build: drop unstable doc_cfg

With `alloc` stabilized, we want to get rid of any other unstable
feature. So replace the `doc_cfg` feature with a simple `doctest =
false`. As sad as it is, there currently seems to be no other way to
get this working. Meh.. Lets see what the future brings.

Signed-off-by: David Rheinsberg <david.rheinsberg@gmail.com>

Author: dvdhrm

Cargo.toml

@@ -25,3 +25,10 @@ keywords = [
 license = "Apache-2.0 OR LGPL-2.1-or-later"
 readme = "README.md"
 repository = "https://github.com/r-util/r-efi-string"
+
+[lib]
+# We do not link to an allocator by default, because we allow the crate user to
+# select one. This, however, makes `doctest` fall over. Sadly, there is no
+# stabilized way to conditionally compile in code for doctests. Therefore, we
+# disable them for now. Maybe some day `cfg(doctest)` will be stabilized...
+doctest = false

src/lib.rs

@@ -8,14 +8,8 @@
 //!
 //!  * `[str16]`: UCS-2 based strings, which use a `u16` based encoding.
 
-// We currently need some unstable features:
-//
-//  * We use `doc_cfg` to run conditional code in rustdoc compilations. This is, again, related to
-//    `no_std`, since we want to make sure the rustdoc examples still work correctly.
-#![feature(doc_cfg)]
-
-// We do not depend on `libstd`, but pull it in for our unit tests and documentation.
-#![cfg_attr(not(any(test, rustdoc)), no_std)]
+// We do not depend on `libstd`, but pull it in for our unit tests.
+#![cfg_attr(not(test), no_std)]
 
 // We provide converters to/from `alloc::string::String`, so import `liballoc`.
 extern crate alloc;