SW4STM32 - use GCC v4.9 ?
v2.0 doesn’t work either.
I changed the path in: Project Properties > C/C++ Build > Settings > Tool Settings > MCU Settings > Path
but the build is still using the v5.4.1 compiler form the installation.
It looks like it is using the Path from: Project Properties > C/C++ Build > Environment 
So the answer appears to be to delete the setting from: Project Properties > C/C++ Build > Settings > Tool Settings > MCU Settings > Path
And make the setting only in: Project Properties > C/C++ Build > Environment
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