In the future we can expect many more matchers, so let's give them
a place to live.
Also moved matcher-related internal files to `internal` subfolder.
Ideally we should sort out all of our source code, but that will
have to come later.
This commit also forbids composing lvalues of composed matchers, as
per previous deprecation notice. I do not expect this to be contentious
in practice, because there was a bug in that usage for years, and
nobody complained.
Given that in the 2 or so years that matchers are thing nobody complained,
it seems that people do not actually write this sort of code, and the
possibility will be removed in v3. However, to avoid correctness bugs,
we will have to support this weird code in v2.
This commit extends the Matchers feature with the ability to have type-independent (e.g. templated) matchers. This is done by adding a new base type that Matchers can extend, `MatcherGenericBase`, and overloads of operators `!`, `&&` and `||` that handle matchers extending `MatcherGenericBase` in a special manner.
These new matchers can also take their arguments as values and non-const references.
Closes#1307Closes#1553Closes#1554
Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>
Now that the recommended distribution and usage method is proper
library, users can just avoid including the matcher headers to get
basically the same effect.
