¿Cuáles son los directorios de inclusión predeterminados de GCC?

Cuando compilo un archivo fuente muy simple con gcc, no tengo que especificar la ruta a los archivos de inclusión estándar como stdio o stdlib.

¿Cómo sabe GCC cómo encontrar estos archivos?

¿Tiene el /usr/include ruta cableada en el interior, o obtendrá las rutas de otros componentes del sistema operativo?

Respuestas:

Para averiguar las rutas predeterminadas utilizadas por gcc /g++ , así como sus prioridades, debe examinar la salida de los siguientes comandos:

1. Para C :

    gcc -xc -E -v -
 

2. Para C++ :

    gcc -xc++ -E -v -
 

El mérito es del equipo de creadores de Qt .

Algunas respuestas de código

    gcc -xc -E -v - 

    gcc -xc++ -E -v - 

$ echo | gcc -Wp,-v -x c++ - -fsyntax-only ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include-fixed" ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../x86_64-redhat-linux/include" #include "..." search starts here: #include <...>
search starts here:  /usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2  /usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2/x86_64-redhat-linux  /usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2/backward  /usr/lib/gcc/x86_64-redhat-linux/4.8.2/include  /usr/local/include  /usr/include End of search list. 

⋮ /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../arm-none-eabi/include/newlib-nano   /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1 /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1/arm-none-eabi/thumb/v7e-m/nofp
/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1/backward    /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/include  /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/include-fixed
/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include
    ⋮ 

⋮ /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1 /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1/arm-none-eabi
    /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include/c++/9.2.1/backward    /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/include /opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/include-fixed
/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/include
    ⋮ 

$(gcc -print-prog-name=cc1) -v