It is part of the [build] section, not a [target].
# custom flags to pass to all compiler invocations that target $triple
# this value overrides build.rustflags when both are present
rustflags = ["..", ".."]
-# Whether or not to enable incremental compilation
-incremental = true
[target.'cfg(...)']
# Similar for the $triple configuration, but using the `cfg` syntax.
target = "triple" # build for the target triple
target-dir = "target" # path of where to place all generated artifacts
rustflags = ["..", ".."] # custom flags to pass to all compiler invocations
+incremental = true # whether or not to enable incremental compilation
[term]
verbose = false # whether cargo provides verbose output