[WIP] Deny OOM, embrace try_reserve

.github/workflows/rust.yml

@@ -48,7 +48,7 @@
           "uses": "actions-rs/cargo@v1",
           "with": {
             "command": "check",
-            "args": "--all-features"
+            "args": "--features std,derive"
           },
           "name": "Run `cargo check`"
         },
@@ -158,7 +158,7 @@ fi",
           "uses": "actions-rs/cargo@v1",
           "with": {
             "command": "clippy",
-            "args": "--all-features -- -D warnings"
+            "args": "--features std,derive -- -D warnings"
           },
           "name": "Run `cargo clippy`"
         }
@@ -213,7 +213,7 @@ fi",
           "uses": "actions-rs/tarpaulin@v0.1",
           "with": {
             "version": "0.19.1",
-            "args": "--all --all-features"
+            "args": "--all --features std,derive"
           }
         },
         {

.github/workflows/strict_oom.yml

@@ -0,0 +1,70 @@
+{
+  "name": "strict OOM",
+  "on": {
+    "push": {
+      "branches": [
+        "trunk",
+        "v*.x",
+        "ci/*"
+      ]
+    },
+    "pull_request": {
+      "branches": [
+        "trunk",
+        "v*.x"
+      ]
+    }
+  },
+  "jobs": {
+    "no_oom": {
+      "name": "Strict OOM checks",
+      "runs-on": "ubuntu-latest",
+      "steps": [
+        {
+          "uses": "actions/checkout@v2",
+          "name": "Checkout"
+        },
+        {
+          "uses": "actions-rs/toolchain@v1",
+          "with": {
+            "profile": "minimal",
+            "toolchain": "nightly",
+            "components": "rust-src",
+            "override": true
+          },
+          "name": "Install Rust nightly"
+        },
+        {
+          "run": "cargo build --no-default-features --features unstable-strict-oom-checks -Z build-std=core,alloc --target x86_64-unknown-linux-gnu",
+          "env": {
+            "RUSTFLAGS": "--cfg no_global_oom_handling"
+          }
+        }
+      ]
+    },
+    "miri": {
+      "name": "MIRI",
+      "runs-on": "ubuntu-latest",
+      "steps": [
+        {
+          "uses": "actions/checkout@v2",
+          "name": "Checkout"
+        },
+        {
+          "run": "rustup toolchain install nightly --component miri \n
+rustup override set nightly \n
+cargo miri setup",
+          "name": "Install Rust nightly"
+        },
+        {
+          "run": "cargo miri test",
+          "name": "Default features"
+        },
+        {
+          "run": "cargo miri test --no-default-features --features unstable-strict-oom-checks",
+          "name": "Strict OOM check"
+        }
+      ]
+    }
+  }
+}

Cargo.toml

@@ -30,6 +30,9 @@ std = ["alloc", "serde?/std"]
 alloc = ["serde?/alloc"]
 derive = ["bincode_derive"]
 
+# experimental strict OOM checks, requires nightly features
+unstable-strict-oom-checks = ["alloc"]
+
 [dependencies]
 bincode_derive = { path = "derive", version = "2.0.0-rc.3", optional = true }
 serde = { version = "1.0", default-features = false, optional = true }

src/error.rs

@@ -1,5 +1,10 @@
 //! Errors that can be encounting by Encoding and Decoding.
 
+#[cfg(feature = "alloc")]
+use alloc::collections::TryReserveError;
+#[cfg(all(feature = "alloc", feature = "unstable-strict-oom-checks"))]
+use core::alloc::AllocError;
+
 /// Errors that can be encountered by encoding a type
 #[non_exhaustive]
 #[derive(Debug)]
@@ -51,6 +56,10 @@ pub enum EncodeError {
         time: std::boxed::Box<std::time::SystemTime>,
     },
 
+    /// bincode failed to allocate enough memory
+    #[cfg(feature = "alloc")]
+    OutOfMemory(OutOfMemory),
+
     #[cfg(feature = "serde")]
     /// A serde-specific error that occurred while decoding.
     Serde(crate::features::serde::EncodeError),
@@ -188,6 +197,49 @@ pub enum DecodeError {
     #[cfg(feature = "serde")]
     /// A serde-specific error that occurred while decoding.
     Serde(crate::features::serde::DecodeError),
+
+    /// bincode failed to allocate enough memory
+    #[cfg(feature = "alloc")]
+    OutOfMemory(OutOfMemory),
+}
+
+/// A wrapper to make all the out of memory errors consistent
+#[cfg(feature = "alloc")]
+#[derive(Debug)]
+pub enum OutOfMemory {
+    /// Failed to reserve an entry
+    TryReserve(TryReserveError),
+    #[cfg(feature = "unstable-strict-oom-checks")]
+    /// Failed to allocate memory
+    Alloc(AllocError),
+}
+
+#[cfg(feature = "alloc")]
+impl From<TryReserveError> for DecodeError {
+    fn from(e: TryReserveError) -> Self {
+        Self::OutOfMemory(OutOfMemory::TryReserve(e))
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl From<TryReserveError> for EncodeError {
+    fn from(e: TryReserveError) -> Self {
+        Self::OutOfMemory(OutOfMemory::TryReserve(e))
+    }
+}
+
+#[cfg(all(feature = "alloc", feature = "unstable-strict-oom-checks"))]
+impl From<AllocError> for DecodeError {
+    fn from(e: AllocError) -> Self {
+        Self::OutOfMemory(OutOfMemory::Alloc(e))
+    }
+}
+
+#[cfg(all(feature = "alloc", feature = "unstable-strict-oom-checks"))]
+impl From<AllocError> for EncodeError {
+    fn from(e: AllocError) -> Self {
+        Self::OutOfMemory(OutOfMemory::Alloc(e))
+    }
 }
 
 impl core::fmt::Display for DecodeError {