Allows independently controlling handling of different categories of bugs, such as bounds checks vs. null checks.
User-extensible: Companies can instantiate their own `contract_group` objects for their own categories of contract checks, including for distinguishing contract "levels" like `Normal` vs. `Audit` by just creating those two groups that can then be controlled independently or in combination.
This is not specified in the C++ Core Guidelines as part of GSL, so it should not be documented or supported with a GSL name. And since we don't use it in the GSL repo either, we should just remove it directly. For more about why assumptions are a dangerous blunt instrument, including that they actively eliminate contracts checks including GSL's `Expects` and `Ensures`, see [P2064](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2064r0.pdf).
In microbenchmarks I tried, using `__builtin_expect` to indicate which branch was likely/unlikely was never faster, and often slower, than just omitting. In GSL, this is used only for `Expects` and `Ensures` which are nearly always true, and all processors have long been great at predicting such branches well.
* Use CMAKE_CXX_STANDARD when available
If the use has provided the variable CMAKE_CXX_STANDARD use that instead of providing a default cache variable.
* Typo
* Azure pipeline (#8)
* azure-pipeline test
* nl @ eof
* trimming the pipeline and adding debug steps
* removing redundant lines
* change ctest to script cmd and remove debug
* removed bad char
* added dir change for ctest
* explicit output file and cmake standard
* test cat
* more ctest tests
* injecting failure in test for validation
* another test
* removing bad test
* massive matrix
* added parallel
* commenting everything but xcode out for testing purposes
* uncomment the other tests
* testing some variables
* rename
* changed macos versions
* adding one more layer of templates
* fixing jobs.yml
* idk what i'm doing
* slight modifications
* maybe some spaces will help
* removing 'variables.'
* another test
* adding back pr w/ autocancel
* adding failing test to validate error = failing task
* remove failing test
* trigger master
* nl in steps.yml
* removing deprecation of basic_zstring and derived types. only *string_span should have been deprecated
* Azure pipeline (#8)
* azure-pipeline test
* nl @ eof
* trimming the pipeline and adding debug steps
* removing redundant lines
* change ctest to script cmd and remove debug
* removed bad char
* added dir change for ctest
* explicit output file and cmake standard
* test cat
* more ctest tests
* injecting failure in test for validation
* another test
* removing bad test
* massive matrix
* added parallel
* commenting everything but xcode out for testing purposes
* uncomment the other tests
* testing some variables
* rename
* changed macos versions
* adding one more layer of templates
* fixing jobs.yml
* idk what i'm doing
* slight modifications
* maybe some spaces will help
* removing 'variables.'
* another test
* adding back pr w/ autocancel
* adding failing test to validate error = failing task
* remove failing test
* trigger master
* nl in steps.yml
* remove forced decay of array reference to pointer in span array ctor
narrow() is now in gsl_narrow rather than gsl_util. Include gsl_narrow when exceptions are enabled. Ensures that #include <gsl/gsl> includes entire library as advertised in the documentation.
Co-authored-by: Bowie Owens <bowie.owens@csiro.au>
