How do I set the option to use c99 on Arduino 101?

[jimdgit]

I have extensive code that is in c99.
I have look thru the boards.txt file and can not find a way to turn on c99.
Note that no version of c++ can do what c99 does, so I really need to turn on c99 for this board.
Thanks, Jim

[PaulStoffregen]

duplicate arduino/Arduino#5063

[jimdgit]

Paul, I was advised to post the issue here by facchinm, and he closed the issue so I would post it here.
So I don't really understand why you are marking it duplicate.
I see you have a platform.txt for the 101, but I can't find it on my machine. Also where would platform.local.txt be placed relative to the project file? Because this is what I need to adjust to get c99 mode.
Thanks!

[eriknyquist]

@jimdgit can you post the code that requires C99 to compile, and show the compile error? is it in a .cpp or .c file?

[oqibidipo]

I see you have a platform.txt for the 101, but I can't find it on my machine.

Arduino15/packages/Intel/hardware/arc32/<version>/platform.txt
Arduino15 is where preferences.txt is, you can its location in the Preferences dialog.

[eriknyquist]

OK, I backtracked over the issue on Arduino's github, saw your C file.
Open the file that @oqibidipo mentioned and add -std=gnu99 to compiler.c.flags. See if that works for you.

[jimdgit]

First thank you all for this information!
Arduino15/packages/Intel/hardware/arc32//platform.txt
On windows this is "hidden" in:
C:\Users\AppData\Local
unlike the default ones that are in the install directory (that's why AI could not seem to locate these files)
I will try this tonight and post results.

[jimdgit]

Ok, I can confirm that adding -std=gnu99 to compiler.c.flags. in Arduino15/packages/Intel/hardware/arc32/platform.txt solves all my issues.
Thanks again to @eriknyquist and @oqibidipo for taking time to help me out.

[matthijskooijman]

Can we please fix this in the core itself? The compilation options should match those of the AVR and SAMD cores (which means using gnu11 and gnu++11 standards IIRC).

[eriknyquist]

@matthijskooijman yes, there is -std=gnu11 in the compiler.c.flags here:
https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/platform.txt
So we should match that I guess. I'll look into it.