Fix support for MSRV

.github/workflows/ci.yml

@@ -78,12 +78,14 @@ jobs:
           toolchain: ${{ matrix.rust }}
           target: ${{ matrix.platform.rust-target }}
           profile: minimal
+          default: true
 
       - if: matrix.platform.os == 'ubuntu-latest'
         name: Prepare LD_LIBRARY_PATH (Ubuntu only)
         run: echo LD_LIBRARY_PATH=${pythonLocation}/lib > $GITHUB_ENV
 
-      - run: rustup set default-host ${{ matrix.platform.rust-target }}
+      - name: Prepare CARGO_BUILD_TARGET
+        run: echo CARGO_BUILD_TARGET=${{ matrix.platform.rust-target }} > $GITHUB_ENV
 
       - name: Build without default features
         run: cargo build --no-default-features --verbose

CHANGELOG.md

@@ -5,6 +5,10 @@ PyO3 versions, please see the [migration guide](https://pyo3.rs/master/migration
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- Fix support for Rust versions 1.39 to 1.44, broken by an incorrect internal update to paste 1.0 which was done in PyO3 0.12.2. [#1234](https://github.com/PyO3/pyo3/pull/1234)
+
 ## [0.12.2] - 2020-10-12
 ### Added
 - Add support for keyword-only arguments without default values in `#[pyfunction]`. [#1209](https://github.com/PyO3/pyo3/pull/1209)

Cargo.toml

@@ -22,7 +22,7 @@ libc = "0.2.62"
 parking_lot = "0.11.0"
 num-bigint = { version = "0.3", optional = true }
 num-complex = { version = "0.3", optional = true }
-paste = { version = "1.0.1", optional = true }
+paste = { version = "0.1.6", optional = true }
 pyo3cls = { path = "pyo3cls", version = "=0.12.2", optional = true }
 unindent = { version = "0.1.4", optional = true }
 hashbrown = { version = "0.9", optional = true }