docs: swap doc_auto_cfg with doc_cfg

In rust-lang/rust#138907, the `doc_auto_cfg`
feature was subsumed by `doc_cfg`. This does overall look like we're on
a path toward stabilization, which is great.

One problem here though is that a bunch of crates use the `cfg` `docsrs`
to enable `doc_auto_cfg`. So if we enable it, then it causes those
crates to stop compiling. This is overall very annoying, and I don't
know how to unfuck things. So I changed the `cfg` knob to `docsrs_regex`
which, doesn't quite provide a guarantee, but gets us closer to being
masters of our own destiny.

Author: BurntSushi

.github/workflows/ci.yml

@@ -55,7 +55,7 @@ jobs:
           rust: stable-x86_64-gnu
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -107,7 +107,7 @@ jobs:
         - s390x-unknown-linux-gnu
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install and configure Cross
       run: |
         # In the past, new releases of 'cross' have broken CI. So for now, we
@@ -142,7 +142,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -152,6 +152,26 @@ jobs:
     - name: Build docs
       run: cargo doc --verbose
 
+  # This job checks the docsrs configuration.
+  #
+  # This is important because we enable `doc_cfg`, which is an unstable
+  # feature that can (and has) broken.
+  docsrs:
+    runs-on: ubuntu-latest
+    env:
+      RUSTDOCFLAGS: "-D rustdoc::broken_intra_doc_links --cfg docsrs_regex"
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v5
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@master
+      with:
+        toolchain: nightly
+    - name: Basic build
+      run: cargo build --verbose
+    - name: Build docs
+      run: cargo doc --verbose
+
   # This job runs many more tests for the regex crate proper. Basically,
   # it repeats the same test suite for a bunch of different crate feature
   # combinations. There are so many features that exhaustive testing isn't
@@ -163,7 +183,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -176,7 +196,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -189,7 +209,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -202,7 +222,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -217,7 +237,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -234,7 +254,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:

CHANGELOG.md

@@ -1,3 +1,14 @@
+1.12.2 (2025-10-13)
+===================
+This release fixes a `cargo doc` breakage on nightly when `--cfg docsrs` is
+enabled. This caused documentation to fail to build on docs.rs.
+
+Bug fixes:
+
+* [BUG #1305](https://github.com/rust-lang/regex/issues/1305):
+Switches the `doc_auto_cfg` feature to `doc_cfg` on nightly for docs.rs builds.
+
+
 1.12.1 (2025-10-10)
 ===================
 This release makes a bug fix in the new `regex::Captures::get_match` API

Cargo.toml

@@ -229,13 +229,23 @@ name = "integration"
 all-features = true
 # Since this crate's feature setup is pretty complicated, it is worth opting
 # into a nightly unstable option to show the features that need to be enabled
-# for public API items. To do that, we set 'docsrs', and when that's enabled,
-# we enable the 'doc_auto_cfg' feature.
+# for public API items. To do that, we set 'docsrs_regex', and when that's
+# enabled, we enable the 'doc_cfg' feature.
 #
 # To test this locally, run:
 #
-#     RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features
-rustdoc-args = ["--cfg", "docsrs"]
+#     RUSTDOCFLAGS="--cfg docsrs_regex" cargo +nightly doc --all-features
+#
+# Note that we use `docsrs_regex` instead of the more standard `docsrs` because
+# other crates use that same `cfg` knob. And since we are enabling a nightly
+# feature, they sometimes break. By using our "own" `cfg` knob, we are closer
+# to being masters of our own destiny.
+rustdoc-args = ["--cfg", "docsrs_regex"]
+
+# This squashes the (AFAIK) erroneous warning that `docsrs_regex` is not a
+# valid `cfg` knob.
+[lints.rust]
+unexpected_cfgs = { level = "allow", check-cfg = ['cfg(docsrs_regex)'] }
 
 [profile.release]
 debug = true

regex-automata/Cargo.toml

@@ -109,3 +109,26 @@ features = ["atty", "humantime", "termcolor"]
 [[test]]
 path = "tests/lib.rs"
 name = "integration"
+
+[package.metadata.docs.rs]
+# We want to document all features.
+all-features = true
+# Since this crate's feature setup is pretty complicated, it is worth opting
+# into a nightly unstable option to show the features that need to be enabled
+# for public API items. To do that, we set 'docsrs_regex', and when that's
+# enabled, we enable the 'doc_cfg' feature.
+#
+# To test this locally, run:
+#
+#     RUSTDOCFLAGS="--cfg docsrs_regex" cargo +nightly doc --all-features
+#
+# Note that we use `docsrs_regex` instead of the more standard `docsrs` because
+# other crates use that same `cfg` knob. And since we are enabling a nightly
+# feature, they sometimes break. By using our "own" `cfg` knob, we are closer
+# to being masters of our own destiny.
+rustdoc-args = ["--cfg", "docsrs_regex"]
+
+# This squashes the (AFAIK) erroneous warning that `docsrs_regex` is not a
+# valid `cfg` knob.
+[lints.rust]
+unexpected_cfgs = { level = "allow", check-cfg = ['cfg(docsrs_regex)'] }

regex-automata/src/dfa/regex.rs

@@ -70,11 +70,10 @@ define_regex_type!(
     /// a match.
     ///
     /// The type of the DFA used by a `Regex` corresponds to the `A` type
-    /// parameter, which must satisfy the [`Automaton`] trait. Typically,
-    /// `A` is either a [`dense::DFA`](crate::dfa::dense::DFA) or a
-    /// [`sparse::DFA`](crate::dfa::sparse::DFA), where dense DFAs use more
-    /// memory but search faster, while sparse DFAs use less memory but search
-    /// more slowly.
+    /// parameter, which must satisfy the [`Automaton`] trait. Typically, `A`
+    /// is either a [`dense::DFA`] or a [`sparse::DFA`], where dense DFAs use
+    /// more memory but search faster, while sparse DFAs use less memory but
+    /// search more slowly.
     ///
     /// # Crate features
     ///

regex-automata/src/lib.rs

@@ -603,10 +603,9 @@ enables `alloc` and `nfa-thompson`.
 )]
 // We generally want all types to impl Debug.
 #![warn(missing_debug_implementations)]
-// No clue why this thing is still unstable because it's pretty amazing. This
-// adds Cargo feature annotations to items in the rustdoc output. Which is
+// This adds Cargo feature annotations to items in the rustdoc output. Which is
 // sadly hugely beneficial for this crate due to the number of features.
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs_regex, feature(doc_cfg))]
 
 // I have literally never tested this crate on 16-bit, so it is quite
 // suspicious to advertise support for it. But... the regex crate, at time

regex-syntax/Cargo.toml

@@ -43,10 +43,20 @@ arbitrary = { version = "1.3.0", features = ["derive"], optional = true }
 all-features = true
 # Since this crate's feature setup is pretty complicated, it is worth opting
 # into a nightly unstable option to show the features that need to be enabled
-# for public API items. To do that, we set 'docsrs', and when that's enabled,
-# we enable the 'doc_auto_cfg' feature.
+# for public API items. To do that, we set 'docsrs_regex', and when that's
+# enabled, we enable the 'doc_cfg' feature.
 #
 # To test this locally, run:
 #
-#     RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features
-rustdoc-args = ["--cfg", "docsrs"]
+#     RUSTDOCFLAGS="--cfg docsrs_regex" cargo +nightly doc --all-features
+#
+# Note that we use `docsrs_regex` instead of the more standard `docsrs` because
+# other crates use that same `cfg` knob. And since we are enabling a nightly
+# feature, they sometimes break. By using our "own" `cfg` knob, we are closer
+# to being masters of our own destiny.
+rustdoc-args = ["--cfg", "docsrs_regex"]
+
+# This squashes the (AFAIK) erroneous warning that `docsrs_regex` is not a
+# valid `cfg` knob.
+[lints.rust]
+unexpected_cfgs = { level = "allow", check-cfg = ['cfg(docsrs_regex)'] }

regex-syntax/src/lib.rs

@@ -168,7 +168,9 @@ The following features are available:
 #![forbid(unsafe_code)]
 #![deny(missing_docs, rustdoc::broken_intra_doc_links)]
 #![warn(missing_debug_implementations)]
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+// This adds Cargo feature annotations to items in the rustdoc output. Which is
+// sadly hugely beneficial for this crate due to the number of features.
+#![cfg_attr(docsrs_regex, feature(doc_cfg))]
 
 #[cfg(any(test, feature = "std"))]
 extern crate std;

src/lib.rs

@@ -1319,6 +1319,9 @@ this for literal optimizations.
 #![no_std]
 #![deny(missing_docs)]
 #![cfg_attr(feature = "pattern", feature(pattern))]
+// This adds Cargo feature annotations to items in the rustdoc output. Which is
+// sadly hugely beneficial for this crate due to the number of features.
+#![cfg_attr(docsrs_regex, feature(doc_cfg))]
 #![warn(missing_debug_implementations)]
 
 #[cfg(doctest)]