## in a code snippet confuses quickbook C++ syntax highlighting

[Richard <legalize@…>]

If I include the following code snippet in a quickbook file:

```
#define HELLO_WORLD_TEST_CASE(name_) \
    BOOST_FIXTURE_TEST_CASE(hello_world_##name_, hello_world_fixture)
```

quickbook complains about the token pasting operator ##, believing it to be a preprocessor directive like #define. It issues a warning such as:

warning: in column:41, unexpected character: #

and colors the second "#name_" in the color of a preprocessor directive.

[Richard <legalize@…>]

...and colors "#name_" in the color of a preprocessor directive.

[Daniel James]

(In [84063]) Support the token pasting operator in C++ code blocks. Refs #8510.

[Daniel James]

Merged to release in [84252].