Fix alloc + std builds (and test)

.github/workflows/rust.yml

@@ -79,6 +79,7 @@ jobs:
         env:
           DO_FEATURE_MATRIX: true
           DO_SCHEMARS_TESTS: ${{matrix.rust != '1.29.0'}}
+          DO_ALLOC_TESTS: ${{matrix.rust != '1.29.0'}}
         run: ./contrib/test.sh
 
   Embedded:

contrib/test.sh

@@ -1,6 +1,10 @@
 #!/bin/sh -ex
 
-FEATURES="serde serde-std"
+FEATURES="serde serde-std std"
+
+if [ "$DO_ALLOC_TESTS" = true ]; then
+	FEATURES="$FEATURES alloc"
+fi
 
 # Use toolchain if explicitly specified
 if [ -n "$TOOLCHAIN" ]
@@ -30,6 +34,11 @@ if [ "$DO_FEATURE_MATRIX" = true ]; then
     do
         cargo build --all --no-default-features --features="$feature"
         cargo test --all --features="$feature"
+		# All combos of two features
+		for featuretwo in ${FEATURES}; do
+			cargo build --all --no-default-features --features="$feature $featuretwo"
+			cargo test --all --features="$feature $featuretwo"
+		done
     done
 
     # Other combos

src/lib.rs

@@ -39,8 +39,8 @@
 
 #[cfg(any(test, feature="std"))] extern crate core;
 #[cfg(feature="core2")] extern crate core2;
-#[cfg(any(feature = "alloc"))] extern crate alloc;
-#[cfg(any(feature = "std"))] use std as alloc;
+#[cfg(feature = "alloc")] extern crate alloc;
+#[cfg(all(not(feature = "alloc"), feature = "std"))] use std as alloc;
 #[cfg(feature="serde")] pub extern crate serde;
 #[cfg(all(test,feature="serde"))] extern crate serde_test;