Minor cleanups

soroban-env-host/src/host/metered_xdr.rs

@@ -1,15 +1,14 @@
 use crate::{
     budget::Budget,
-    xdr::ContractCostType,
-    xdr::{ReadXdr, ScBytes, WriteXdr},
+    xdr::{
+        ContractCostType, DepthLimitedWrite, ReadXdr, ScBytes, ScErrorCode, ScErrorType, WriteXdr,
+        DEFAULT_XDR_RW_DEPTH_LIMIT,
+    },
     BytesObject, Host, HostError,
 };
 use std::io::Write;
 
 use sha2::{Digest, Sha256};
-use soroban_env_common::xdr::{
-    DepthLimitedWrite, ScErrorCode, ScErrorType, DEFAULT_XDR_RW_DEPTH_LIMIT,
-};
 
 struct MeteredWrite<'a, W: Write> {
     budget: &'a Budget,

soroban-env-host/src/host/validity.rs

@@ -58,16 +58,10 @@ impl Host {
         a: usize,
         b: usize,
     ) -> Result<usize, HostError> {
-        let lim = u32::MAX as usize;
-        if a > lim || b > lim || a > (lim - b) {
-            Err(self.err(
-                ScErrorType::Value,
-                ScErrorCode::ExceededLimit,
-                "sum of sizes exceeds u32::MAX",
-                &[],
-            ))
-        } else {
-            Ok(a + b)
-        }
+        let a = u32::try_from(a).map_err(|_| self.err_arith_overflow())?;
+        let b = u32::try_from(b).map_err(|_| self.err_arith_overflow())?;
+        a.checked_add(b)
+            .ok_or_else(|| self.err_arith_overflow())
+            .map(|u| u as usize)
     }
 }

soroban-env-host/src/lib.rs

@@ -6,13 +6,9 @@
 //! crate for use by host (or contract local-testing) code. Most of the type and
 //! module definitions visible here are actually defined in the common crate.
 //!
-//! It may seem unusual to configure a contract host _without_ a VM, but this
-//! configuration makes more sense when considering that Soroban supports a
-//! "local testing" configuration where host and guest code are _both compiled
-//! natively_ and linked together for a faster and richer debugging and testing
-//! experience. When testing this way, developers may also wish to enable the
-//! `"testutils"` feature, which enables an interface on [Host] for registering
-//! other test contracts by ID.
+//! When unit-testing contracts natively (not using wasm), developers may also
+//! wish to enable the `"testutils"` feature, which enables an interface on
+//! [Host] for registering other test contracts by ID.
 //!
 //! The [Host] type provides some facilities above and beyond just the [Env]
 //! trait, including:
@@ -55,6 +51,7 @@ pub mod auth;
 pub mod vm;
 pub use vm::Vm;
 #[cfg(any(test, feature = "testutils"))]
+#[doc(hidden)]
 pub mod cost_runner;
 pub mod storage;
 #[cfg(test)]