From ec315918cd905cdeed84bc4c5b80087e04d68d5d Mon Sep 17 00:00:00 2001
From: roblabla <unfiltered@roblab.la>
Date: Thu, 11 Jun 2020 14:50:03 +0000
Subject: [PATCH] Cleanly error out when building without the alloc feature

---
 .travis.yml |  2 +-
 src/lib.rs  | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 31f5818..2419d9e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,7 +11,7 @@ script:
   - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo test --verbose --all-features; fi
   - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo bench --verbose --all-features --no-run; fi
   - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then rustup target add thumbv7m-none-eabi; fi
-  - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo build --verbose --no-default-features --target thumbv7m-none-eabi; fi
+  - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo build --verbose --no-default-features --features=alloc --target thumbv7m-none-eabi; fi
   - if [[ "$TRAVIS_NIGHTLY" != "true" ]]; then cargo test --verbose; fi
 
 cache: cargo
diff --git a/src/lib.rs b/src/lib.rs
index e40336c..bbcf2b7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -49,6 +49,9 @@
 //! ```
 #![cfg_attr(not(test), no_std)]
 
+#[cfg(not(feature = "alloc"))]
+compile_error!("This crate does not yet support environments without liballoc. See https://github.com/RustCrypto/RSA/issues/51.");
+
 #[cfg(feature = "alloc")]
 extern crate alloc;
 #[cfg(feature = "std")]
@@ -67,40 +70,55 @@ extern crate hex;
 #[cfg(all(test, feature = "serde"))]
 extern crate serde_test;
 
+#[cfg(feature = "alloc")]
 pub use num_bigint::BigUint;
 
 /// Useful algorithms.
+#[cfg(feature = "alloc")]
 pub mod algorithms;
 
 /// Error types.
+#[cfg(feature = "alloc")]
 pub mod errors;
 
 /// Supported hash functions.
+#[cfg(feature = "alloc")]
 pub mod hash;
 
 /// Supported padding schemes.
+#[cfg(feature = "alloc")]
 pub mod padding;
 
 #[cfg(feature = "pem")]
 pub use pem;
 
+#[cfg(feature = "alloc")]
 mod key;
+#[cfg(feature = "alloc")]
 mod oaep;
 #[cfg(feature = "std")]
 mod parse;
+#[cfg(feature = "alloc")]
 mod pkcs1v15;
+#[cfg(feature = "alloc")]
 mod pss;
+#[cfg(feature = "alloc")]
 mod raw;
 
+#[cfg(feature = "alloc")]
 pub use self::hash::Hash;
+#[cfg(feature = "alloc")]
 pub use self::key::{PublicKey, PublicKeyParts, RSAPrivateKey, RSAPublicKey};
+#[cfg(feature = "alloc")]
 pub use self::padding::PaddingScheme;
 
 // Optionally expose internals if requested via feature-flag.
 
 #[cfg(not(feature = "expose-internals"))]
+#[cfg(feature = "alloc")]
 mod internals;
 
 /// Internal raw RSA functions.
 #[cfg(feature = "expose-internals")]
+#[cfg(feature = "alloc")]
 pub mod internals;