From c3d36c94bf4e956af7707771dc93eede6999981c Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Sun, 23 Aug 2020 06:47:06 +0100
Subject: [PATCH] bls12_381: Add feature flags to docs.rs documentation

---
 bls12_381/src/g1.rs       | 2 ++
 bls12_381/src/g2.rs       | 2 ++
 bls12_381/src/lib.rs      | 1 +
 bls12_381/src/pairings.rs | 6 ++++++
 4 files changed, 11 insertions(+)

diff --git a/bls12_381/src/g1.rs b/bls12_381/src/g1.rs
index 7328c3d3c..d30f88240 100644
--- a/bls12_381/src/g1.rs
+++ b/bls12_381/src/g1.rs
@@ -20,6 +20,7 @@ use crate::Scalar;
 ///
 /// Values of `G1Affine` are guaranteed to be in the $q$-order subgroup unless an
 /// "unchecked" API was misused.
+#[cfg_attr(docsrs, doc(cfg(feature = "groups")))]
 #[derive(Copy, Clone, Debug)]
 pub struct G1Affine {
     pub(crate) x: Fp,
@@ -414,6 +415,7 @@ impl G1Affine {
 }
 
 /// This is an element of $\mathbb{G}_1$ represented in the projective coordinate space.
+#[cfg_attr(docsrs, doc(cfg(feature = "groups")))]
 #[derive(Copy, Clone, Debug)]
 pub struct G1Projective {
     x: Fp,
diff --git a/bls12_381/src/g2.rs b/bls12_381/src/g2.rs
index ce59b89d4..b0e7a8763 100644
--- a/bls12_381/src/g2.rs
+++ b/bls12_381/src/g2.rs
@@ -21,6 +21,7 @@ use crate::Scalar;
 ///
 /// Values of `G2Affine` are guaranteed to be in the $q$-order subgroup unless an
 /// "unchecked" API was misused.
+#[cfg_attr(docsrs, doc(cfg(feature = "groups")))]
 #[derive(Copy, Clone, Debug)]
 pub struct G2Affine {
     pub(crate) x: Fp2,
@@ -486,6 +487,7 @@ impl G2Affine {
 }
 
 /// This is an element of $\mathbb{G}_2$ represented in the projective coordinate space.
+#[cfg_attr(docsrs, doc(cfg(feature = "groups")))]
 #[derive(Copy, Clone, Debug)]
 pub struct G2Projective {
     pub(crate) x: Fp2,
diff --git a/bls12_381/src/lib.rs b/bls12_381/src/lib.rs
index 5e8a7db29..7f16f1b47 100644
--- a/bls12_381/src/lib.rs
+++ b/bls12_381/src/lib.rs
@@ -9,6 +9,7 @@
 //! * All operations are constant time unless explicitly noted.
 
 #![no_std]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 // Catch documentation errors caused by code changes.
 #![deny(intra_doc_link_resolution_failure)]
 #![deny(missing_debug_implementations)]
diff --git a/bls12_381/src/pairings.rs b/bls12_381/src/pairings.rs
index 440d3038f..6e9cd4b89 100644
--- a/bls12_381/src/pairings.rs
+++ b/bls12_381/src/pairings.rs
@@ -19,6 +19,7 @@ use alloc::vec::Vec;
 /// Represents results of a Miller loop, one of the most expensive portions
 /// of the pairing function. `MillerLoopResult`s cannot be compared with each
 /// other until `.final_exponentiation()` is called, which is also expensive.
+#[cfg_attr(docsrs, doc(cfg(feature = "pairings")))]
 #[derive(Copy, Clone, Debug)]
 pub struct MillerLoopResult(pub(crate) Fp12);
 
@@ -180,6 +181,7 @@ impl_add_binop_specify_output!(MillerLoopResult, MillerLoopResult, MillerLoopRes
 ///
 /// Typically, $\mathbb{G}_T$ is written multiplicatively but we will write it additively to
 /// keep code and abstractions consistent.
+#[cfg_attr(docsrs, doc(cfg(feature = "pairings")))]
 #[derive(Copy, Clone, Debug, Default)]
 pub struct Gt(pub(crate) Fp12);
 
@@ -449,6 +451,7 @@ impl Group for Gt {
 }
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(all(feature = "pairings", feature = "alloc"))))]
 #[derive(Clone, Debug)]
 /// This structure contains cached computations pertaining to a $\mathbb{G}_2$
 /// element as part of the pairing function (specifically, the Miller loop) and
@@ -509,6 +512,7 @@ impl From<G2Affine> for G2Prepared {
 }
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(all(feature = "pairings", feature = "alloc"))))]
 /// Computes $$\sum_{i=1}^n \textbf{ML}(a_i, b_i)$$ given a series of terms
 /// $$(a_1, b_1), (a_2, b_2), ..., (a_n, b_n).$$
 ///
@@ -565,6 +569,7 @@ pub fn multi_miller_loop(terms: &[(&G1Affine, &G2Prepared)]) -> MillerLoopResult
 }
 
 /// Invoke the pairing function without the use of precomputation and other optimizations.
+#[cfg_attr(docsrs, doc(cfg(feature = "pairings")))]
 pub fn pairing(p: &G1Affine, q: &G2Affine) -> Gt {
     struct Adder {
         cur: G2Projective,
@@ -749,6 +754,7 @@ impl PairingCurveAffine for G2Affine {
 }
 
 /// A [`pairing::Engine`] for BLS12-381 pairing operations.
+#[cfg_attr(docsrs, doc(cfg(feature = "pairings")))]
 #[derive(Clone, Debug)]
 pub struct Bls12;