https://github.com/dlang/dmd/blob/master/src/dmd/compiler.d#L75

On Tuesday, 15 January 2019 at 17:52:35 UTC, Machine Code wrote:
> https://github.com/dlang/dmd/blob/master/src/dmd/compiler.d#L75

https://dlang.org/spec/lex.html#token_strings
:)

On Tuesday, 15 January 2019 at 17:52:35 UTC, Machine Code wrote:
> https://github.com/dlang/dmd/blob/master/src/dmd/compiler.d#L75

It is a string literal that must be made out of D code tokens.

In my blog this week, I talked about some code that uses them:

http://dpldocs.info/this-week-in-d/Blog.Posted_2019_01_14.html#the-generated-client

You can see how it syntax highlights as code, but is semantically a string. The code inside is passed to mixin, so this hybrid appearance works well.

On Tuesday, 15 January 2019 at 17:56:10 UTC, SrMordred wrote:
> On Tuesday, 15 January 2019 at 17:52:35 UTC, Machine Code wrote:
>> https://github.com/dlang/dmd/blob/master/src/dmd/compiler.d#L75
>
> https://dlang.org/spec/lex.html#token_strings
> :)

I had just infered from the commend in the code "The D code to be generated is provided as D source code in the form of a string."

then I tried:

	auto s = q{ foo(); return 10 };
	writeln(s);

Then whoa. What a feature! I'm not aware of any language with this feature. Amazing.
Thank for your answer as well :)