Add no-std support

.github/workflows/libloading.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust_toolchain: [nightly, stable, 1.71.0]
+        rust_toolchain: [nightly, stable, 1.81.0]
         os: [ubuntu-latest, windows-latest, macOS-latest]
     timeout-minutes: 20
     steps:
@@ -24,15 +24,30 @@ jobs:
       - run: rustup default ${{ matrix.rust_toolchain }}
       - run: rustup component add clippy
       - run: cargo update -p libc --precise 0.2.155
-        if: ${{ matrix.rust_toolchain == '1.71.0' }}
+        if: ${{ matrix.rust_toolchain == '1.81.0' }}
       - run: cargo clippy
       - run: cargo test -- --nocapture
       - run: cargo test --release -- --nocapture
+      - run: cargo test --no-default-features -- --nocapture
+      - run: cargo test --release --no-default-features -- --nocapture
       - run: cargo rustdoc -Zunstable-options --config 'build.rustdocflags=["--cfg", "libloading_docs", "-D", "rustdoc::broken_intra_doc_links"]'
         if: ${{ matrix.rust_toolchain == 'nightly' }}
         # pwsh.exe drops quotes kekw. https://stackoverflow.com/a/59036879
         shell: bash
 
+  no-std-build-test:
+    runs-on: ubuntu-latest
+    # This will rebuild core and alloc, which will re-mangle symbols in alloc,
+    # which then will break the pre-compiled std. This will cause the program to fail to link.
+    # This test does not test anything in an actual no-std environment only that the library compiles on it.
+    # We test all no-std only functions together with the ordinary functions.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Add nightly toolchain
+        run: rustup component add rust-src --toolchain nightly-x86_64-unknown-linux-gnu
+      - name: Compile without the standard library
+        run: cargo clean && cargo +nightly build -Zbuild-std=core,alloc --no-default-features
+
   windows-test:
     runs-on: windows-latest
     strategy:

Cargo.toml

@@ -12,9 +12,13 @@ readme = "README.mkd"
 description = "Bindings around the platform's dynamic library loading primitives with greatly improved memory safety."
 keywords = ["dlopen", "load", "shared", "dylib"]
 categories = ["api-bindings"]
-rust-version = "1.71.0"
+rust-version = "1.81.0"
 edition = "2015"
 
+[features]
+default = ["std"]
+std = []
+
 [target.'cfg(windows)'.dependencies.windows-link]
 version = "0.2"