This is a huge patch that should be a global NOP.
For unix type platforms it enables -Wconversion to issue warnings (-> error)
for all automatic casts that seem less than ideal but are normally concealed
by the toolchain.
This is things like passing an int to a size_t argument. Once enabled, I
went through all args on my default build (which build most things) and
tried to make the removed default cast explicit.
With that approach it neither change nor bloat the code, since it compiles
to whatever it was doing before, just with the casts made explicit... in a
few cases I changed some length args from int to size_t but largely left
the causes alone.
From now on, new code that is relying on less than ideal casting
will complain and nudge me to improve it by warnings.
On an error path, we might not have a valid spa / lejp to destroy.
In that case, don't hurl ourselves into calling a
function pointer that can be NULL for the destroy cb.
This is complicated by the fact extern on a function declaration implies
visibility... we have to make LWS_EXTERN empty when building static.
And, setting target_compile_definitions() doesn't work inside macros,
so it has to be set explicitly for the plugins.
Checking the symbol status needs nm -C -D as per
https://stackoverflow.com/questions/37934388/symbol-visibility-not-working-as-expected
after this patch, libwebsockets.a shows no symbols when checked like that and
the static-linked minimal examples only show -U for their other dynamic
imports.
In a handful of cases we use LWS_EXTERN on extern data declarations,
those then need to change to explicit extern.
lejp_parse() return type is an int... but in the function, the temp
for it is a char. This leads to badness that is currently worked
around by casting the return through a signed char type.
But that leads to more badness since if there's >127 bytes of buffer
left after the end of the JSON object, we misreport it.
Bite the bullet and fix the temp type, and fix up all the guys
who were working around it at the caller return casting to use the
resulting straight int.
If you are using this api, remove any casting you may have cut-
and-pasted like this
n = (int)(signed char)lejp_parse(...);
... to just be like this...
n = lejp_parse(...);
lejp-conf isn't the only user that needs to generate human-readable
JSON parsing error stacks.
Build it in with lejp and introduce an error code -> string api
