get wasm example working

capnp/src/io.rs

@@ -89,8 +89,6 @@ mod std_impls {
 mod no_std_impls {
     use crate::io::{BufRead, Read, Write};
     use crate::{Error, ErrorKind, Result};
-    #[cfg(feature = "alloc")]
-    use alloc::string::ToString;
 
     impl<'a> Write for &'a mut [u8] {
         fn write_all(&mut self, buf: &[u8]) -> Result<()> {

capnp/src/schema.rs

@@ -1,6 +1,10 @@
 //! Convenience wrappers of the datatypes defined in schema.capnp.
 
 #![cfg(feature = "alloc")]
+
+#[cfg(feature = "alloc")]
+use alloc::string::ToString;
+
 use crate::dynamic_value;
 use crate::introspect::{self, RawBrandedStructSchema, RawEnumSchema};
 use crate::private::layout;

capnpc/Cargo.toml

@@ -37,4 +37,4 @@ path = "../capnp"
 # Doing this forces capnpc to define its own mapping from std::io::Read to capnp::io::Read.
 # Fortunately, this is pretty easy, and is just an internal implementation detail.
 default-features=false
-features=[]
+features=["alloc"]

example/wasm-hello-world/wasm-app/src/lib.rs

@@ -8,8 +8,7 @@ use alloc::alloc::{GlobalAlloc, Layout};
 use core::panic::PanicInfo;
 
 // Allocator that fails on every allocation. This is to show that we can read capnproto
-// messages without doing any allocations. Note, however, that capnp::Error does allocate,
-// so for a real application we would want an actual allocator.
+// messages without doing any allocations.
 struct NullAllocator;
 
 unsafe impl GlobalAlloc for NullAllocator {