Fix warnings when compiling runtime. (#4332)

* Remove warnings when compiling runtime.

* Remove dispatch::Result imports.

* Add missing imports.

* Fix missing vecs. #4333

* Fix oom function.

* Remove superfluous import.

* More warnings.

substrate/primitives/consensus/aura/src/inherents.rs

@@ -16,10 +16,7 @@
 
 /// Contains the inherents for the AURA module
 
-use sp_timestamp::TimestampInherentData;
 use inherents::{InherentIdentifier, InherentData, Error};
-use sp_std::result::Result;
-use codec::Decode;
 
 #[cfg(feature = "std")]
 use inherents::{InherentDataProviders, ProvideInherentData};
@@ -86,12 +83,16 @@ impl ProvideInherentData for InherentDataProvider {
 		&self,
 		inherent_data: &mut InherentData,
 	) ->Result<(), Error> {
+		use sp_timestamp::TimestampInherentData;
+
 		let timestamp = inherent_data.timestamp_inherent_data()?;
 		let slot_num = timestamp / self.slot_duration;
 		inherent_data.put_data(INHERENT_IDENTIFIER, &slot_num)
 	}
 
 	fn error_to_string(&self, error: &[u8]) -> Option<String> {
+		use codec::Decode;
+
 		inherents::Error::decode(&mut &error[..]).map(|e| e.into_string()).ok()
 	}
 }

substrate/primitives/core/src/crypto.rs

@@ -18,7 +18,9 @@
 //! Cryptographic utilities.
 // end::description[]
 
-use sp_std::{vec::Vec, hash::Hash};
+use sp_std::hash::Hash;
+#[cfg(feature = "full_crypto")]
+use sp_std::vec::Vec;
 #[cfg(feature = "std")]
 use sp_std::convert::TryInto;
 use sp_std::convert::TryFrom;

substrate/primitives/sr-io/src/lib.rs

@@ -770,6 +770,7 @@ mod allocator_impl {
 	}
 }
 
+/// A default panic handler for WASM environment.
 #[cfg(all(not(feature = "disable_panic_handler"), not(feature = "std")))]
 #[panic_handler]
 #[no_mangle]
@@ -781,9 +782,10 @@ pub fn panic(info: &core::panic::PanicInfo) -> ! {
 	}
 }
 
+/// A default OOM handler for WASM environment.
 #[cfg(all(not(feature = "disable_oom"), not(feature = "std")))]
 #[alloc_error_handler]
-pub extern fn oom(_: core::alloc::Layout) -> ! {
+pub fn oom(_: core::alloc::Layout) -> ! {
 	unsafe {
 		logging::log(LogLevel::Error, "runtime", b"Runtime memory exhausted. Aborting");
 		core::intrinsics::abort();