这是由于配置中没有指定依赖路径导致的，在c_cpp_properties.json中includePath的默认配置只有当前目录，需要将系统依赖加入。

在命令行里面输入

gcc -v -E -x c++ -

在结果里面找到头文件目录,然后添加到includepath中。

运行结果如下:

C:\Users\wangzp>gcc -v -E -x c++ -                                                                                                                                                                                                           
Using built-in specs.                                                                                                                                                                                                                        
COLLECT_GCC=gcc                                                                                                                                                                                                                              
Target: x86_64-w64-mingw32                                                                                                                                                                                                                   
Configured with: ../../../src/gcc-8.1.0/configure --host=x86_64-w64-mingw32 --
build=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --prefix=/mingw64 --with-
sysroot=/c/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64 --enable-shared --enable
static --disable-multilib --enable-languages=c,c++,fortran,lto --enable-libstdcxx-
time=yes --enable-threads=win32 --enable-libgomp --enable-libatomic --enable-lto --enable-graphite --enable-checking=release --enable-fully-dynamic-string --enable-version-specific-runtime-libs --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-bootstrap --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-gnu-as --with-gnu-ld --with-arch=nocona --with-
tune=core2 --with-libiconv --with-system-zlib --with-
gmp=/c/mingw810/prerequisites/x86_64-w64-mingw32-static --with-
mpfr=/c/mingw810/prerequisites/x86_64-w64-mingw32-static --with-
mpc=/c/mingw810/prerequisites/x86_64-w64-mingw32-static --with-
isl=/c/mingw810/prerequisites/x86_64-w64-mingw32-static --with-pkg
version='x86_64-win32-seh-rev0, Built by MinGW-W64 project' --with-
bugurl=https://sourceforge.net/projects/mingw-w64 CFLAGS='-O2 -pipe -fno-ident -
I/c/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64/opt/include -
I/c/mingw810/prerequisites/x86_64-zlib-static/include -
I/c/mingw810/prerequisites/x86_64-w64-mingw32-static/include' CXXFLAGS='-O2 -pipe -
fno-ident -I/c/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64/opt/include -
I/c/mingw810/prerequisites/x86_64-zlib-static/include -
I/c/mingw810/prerequisites/x86_64-w64-mingw32-static/include' CPPFLAGS=' -
I/c/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64/opt/include -
I/c/mingw810/prerequisites/x86_64-zlib-static/include -
I/c/mingw810/prerequisites/x86_64-w64-mingw32-static/include' LDFLAGS='-pipe -fno-
ident -L/c/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64/opt/lib -
L/c/mingw810/prerequisites/x86_64-zlib-static/lib -L/c/mingw810/prerequisites/x86_64-
w64-mingw32-static/lib '                                                                                                                                                            
Thread model: win32                                                                                                                                                                                                                          
gcc version 8.1.0 (x86_64-win32-seh-rev0, Built by MinGW-W64 project)                                                                                                                                                                        
COLLECT_GCC_OPTIONS='-v' '-E' '-mtune=core2' '-march=nocona'                                                                                                                                                                                  
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-
rev0/mingw64/bin/../libexec/gcc/x86_64-w64-mingw32/8.1.0/cc1plus.exe -E -quiet -v -
iprefix C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-
rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/ -U_REENTRANT - -mtune=core2 -
march=nocona                                                                                                                                                                               
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++"                                                                               
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/x86_64-w64-
mingw32"                                                            
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/backward"                                                                      
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/include"                                                                                   
ignoring nonexistent directory "C:/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64C:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/../../../../include"                                                                                   
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-
rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/include-fixed"                                                                             
ignoring duplicate directory "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/8.1.0/../../../../x86_64-w64-
mingw32/include"                                                    
ignoring nonexistent directory "C:/mingw810/x86_64-810-win32-seh-rt_v6-rev0/mingw64/mingw/include"                                                                                                                                           
#include "..." search starts here:                                                                                                                                                                                                           
#include <...> search starts here:                                                                                                                                                                                                            
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++                                                                                                                     
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/x86_64-w64-mingw32                                                                                                  
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/backward                                                                                                            
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include                                                                                                                         
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include-fixed                                                                                                                   
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/../../../../x86_64-w64-mingw32/include                                                                                         
End of search list.                                                                                                                           

配置IntelliSense
扩展程序会根据当前系统环境配置基本信息，因此有可能配置不完整，这时需要通过生成c_cpp_properties.json文件来配置缺少的信息：

ctrl+shift+P打开Command Palette,运行

C/C++: Edit configurations...

生成c_cpp_properties.json：

{
    "configurations": [
        {
            "name": "Win32",
            "includePath": [
                "${workspaceFolder}/**",              
            ],
            "defines": [
                "_DEBUG",
                "UNICODE",
                "_UNICODE"
            ],
            "windowsSdkVersion": "8.1",
            "compilerPath": "cl.exe",
            "cStandard": "c17",
            "cppStandard": "c++17",
            "intelliSenseMode": "windows-msvc-x86"
        }
    ],
    "version": 4
}

这是Windows平台上默认生成的c_cpp_properties.json文件，可在这个文件中添加配置。

将以下路径添加到includePath中

C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++                                                                                                                     
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/x86_64-w64-mingw32                                                                                                  
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/backward                                                                                                            
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include                                                                                                                         
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include-fixed                                                                                                                   
C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/../../../../x86_64-w64-mingw32/include   

最终效果为：

{
    "configurations": [
        {
            "name": "Win32",
            "includePath": [
                "${workspaceFolder}/**",
                "C:/Program Files (x86)/Microsoft Visual Studio 10.0/VC/include/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/x86_64-w64-mingw32/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/backward/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/include-fixed/*",
                "C:/Program Files/mingw-w64/x86_64-8.1.0-win32-seh-rt_v6-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.1.0/../../../../x86_64-w64-mingw32/include/*"

            ],
            "defines": [
                "_DEBUG",
                "UNICODE",
                "_UNICODE"
            ],
            "windowsSdkVersion": "8.1",
            "compilerPath": "cl.exe",
            "cStandard": "c17",
            "cppStandard": "c++17",
            "intelliSenseMode": "windows-msvc-x86"
        }
    ],
    "version": 4
}

参考文献：

https://blog.csdn.net/u013250861/article/details/127813201