Fix using from_range with std::vector<>::const_iterator

[burlog]

This pull request addresses a compile error occurring when attempting to instantiate std::vector with a constant value type.

The issue arose in catch_generators_range.hpp, where ResultType was defined as a value_type of const_iterator within GeneratorWrapper<ResultType> which is usually const. This caused a conflict with std::vector, which requires its value_type to be non-const.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.99%. Comparing base (9c5a4cf) to head (8c69645).

Additional details and impacted files

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##            devel    #2926   +/-   ##
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  Coverage   90.99%   90.99%           
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  Files         198      198           
  Lines        8597     8597           
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  Hits         7822     7822           
  Misses        775      775           

[horenmar]

Can you provide a reproducer?

[burlog]

Hm, I see that const_iterators of the standard containers does not have const qualified value_type, so I don't know if my patch is relevant. On the other hand, removing const from value type here probably does not break anything.

I encounter this when I used yaml-cpp for parsing test cases. Simplyfied example is:

#include <catch2/catch_test_macros.hpp>
#include <catch2/generators/catch_generators_range.hpp>

#include <yaml-cpp/yaml.h>

auto yaml = YAML::LoadFile("test.yaml");

TEST_CASE("test case") {
    auto value = GENERATE(from_range(yaml));
}