From a95d7dc3303b605b791c9c98e283cdb829053636 Mon Sep 17 00:00:00 2001
From: Andy Freeland <andy@andyfreeland.net>
Date: Sun, 24 Oct 2021 13:15:04 -0700
Subject: [PATCH] Require rustc 1.51+ for `IndexMap::from(array)` and
 `IndexSet::from(array)`

https://github.com/rust-lang/rust/issues/74878 and
https://github.com/rust-lang/rust/issues/65798 were both stabilized in
1.51.
---
 build.rs   | 1 +
 src/map.rs | 3 ++-
 src/set.rs | 3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/build.rs b/build.rs
index 9f9fa054..7c5b6d5e 100644
--- a/build.rs
+++ b/build.rs
@@ -4,5 +4,6 @@ fn main() {
         Some(_) => autocfg::emit("has_std"),
         None => autocfg::new().emit_sysroot_crate("std"),
     }
+    autocfg::new().emit_rustc_version(1, 51);
     autocfg::rerun_path("build.rs");
 }
diff --git a/src/map.rs b/src/map.rs
index 3bdb78ef..8949679b 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -1342,7 +1342,7 @@ where
     }
 }
 
-#[cfg(has_std)]
+#[cfg(all(has_std, rustc_1_51))]
 impl<K, V, const N: usize> From<[(K, V); N]> for IndexMap<K, V, RandomState>
 where
     K: Hash + Eq,
@@ -1857,6 +1857,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(all(has_std, rustc_1_51))]
     fn from_array() {
         let map = IndexMap::from([(1, 2), (3, 4)]);
         let mut expected = IndexMap::new();
diff --git a/src/set.rs b/src/set.rs
index a00e92db..115685cc 100644
--- a/src/set.rs
+++ b/src/set.rs
@@ -840,7 +840,7 @@ where
     }
 }
 
-#[cfg(has_std)]
+#[cfg(all(has_std, rustc_1_51))]
 impl<T, const N: usize> From<[T; N]> for IndexSet<T, RandomState>
 where
     T: Eq + Hash,
@@ -1728,6 +1728,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(all(has_std, rustc_1_51))]
     fn from_array() {
         let set1 = IndexSet::from([1, 2, 3, 4]);
         let set2: IndexSet<_> = [1, 2, 3, 4].into();