Increase the MSRV for Corrosion to 1.46

Recently all CI builds using rust 1.44.1 have been failing on CI with the
following error message:
```
error: failed to get `cargo_metadata` as a dependency of package `corrosion-generator v0.1.0 (/home/runner/work/corrosion/corrosion/generator)`

Caused by:
  failed to fetch `https://github.com/rust-lang/crates.io-index`

Caused by:
  error reading from the zlib stream; class=Zlib (5)
CMake Error at cmake/Corrosion.cmake:427 (message):
  corrosion-generator failed: 101
Call Stack (most recent call first):
  test/cpp2rust/CMakeLists.txt:1 (corrosion_import_crate)
  ```

  The relevant issue is probably
  rust-lang/cargo#8258.

Starting with cargo 1.46 the CI failures are resolved

.github/workflows/test.yaml

@@ -34,8 +34,7 @@ jobs:
           - 3.15.7
           - 3.19.0
         rust:
-          - 1.44.1 # Earliest targeted version
-          - 1.45.0 # Earliest version compatible with Windows GNU
+          - 1.46.0 # MSRV Minimum supported rust version
           - stable
           - nightly
         generator:
@@ -82,21 +81,6 @@ jobs:
           - os: macos-12
             abi: gnu
 
-          # Rust
-          # Build each set only with the earliest compatible versioned Rust
-          - os: macos-12
-            rust: 1.45.0
-          - os: ubuntu-latest
-            rust: 1.45.0
-          - os: windows-2019
-            abi: msvc
-            rust: 1.45.0
-          # Prior to 1.45.0, -nostdlib is erroneously passed to g++ when for the *-pc-windows-gnu
-          # target. See: https://github.com/rust-lang/rust/pull/71769
-          - os: windows-2019
-            abi: gnu
-            rust: 1.44.1
-
     steps:
       - name: Determine Rust OS
         id: determine_rust_os
@@ -266,7 +250,7 @@ jobs:
       - name: Install Rust
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.44.1
+          toolchain: 1.46.0
           default: true
       - name: CMake Version
         run: cmake --version

RELEASES.md

@@ -1,10 +1,18 @@
+# Unreleased
+
+# Breaking
+
+- The minimum supported rust version was increased to 1.46. No breaking changes have been added
+  yet, but 1.44.1 is not officially supported anymore, due to an issue with cargo in CI for that
+  version.
+
 # 0.2.1 (2022-05-07)
 
 ## Fixes
 
 - Fix missing variables provided by corrosion, when corrosion is used as a subdirectory ([181](https://github.com/corrosion-rs/corrosion/pull/181)):
   Public [Variables](https://github.com/corrosion-rs/corrosion#information-provided-by-corrosion) set
-  by Corrosion were not visible when using Corrosion as a subdirectory, due to the wrong scope of 
+  by Corrosion were not visible when using Corrosion as a subdirectory, due to the wrong scope of
   the variables. This was fixed by promoting the respective variables to Cache variables.
 
 # 0.2.0 (2022-05-05)
@@ -24,7 +32,7 @@
     `corrosion_set_features()`. See the updated Readme for details.
   - `CORROSION_ENVIRONMENT_VARIABLES`. Please use `corrosion_set_env_vars()` instead.
   - `CORROSION_USE_HOST_BUILD`. Please use `corrosion_set_hostbuild()` instead.
-- The Minimum CMake version will likely be increased for the next major release. At the very least we want to drop 
+- The Minimum CMake version will likely be increased for the next major release. At the very least we want to drop
   support for CMake 3.12, but requiring CMake 3.16 or even 3.18 is also on the table. If you are using a CMake version
   that would be no longer supported by corrosion, please comment on issue
   [#168](https://github.com/corrosion-rs/corrosion/issues/168), so that we can gauge the number of affected users.
@@ -33,7 +41,7 @@
 
 - Add `NO_STD` option to `corrosion_import_crate` ([#154](https://github.com/corrosion-rs/corrosion/pull/154)).
 - Remove the requirement of building the Rust based generator crate for CMake >= 3.19. This makes using corrosion as
-  a subdirectory as fast as the installed version (since everything is done in CMake). 
+  a subdirectory as fast as the installed version (since everything is done in CMake).
   ([#131](https://github.com/corrosion-rs/corrosion/pull/131), [#161](https://github.com/corrosion-rs/corrosion/pull/161))
   If you do choose to install Corrosion, then by default the old Generator is still compiled and installed, so you can
   fall back to using it in case you use multiple cmake versions on the same machine for different projects.
@@ -44,13 +52,13 @@
   [#164](https://github.com/corrosion-rs/corrosion/pull/164)).
 - Improve robustness of parsing the LLVM version (exported in `Rust_LLVM_VERSION`). It now also works for
   Rust versions, where the LLVM version is reported as `MAJOR.MINOR`. ([#148](https://github.com/corrosion-rs/corrosion/pull/148))
-- Fix a bug which occurred when Corrosion was added multiple times via `add_subdirectory()` 
+- Fix a bug which occurred when Corrosion was added multiple times via `add_subdirectory()`
   ([#143](https://github.com/corrosion-rs/corrosion/pull/143)).
-- Set `CC_<target_triple_undercore>` and `CXX_<target_triple_undercore>` environment variables for the invocation of 
-  `cargo build` to the compilers selected by CMake  (if any) 
+- Set `CC_<target_triple_undercore>` and `CXX_<target_triple_undercore>` environment variables for the invocation of
+  `cargo build` to the compilers selected by CMake  (if any)
   ([#138](https://github.com/corrosion-rs/corrosion/pull/138) and [#161](https://github.com/corrosion-rs/corrosion/pull/161)).
   This should ensure that C dependencies built in cargo buildscripts via [cc-rs](https://github.com/alexcrichton/cc-rs)
-  use the same compiler as CMake built dependencies. Users can override the compiler by specifying the higher 
+  use the same compiler as CMake built dependencies. Users can override the compiler by specifying the higher
   priority environment variable variants with dashes instead of underscores (See cc-rs documentation for details).
 - Fix Ninja-Multiconfig Generator support for CMake versions >= 3.20. Previous CMake versions are missing a feature,
   which prevents us from supporting the Ninja-Multiconfig generator. ([#137](https://github.com/corrosion-rs/corrosion/pull/137))
@@ -64,7 +72,7 @@ September 2021.
 
 ## New features
 - [Add --profile support for rust >= 1.57](https://github.com/corrosion-rs/corrosion/pull/130):
-  Allows users to specify a custom cargo profile with 
+  Allows users to specify a custom cargo profile with
   `corrosion_import_crate(... PROFILE <profilename>)`.
 - [Add support for specifying per-target Rustflags](https://github.com/corrosion-rs/corrosion/pull/127):
   Rustflags can be added via `corrosion_add_target_rustflags(<target_name> [rustflags1...])`