Support expected output in compile-time failure test

[ldionne]

For example, I want to be able to check that a specific error message is emitted (a static_assert, say). The way I do that right now is by putting the following in the source file:

// in foo.cpp
int main() {
  // MESSAGE[Incomplete definition of your concept map]
  auto const& map = dyno::complete_concept_map<Fooable, int>(dyno::concept_map<Fooable, int>);
}

I then create a compile_fail test for foo.cpp and that checks whether there's an expected message. See https://github.com/ldionne/dyno/blob/master/cmake/CompileFailTest.cmake for an implementation.

[pfultz2]

I think this can be accomplished with the PASS_REGULAR_EXPRESSION or FAIL_REGULAR_EXPRESSION, but let me create a test for this use case.

[ldionne]

I don't think it works (I remember trying this first), and it's convenient to put the error message in the source file, close to the line where the error happens. If you don't put any message, it just checks for failure.

[pfultz2]

I don't think it works

That looks like what you do in the link you sent.

it's convenient to put the error message in the source file

Yea, I can add option to parse the output from the source file.

[ldionne]

That looks like what you do in the link you sent.

Sure, but there I don't say WILL_FAIL, I just say PASS_REGULAR_EXPRESSION. And if I don't want any message, I need to specify WILL_FAIL instead. This is backwards, and that's why I think it's nice to have this encapsulated in something like bcm_test.

[pfultz2]

I actually don't see it as backwards. However, I do see it very useful to add a feature to parse this from the source files.