Auto merge of #5757 - Eh2406:minimal-versions-build, r=alexcrichton

Minimal versions build

This is a conceptual rebase of #5275, to reiterate:
Big thanks to @klausi for doing most of the work!
Thanks to @matklad for pointing out that we could finish it.

I don't know if I have the Travis config quite correct, advice definitely wellcome!

edit: closes #5275

Author: bors

.travis.yml

@@ -26,6 +26,19 @@ matrix:
            ALT=i686-unknown-linux-gnu
       rust: beta
 
+    # Minimum Rust supported channel. We enable these to make sure we
+    # continue to work on the advertised minimum Rust version.
+    # However cargo only supports the latest stable so this will get
+    # increased every 6 weeks or so when the first PR to use a new feature.
+    - env: TARGET=x86_64-unknown-linux-gnu
+           ALT=i686-unknown-linux-gnu
+      rust: 1.27.2
+      script:
+        - rustup toolchain install nightly
+        - cargo +nightly generate-lockfile -Z minimal-versions
+        - cargo -V
+        - cargo check --tests
+
     - env: TARGET=x86_64-unknown-linux-gnu
            ALT=i686-unknown-linux-gnu
       rust: nightly

Cargo.toml

@@ -21,24 +21,24 @@ atty = "0.2"
 crates-io = { path = "src/crates-io", version = "0.18" }
 crossbeam = "0.3"
 crypto-hash = "0.3.1"
-curl = "0.4.12"
+curl = "0.4.13"
 env_logger = "0.5.4"
 failure = "0.1.1"
 filetime = "0.2"
 flate2 = "1.0"
 fs2 = "0.4"
-git2 = "0.7.0"
+git2 = "0.7.3"
 git2-curl = "0.8.1"
 glob = "0.2.11"
 hex = "0.3"
 home = "0.3"
 ignore = "0.4"
 lazy_static = "1.0.0"
-jobserver = "0.1.9"
+jobserver = "0.1.11"
 lazycell = "1.0"
 libc = "0.2"
-libgit2-sys = "0.7.1"
 log = "0.4"
+libgit2-sys = "0.7.5"
 num_cpus = "1.0"
 rustfix = "0.4"
 same-file = "1"
@@ -64,7 +64,7 @@ num-traits = "0.2" # enable the default feature
 core-foundation = { version = "0.6.0", features = ["mac_os_10_7_support"] }
 
 [target.'cfg(windows)'.dependencies]
-miow = "0.3"
+miow = "0.3.1"
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3"

appveyor.yml

@@ -3,11 +3,16 @@ environment:
   - TARGET: x86_64-pc-windows-msvc
     OTHER_TARGET: i686-pc-windows-msvc
     MAKE_TARGETS: test-unit-x86_64-pc-windows-msvc
+  - TARGET: x86_64-pc-windows-msvc
+    OTHER_TARGET: i686-pc-windows-msvc
+    MAKE_TARGETS: test-unit-x86_64-pc-windows-msvc
+    MINIMAL_VERSIONS: true
 
 install:
   - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
   - rustup-init.exe -y --default-host x86_64-pc-windows-msvc --default-toolchain nightly
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
+  - if defined MINIMAL_VERSIONS rustup toolchain install stable
   - rustup target add %OTHER_TARGET%
   - rustc -V
   - cargo -V
@@ -18,4 +23,5 @@ clone_depth: 1
 build: false
 
 test_script:
-  - cargo test
+  - if defined MINIMAL_VERSIONS cargo +nightly generate-lockfile -Z minimal-versions && cargo +stable check --tests
+  - if NOT defined MINIMAL_VERSIONS cargo test