chore: increase MSRV to 1.49. (#4457)

Rust 1.49 was released on December 31, 2020, which meets our MSRV policy
of a minimum of 6 months.

Author: carllerche

.clippy.toml

@@ -1 +1 @@
-msrv = "1.46"
+msrv = "1.49"

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ env:
   rust_stable: stable
   rust_nightly: nightly-2022-01-12
   rust_clippy: 1.52.0
-  rust_min: 1.46.0
+  rust_min: 1.49.0
 
 defaults:
   run:

README.md

@@ -163,9 +163,9 @@ several other libraries, including:
 
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version
-is 1.46.  The current Tokio version is not guaranteed to build on Rust versions
-earlier than the minimum supported version.
+Tokio will keep a rolling MSRV (minimum supported rust version) policy of **at
+least** 6 months. When increasing the MSRV, the new Rust version must have been
+released at least six months ago. The current MSRV is 1.49.0.
 
 ## Release schedule
 

tokio-macros/Cargo.toml

@@ -6,7 +6,7 @@ name = "tokio-macros"
 # - Create "tokio-macros-1.0.x" git tag.
 version = "1.7.0"
 edition = "2018"
-rust-version = "1.46"
+rust-version = "1.49"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"

tokio-stream/Cargo.toml

@@ -6,7 +6,7 @@ name = "tokio-stream"
 # - Create "tokio-stream-0.1.x" git tag.
 version = "0.1.8"
 edition = "2018"
-rust-version = "1.46"
+rust-version = "1.49"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"

tokio-test/Cargo.toml

@@ -6,7 +6,7 @@ name = "tokio-test"
 # - Create "tokio-test-0.4.x" git tag.
 version = "0.4.2"
 edition = "2018"
-rust-version = "1.46"
+rust-version = "1.49"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"

tokio-util/Cargo.toml

@@ -6,7 +6,7 @@ name = "tokio-util"
 # - Create "tokio-util-0.7.x" git tag.
 version = "0.7.0"
 edition = "2018"
-rust-version = "1.46"
+rust-version = "1.49"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"

tokio/Cargo.toml

@@ -8,7 +8,7 @@ name = "tokio"
 # - Create "v1.0.x" git tag.
 version = "1.16.1"
 edition = "2018"
-rust-version = "1.46"
+rust-version = "1.49"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 readme = "README.md"

tokio/README.md

@@ -163,9 +163,9 @@ several other libraries, including:
 
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version
-is 1.46.  The current Tokio version is not guaranteed to build on Rust versions
-earlier than the minimum supported version.
+Tokio will keep a rolling MSRV (minimum supported rust version) policy of **at
+least** 6 months. When increasing the MSRV, the new Rust version must have been
+released at least six months ago. The current MSRV is 1.49.0.
 
 ## Release schedule