload --no_predefines --pre_preinclude /home/d3v/d3v/idir/emit/a7f5e15a0c55/config/988f58815e9372b14b5ed84fa4afe3d5/g++-config-0/coverity-macro-compat.h --pre_preinclude /home/d3v/d3v/idir/emit/a7f5e15a0c55/config/988f58815e9372b14b5ed84fa4afe3d5/g++-config-0/coverity-compiler-compat.h --preinclude /home/d3v/cov-analysis-linux64/config/template-g++-config-3/../user_nodefs.h --c++ --allow_incompat_throw --new_array_args --type_traits_helpers --c++14 --gnu_version 80301 --no_trigraphs --sys_include /opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8 --sys_include /opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8/x86_64-redhat-linux --sys_include /opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8/backward --sys_include /opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/include --sys_include /usr/local/include --sys_include /opt/rh/devtoolset-8/root/usr/include --sys_include /usr/include -D__NO_INLINE__ --type_sizes=e16Pdlx8fiw4s2 --type_alignments=e16Pdlx8fiw4s2 --size_t_type=m --ptrdiff_t_type=l dev.cpp
"/opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../includ
          e/c++/8/type_traits", line 1049: error #255: type name is not allowed
        : public __bool_constant<__is_assignable(_Tp, _Up)>
                                                 ^

"/opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../includ
          e/c++/8/type_traits", line 1049: error #255: type name is not allowed
        : public __bool_constant<__is_assignable(_Tp, _Up)>
                                                      ^

"/opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../includ
          e/c++/8/type_traits", line 1049: error #20: identifier
          "__is_assignable" is undefined
        : public __bool_constant<__is_assignable(_Tp, _Up)>
                                 ^

"/opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../includ
          e/c++/8/type_traits", line 2929: error #255: type name is not allowed
        remove_cv_t<remove_all_extents_t<_Tp>>
        ^

"/opt/rh/devtoolset-8/root/usr/lib/gcc/x86_64-redhat-linux/8/../../../../includ
          e/c++/8/type_traits", line 2928: error #20: identifier
          "__has_unique_object_representations" is undefined
      : bool_constant<__has_unique_object_representations(
                      ^

Emit for file '/home/d3v/d3v/dev.cpp' complete.
[ERROR] 5 errors detected in the compilation of "dev.cpp".
WARNING: cov-emit returned with code 1

生成了二进制文件，但是我无法理解为什么Coverity报告了一个错误，而cov-emit返回了1。请帮助我。

操作系统: CentOS 7

gcc版本: 8.3.1

Answer 1

这种错误表示Coverity工具中存在问题。Coverity编译器cov-emit无法编译本机编译器(在本例中为GCC)接受的源代码。因此，它有某种意想不到的不兼容性。

在这种情况下，我认为主要的问题是Coverity发行版比编译器老，因此缺乏对它的支持。GCC 8.3于2019年2月获释，Coverity 8.7于2017年1月发行.对于每个新支持的编译器版本，Coverity团队可能需要对编译器及其捆绑的头文件进行特定的调整。Coverity文档列出了所支持的编译器版本。

因此，这就提出了两种可能的解决方案：

1. 使用最新的Coverity版本。
2. 使用较早的编译器，在发布Coverity8.7时，该编译器已退出并得到官方支持。

协会免责声明:我曾为Coverity/Synopsys工作。