Use thiserror instead of snafu in std

Author: webmaster128

CHANGELOG.md

@@ -7,6 +7,11 @@
 - Remove the previously deprecated `StdError::Unauthorized`. Contract specific
   errors should be implemented using custom error types now (see
   [migration guide](./MIGRATING.md) 0.10 -> 0.11).
+- Use dependency `thiserror` instead of `snafu` to implement `StdError`. Along
+  with this change, the `backtraces` feature now requires Rust nightly.
+- Rename `StdError::ParseErr::source` to `StdError::ParseErr::source_type` and
+  `StdError::SerializeErr::target` to `StdError::SerializeErr::target_type` to
+  work around speacial treatment of the field name `source` in thiserror.
 
 **cosmwasm-vm**
 

Cargo.lock

@@ -4,6 +4,25 @@ This guide explains what is needed to upgrade contracts when migrating over
 major releases of `cosmwasm`. Note that you can also view the
 [complete CHANGELOG](./CHANGELOG.md) to understand the differences.
 
+## 0.11 -> 0.12
+
+- In your contract's `.cargo/config` remove `--features backtraces`, which is
+  now available in Rust nightly only:
+
+  ```diff
+  @@ -1,6 +1,6 @@
+   [alias]
+   wasm = "build --release --target wasm32-unknown-unknown"
+   wasm-debug = "build --target wasm32-unknown-unknown"
+  -unit-test = "test --lib --features backtraces"
+  +unit-test = "test --lib"
+   integration-test = "test --test integration"
+   schema = "run --example schema"
+  ```
+
+  In order to use backtraces for debugging, run
+  `RUST_BACKTRACE=1 cargo +nightly unit-test --features backtraces`.
+
 ## 0.10 -> 0.11
 
 - Contracts now support any custom error type `E: ToString + From<StdError>`.

MIGRATING.md

@@ -1,6 +1,6 @@
 [alias]
 wasm = "build --release --target wasm32-unknown-unknown"
 wasm-debug = "build --target wasm32-unknown-unknown"
-unit-test = "test --lib --features backtraces"
+unit-test = "test --lib"
 integration-test = "test --test integration"
 schema = "run --example schema"

contracts/burner/.cargo/config

@@ -1,6 +1,6 @@
 [alias]
 wasm = "build --release --target wasm32-unknown-unknown"
 wasm-debug = "build --target wasm32-unknown-unknown"
-unit-test = "test --lib --features backtraces"
+unit-test = "test --lib"
 integration-test = "test --test integration"
 schema = "run --example schema"

contracts/burner/Cargo.lock

@@ -1,6 +1,6 @@
 [alias]
 wasm = "build --release --target wasm32-unknown-unknown"
 wasm-debug = "build --target wasm32-unknown-unknown"
-unit-test = "test --lib --features backtraces"
+unit-test = "test --lib"
 integration-test = "test --test integration"
 schema = "run --example schema"

contracts/hackatom/.cargo/config

@@ -1,6 +1,6 @@
 [alias]
 wasm = "build --release --target wasm32-unknown-unknown"
 wasm-debug = "build --target wasm32-unknown-unknown"
-unit-test = "test --lib --features backtraces"
+unit-test = "test --lib"
 integration-test = "test --test integration"
 schema = "run --example schema"