They are deprecated because they are no longer recommended for use, won’t be as well maintained as non-deprecated equivalents, and could be removed in later years (although removal is unlikely for command-based v1 since it’s a vendordep now and is basically already separate).
With that said, try adding this if statement to your build.gradle:
model {
components {
frcUserProgram(NativeExecutableSpec) {
binaries.all {
if (!(toolChain instanceof VisualCpp))
cppCompiler.args << '-Wno-deprecated-declarations'
}
}
}
}
Again, I strongly caution you against doing this.