In a reduced configuration without PEM, PKCS5 or PKCS12, armc5 found that ret
was set but not used. Fixing that lead to a new warning about the variable not
being used at all. Now the variable is only declared when it's needed.
Only effective together with --rom, makes two changes:
- abort in case of build warnings
- skip writing statistics
The goal is to make sure we build cleanly in the configuration used for
measuring code size, with all the compilers we use, both because we care about
that configuration and those compilers, and because any warnings would cast a
shadow on the code size measurements.
Currently the build fails with armc5 due to a pre-existing warning in PK, this
will be fixed in the next commit.
The next commit will also add an all.sh component to make sure we have no
regression in the future. (Which is the motivation for --check skipping
statistics: an all.sh component should probably not leave files around.)
While at it, fix two things:
1. The call to gcc --version was redundant with the echo line below
2. WARNING_CFLAGS shouldn't be overriden with armclang, as it would remove the
-Wall -Wextra and any directory-specific warning (such as
-Wdeclaration-after-statement in library). It's meant to be overriden only
with compilers that don't accept the default value (namely armc5 here).
Some TLS-only code paths were not protected by an #ifdef and while some
compiler are happy to just silently remove them, armc5 complains:
Warning: #111-D: statement is unreachable
Let's make armc5 happy.
This is enabled by default as we generally enable things by default unless
there's a reason not to (experimental, deprecated, security risk).
We need a compile-time option because, even though the functions themselves
can be easily garbage-collected by the linker, implementing them will require
saving 64 bytes of Client/ServerHello.random values after the handshake, that
would otherwise not be needed, and people who don't need this feature
shouldn't have to pay the price of increased RAM usage.
A positive option looks better, but comes with the following compatibility
issue: people using a custom config.h that is not based on the default
config.h and need TLS support would need to manually change their config in
order to still get TLS.
Work around that by making the public option negative. Internally the positive
option is used, though.
In the future (when preparing the next major version), we might want to switch
back to a positive option as this would be more consistent with other options
we have.
