Experiment with version ranges, -Zminimal-versions

This commit uses version ranges to accurately specify the minimum
version of the dependencies required for this library to work. These
version bounds are verified in the CI with `-Zminimal-versions`
functionality of cargo which forces cargo to select the earliest
versions of libraries possible.

Author: nagisa

.github/workflows/libloading.yml

@@ -1,10 +1,12 @@
-name: Test libloading
+name: libloading
 
 on:
   push:
     paths-ignore:
     - '*.mkd'
     - 'LICENSE'
+    branches:
+    - master
   pull_request:
     types: [opened, repoened, synchronize]
 
@@ -19,6 +21,8 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v2
+      - name: Set cfg(ci)
+        run: echo "RUSTFLAGS=--cfg ci" >> $GITHUB_ENV
       - name: Install Rust ${{ matrix.rust_toolchain }}
         uses: actions-rs/toolchain@v1
         with:
@@ -58,6 +62,18 @@ jobs:
         env:
           RUSTDOCFLAGS: --cfg docsrs
         if: ${{ matrix.rust_toolchain == 'nightly' }}
+      - name: Update Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: update
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
+        if: ${{ matrix.rust_toolchain == 'nightly' }}
+      - name: Test Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options -- --nocapture
+        if: ${{ matrix.rust_toolchain == 'nightly' }}
 
   windows-gnu-test:
     runs-on: windows-latest
@@ -70,6 +86,8 @@ jobs:
           - i686-pc-windows-gnu
     steps:
       - uses: actions/checkout@v2
+      - name: Set cfg(ci)
+        run: echo "RUSTFLAGS=--cfg ci" >> $GITHUB_ENV
       - name: Add MSYS2 to the PATH
         run: echo "c:/msys64/bin" | Out-File -FilePath $env:GITHUB_PATH -Append
       - name: Add 32-bit mingw-w64 to the PATH
@@ -78,7 +96,7 @@ jobs:
       - name: Add 64-bit mingw-w64 to the PATH
         run: echo "c:/msys64/mingw64/bin" | Out-File -FilePath $env:GITHUB_PATH -Append
         if: startsWith(matrix.rust_target, 'x86_64')
-      - name: Set TARGET variable
+      - name: Set $TARGET
         run: echo "TARGET=${{ matrix.rust_target}}" | Out-File -FilePath $env:GITHUB_ENV -Append
       - name: Install Rust nightly
         uses: actions-rs/toolchain@v1
@@ -87,32 +105,59 @@ jobs:
             target: ${{ matrix.rust_target }}
             profile: minimal
             default: true
-      - uses: actions-rs/cargo@v1
+      - name: Update
+        uses: actions-rs/cargo@v1
         with:
-          command: build
-          args: --target ${{ matrix.rust_target }} --manifest-path=Cargo.toml
+          command: update
+          args: --manifest-path=Cargo.toml
       - uses: actions-rs/cargo@v1
         with:
           command: test
           args: --target ${{ matrix.rust_target }} --manifest-path=Cargo.toml
+      - name: Update Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: update
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
+        if: ${{ matrix.rust_toolchain == 'nightly' }}
+      - name: Test Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --target ${{ matrix.rust_target }} --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options -- --nocapture
+        if: ${{ matrix.rust_toolchain == 'nightly' }}
 
   bare-cross-build:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
         rust_target:
-          # BSDs: could be tested with full system emulation
-          # - x86_64-unknown-dragonfly
-          # - x86_64-unknown-freebsd
+          - aarch64-unknown-linux-gnu
+          - arm-unknown-linux-gnueabihf
+          - mips64-unknown-linux-gnuabi64
+          - mips-unknown-linux-gnu
+          - powerpc64le-unknown-linux-gnu
+          - powerpc64-unknown-linux-gnu
+          - powerpc-unknown-linux-gnu
+          - riscv64gc-unknown-linux-gnu
+          - s390x-unknown-linux-gnu
+          - sparc64-unknown-linux-gnu
+          - sparcv9-sun-solaris
+          - x86_64-fuchsia
+          - x86_64-unknown-dragonfly
+          - x86_64-unknown-freebsd
           - x86_64-unknown-haiku
-          # - x86_64-unknown-netbsd
+          - x86_64-unknown-netbsd
           - x86_64-unknown-openbsd
           - x86_64-unknown-redox
-          - x86_64-fuchsia
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v2
+      - name: Set cfg(ci)
+        run: echo "RUSTFLAGS=--cfg ci" >> $GITHUB_ENV
+      - name: Set $TARGET
+        run: echo "TARGET=${{ matrix.rust_target}}" >> $GITHUB_ENV
       - name: Install Rust nightly
         uses: actions-rs/toolchain@v1
         with:
@@ -132,6 +177,16 @@ jobs:
         with:
           command: build
           args: --target ${{ matrix.rust_target }} --manifest-path=Cargo.toml -Zbuild-std
+      - name: Update Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: update
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
+      - name: Build Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
 
   cross-ios-build:
     runs-on: macos-latest
@@ -145,6 +200,10 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v2
+      - name: Set cfg(ci)
+        run: echo "RUSTFLAGS=--cfg ci" >> $GITHUB_ENV
+      - name: Set $TARGET
+        run: echo "TARGET=${{ matrix.rust_target}}" >> $GITHUB_ENV
       - name: Install Rust ${{ matrix.rust_toolchain }}
         uses: actions-rs/toolchain@v1
         with:
@@ -162,3 +221,15 @@ jobs:
         with:
           command: build
           args: --target=${{ matrix.rust_target }} --manifest-path=Cargo.toml
+      - name: Update Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: update
+          args: --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
+        if: ${{ matrix.rust_toolchain == 'nightly' }}
+      - name: Build Minimal Versions
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --target=${{ matrix.rust_target }} --manifest-path=Cargo.toml -Zminimal-versions -Zunstable-options
+        if: ${{ matrix.rust_toolchain == 'nightly' }}

Cargo.toml

@@ -14,19 +14,20 @@ keywords = ["dlopen", "load", "shared", "dylib"]
 categories = ["api-bindings"]
 
 [target.'cfg(windows)'.dependencies.winapi]
-version = "0.3"
+version = ">=0.3.0, <0.4"
 features = [
     "winerror",
     "errhandlingapi",
     "libloaderapi",
 ]
 
 [target.'cfg(unix)'.dependencies.cfg-if]
-version = "1"
+version = ">=0.1.10, <2"
 
-[dev-dependencies]
-libc = "0.2"
-static_assertions = "1.1"
+# We make some more rigorous checks in CI
+[target.'cfg(ci)'.dependencies]
+libc = ">=0.2.7, <0.3"
+static_assertions = ">=1.0.0, <2"
 
 [package.metadata.docs.rs]
 all-features = true

src/os/unix/consts.rs

@@ -203,6 +203,19 @@ mod posix {
     }
 }
 
+#[cfg(ci)]
+mod verify_consts {
+    extern crate static_assertions;
+    extern crate libc;
+    use self::static_assertions::*;
+
+    const_assert_eq!(false, true);
+    const_assert_eq!(super::RTLD_LOCAL, libc::RTLD_LOCAL);
+    const_assert_eq!(super::RTLD_GLOBAL, libc::RTLD_GLOBAL);
+    const_assert_eq!(super::RTLD_NOW, libc::RTLD_NOW);
+    const_assert_eq!(super::RTLD_LAZY, libc::RTLD_LAZY);
+}
+
 // Other constants that exist but are not bound because they are platform-specific (non-posix)
 // extensions. Some of these constants are only relevant to `dlsym` or `dlmopen` calls.
 //

tests/constants.rs

@@ -20,6 +20,7 @@ fn make_helpers() {
         } else {
             eprintln!("WARNING: $TARGET NOT SPECIFIED! BUILDING HELPER MODULE FOR NATIVE TARGET.");
         }
+        eprintln!("Building helper: {:?}", cmd);
         assert!(cmd
             .status()
             .expect("could not compile the test helpers!")