From 13856719454bc02e090f0784c66a45558be0e9b8 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 14 Dec 2021 09:59:15 -0800
Subject: [PATCH] Work around doc build failure due to docs.rs flags change

---
 build.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/build.rs b/build.rs
index 178c757..946be6e 100644
--- a/build.rs
+++ b/build.rs
@@ -58,7 +58,8 @@ fn main() {
         process::exit(1);
     }
 
-    let semver_exempt = cfg!(procmacro2_semver_exempt);
+    let docs_rs = env::var_os("DOCS_RS").is_some();
+    let semver_exempt = cfg!(procmacro2_semver_exempt) || docs_rs;
     if semver_exempt {
         // https://github.com/dtolnay/proc-macro2/issues/147
         println!("cargo:rustc-cfg=procmacro2_semver_exempt");