IWYU runs always with -march=x86-64

[2342343243234]

Unfortunately size_t is still 4 bytes on my machine.

Adding -m64 to the commandline as mentioned here solves the problem for me.

There seems to be no way of adding anything to the iwyu commandline. Maybe it's possible to have an optional file in the iwyu directory which can be read by IncludeToolBox and passed verbatim on the commandline when invoking iwyu?

[Wumpf]

I tried choosing the architecture dynamically, but hit problems with iwyu itself. See here:
https://github.com/Wumpf/IncludeToolbox/blob/master/IncludeToolbox/IncludeWhatYouUse/IWYU.cs#L259
Do you know how to run iwyu with x86 on windows? I tried and got error: unknown target CPU 'x86'

You can add additional iwyu commands in the settings dialog: Include Toolbox > Include-What-You-Use > iwyu options > Additional Parameters