The change in commit v3.5.0-rc1~198^2 (Ninja: Always re-run custom
commands that have symbolic dependencies, 2015-11-19) broke the
byproducts feature added by commit v3.2.0-rc1~340^2~2 (Add an option for
explicit BYPRODUCTS of custom commands, 2014-11-13) when SYMBOLIC
outputs also appear. This case occurs with AUTORCC-generated custom
targets because the output is SYMBOLIC (to always run) and the generated
file is a byproduct (for restat so dependents do not run unnecessarily).
The two use cases conflict because Ninja does not support per-output
restat. Favor restat whenever byproducts are present because it is
required for byproducts to work correctly. In use cases where we want
an always-run chain we simply will not be able to also use byproducts.
If a custom command has a SYMBOLIC output (that is never actually
created) then do not mark the custom command build statement as
'restat'. Otherwise other custom commands that depend on the symbolic
output may not always re-run because after running the first custom
command Ninja 'restat' will detect that the output timestamp did not
change and skip its dependents.
This was observed with the ExternalProject BUILD_ALWAYS option where
Ninja would not re-run the 'install' step each time 'build' re-runs.
Classify .manifest sources separately, add dependencies on them, and
pass them to the MS manifest tool to merge with linker-generated
manifest files.
Inspired-by: Gilles Khouzam <gillesk@microsoft.com>
Brad King
Gregor Jasny