Fix docs creation with feature flags

.cargo/config.toml

@@ -1,6 +1,10 @@
 [alias]
-# To test docs locally run: cargo +nightly docs --open
+# To test docs locally run: cargo docs --open
 docs = """doc
 --all-features
 -Zrustdoc-scrape-examples
 """
+
+[build]
+# Necessary for feature flags in the documentation
+rustdocflags = ["--cfg", "docsrs"]

Cargo.toml

@@ -19,6 +19,9 @@ repository = "https://github.com/syrtcevvi/nom-date-parsers"
 [features]
 default = ["numeric", "en"]
 
+# Currently used for building docs for `docsrs` to add `This is supported on feature="..." only.`
+nightly = []
+
 numeric = []
 ru = []
 en = []
@@ -36,5 +39,4 @@ rstest = "0.21.0"
 # document all features
 all-features = true
 rustdoc-args = ["--cfg", "docsrs", "-Znormalize-docs"]
-rustc-args = ["--cfg", "dep_docsrs"]
 cargo-args = ["-Zunstable-options", "-Zrustdoc-scrape-examples"]

src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(doc_auto_cfg)]
+#![cfg_attr(all(docsrs, feature = "nightly"), feature(doc_cfg, doc_auto_cfg))]
 
 pub mod error;
 pub mod i18n;