Test both abstract and concrete base classes, with simple int/bool data.
This level of complexity is very helpful when setting up director
functionality for a new target language.
Even in the case of just creating a `DerivedClass` this test says:
```
swig/python detected a memory leak of type 'DerivedClass *', no destructor found.
```
even though the destructor is defined in the base class.
Tests that the `%contract` code (viz., each target language's
implementation of SWIG_contract_assert) compiles in C as expected. Update
the note in the source code since `%contract` is in the official
documentation.
Otherwise, generating the `clientdata_prop` modules will duplicate symbols,
leading to linker errors if the resulting modules are linked (or possibly
loaded) simultaneously.
Add test for original syntax when using a single fragment key containing
the list of dependent fragments. I couldn't find a test for this.
Spaces in the fragment list don't seem to work - document it.
The "command" encoder was mostly intended for use in `%rename` - most
uses can be achieved using the "regex" encoder, so we recommend using
that instead.
The "command" encoder suffers from a number of issues - as the
documentation for it admitted, "[it] is extremely slow compared to all
the other [encoders] as it involves spawning a separate process and
using it for many declarations is not recommended" and that it "should
generally be avoided because of performance considerations".
But it's also not portable. The design assumes that `/bin/sh` supports
`<<<` but that's a bash-specific feature so it doesn't work on platforms
where `/bin/sh` is not bash - it fails on Debian, Ubuntu and probably
some other Linux distros, plus most non-Linux platforms. Microsoft
Windows doesn't even have a /bin/sh as standard.
Finally, no escaping of the passed string is done, so it has potential
security issues (though at least with %rename the input is limited to
valid C/C++ symbol names).
Fixes#1806
This is necessary for regex-like renames (where you can't use the #define trick
as is done in many of the %keywordwarn directives). It's now unnecessary to print
the "renaming to '`x`'" code explicitly by the kw.swg files.
Remove redundant NULL checks before free()/delete
The ISO C and C++ standards guarantee that it's safe to call these
on a NULL pointer, so it's not necessary for the calling code to
also check.
Fixes https://sourceforge.net/p/swig/feature-requests/70/
