Turned off exception handling support

[Sp3EdeR]

Hello!
I would like to request support for compilation with exception handling turned off.
This is currently an issue within the "narrow" function, which throws "narrowing_error"-s and results in a compilation error on clang.

../thirdparty/gsl-lite/include/gsl/gsl-lite.h:598:9: error: cannot use 'throw' with exceptions disabled
throw narrowing_error();

I would like to request a configuration similar to the contract violation throw/terminate one.

[martinmoene]

Would it be ok to switch on the exisiting gsl_CONFIG_CONTRACT_VIOLATION_THROWS_V?

#if gsl_CONFIG_CONTRACT_VIOLATION_THROWS_V
   throw narrowing_error();
#else 
   std::terminate();
#endif

[Sp3EdeR]

Hello!

Yes, that would work fine technically.
I was just thinking that technically these cases were not contract violations. As such I thought maybe a new configuration option was necessary to perhaps completely disable exceptions, which would of course imply said config option, but not the other way around. If this solution is acceptable for you, I'd be happy to get the update. :)

[martinmoene]

I was just thinking that technically these cases were not contract violations.

That crossed my mind too.

Considering:

• gsl_CONFIG_NARROW_DISCARD_THROWS / gsl_CONFIG_NARROW_DISCARD_TERMINATES
• gsl_CONFIG_NARROW_LOSS_THROWS / gsl_CONFIG_NARROW_LOSS_TERMINATES
• gsl_CONFIG_NARROW_GUARD_THROWS / gsl_CONFIG_NARROW_GUARD_TERMINATES

[Sp3EdeR]

I would personally opt for a generic configuration dealing with whether to throw or terminate.
I imagine most users would not want to customize the behaviour per-feature. It would also possibly increase the configuration options in the future by a large number. This also seems more analoguous with the contract violation configuration, since that can also be used in many features.

I would probably use this or something similar:
gsl_CONFIG_RUNTIME_ERROR_TERMINATES / gsl_CONFIG_RUNTIME_ERROR_THROWS

[viboes]

We can see it as a contract violation of the function requires that narrow_cast doesn't lost information.

[martinmoene]

Added in v0.14.0

I've put it under the umbrella of contract violation, at least initially:

• gsl_CONFIG_CONTRACT_VIOLATION_THROWS
• gsl_CONFIG_CONTRACT_VIOLATION_TERMINATES