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Jay Dee
Asked: 2024-09-22 10:02:21 +0800 CST

understanding c++ --help section

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My understanding is that whoever wrote a program wrote the help section explaining what each argument you can pass to it does, if I type g++ --help I get a write up showing lots of options "in my case I am looking at /usr/bin/arm-none-eabi-g++ --help" but they both look pretty similar

I have output generated by CMake that I was trying to step through and understand, sometimes paths are included with the -I and sometimes -isystem

/usr/bin/arm-none-eabi-g++ \
"-I${PICO_SDK_PATH}/src/rp2_common/pico_atomic/include" \
-isystem "${PICO_SDK_PATH}/src/common/pico_stdlib_headers/include" \

is there any difference?

why can I not see ether -I or -system or -D in the --help wright up?

Near the top of the --help reads

--target-help            Display target specific command line options (including assembler and linker options).

--help={common|optimizers|params|target|warnings|[^]{joined|separate|undocumented}}[,...].

I cannot understand how to open and view this --help= sub help to see if it is explained in sub category's

command-line

1 Answers

  1. Best Answer

    I am actually not sure why the --help text does not have the description of these keys. I can only guess that they are so ancient and well-known that the person who wrote the list of options for --help did not think they need to be included? One would expect them to be in a main --help or --help=common sections but alas.

    But they are included in a full documentation: https://gcc.gnu.org/onlinedocs/

    From the full list you can go to a more specific ones and for example difference between -I and -isystem is described here: https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Directory-Options.html

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