Test for static linking failure

Cargo.toml

@@ -1,3 +1,7 @@
 [workspace]
-members = [ "ctor", "codegen", "dtor", "tests", "tests-wasm" ]
+members = [ "ctor", "codegen", "dtor", "tests", "tests-wasm", "tests-static", "tests-static-main" ]
 resolver = "2"
+
+
+[profile.dev]
+codegen-units = 1

README.md

@@ -4,7 +4,9 @@
 [![docs.rs](https://docs.rs/ctor/badge.svg)](https://docs.rs/ctor)
 [![crates.io](https://img.shields.io/crates/v/ctor.svg)](https://crates.io/crates/ctor)
 
-Module initialization/teardown functions for Rust (like `__attribute__((constructor))` in C/C++) for Linux, OSX, FreeBSD, NetBSD, Illumos, OpenBSD, DragonFlyBSD, Android, iOS, and Windows.
+Module initialization/teardown functions for Rust (like
+`__attribute__((constructor))` in C/C++) for Linux, OSX, FreeBSD, NetBSD,
+Illumos, OpenBSD, DragonFlyBSD, Android, iOS, WASM, and Windows.
 
 This library currently requires **Rust > 1.31.0** at a minimum for the
 procedural macro support.
@@ -25,6 +27,18 @@ startup/shutdown respectively.
 This library supports WASM targets, but note that only a single `#[ctor]` function is
 supported due to platform limitations.
 
+## Linking
+
+The `#[ctor]` and `#[dtor]` macros make use of linker sections to ensure that a
+function is run at startup time.
+
+Because of various platform linking issues, you may need to ensure that you
+reference a symbol in each module that provides a `#[ctor]` or `#[dtor]`. If the
+functions do not run as expected, `use other_crate` may be sufficient to fix
+things.
+
+See https://github.com/rust-lang/rust/issues/133491 for more information.
+
 ## Warnings
 
 Rust's philosophy is that nothing happens before or after main and

tests-static-main/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "tests-static-main"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[features]
+import = []
+used_linker = ["ctor/used_linker", "tests-static/used_linker"]
+
+[dependencies]
+ctor = { path = "../ctor" }
+libc-print = "0.1.15"
+tests-static = { path = "../tests-static" }

tests-static-main/README.md

@@ -0,0 +1,16 @@
+# Static linking example
+
+Example showing how static linking may be complicated. Without the `import` feature,
+the `#[ctor]` function will not be run.
+
+```
+cargo run -p tests-static-main --features=import
+```
+
+On MacOS, you may need to link with `rust-lld`:
+
+```
+RUSTFLAGS="-Clinker=rust-lld" cargo run -p tests-static-main --features=import
+```
+
+See https://github.com/rust-lang/rust/issues/133491 for more information.

tests-static-main/src/main.rs

@@ -0,0 +1,5 @@
+#[allow(unused)]
+#[cfg(feature = "import")]
+use tests_static;
+
+fn main() {}

tests-static/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "tests-static"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[features]
+used_linker = ["ctor/used_linker"]
+
+[lib]
+
+[dependencies]
+ctor = { path = "../ctor" }
+libc-print = "0.1.15"

tests-static/src/lib.rs

@@ -0,0 +1,6 @@
+#![cfg_attr(feature = "used_linker", feature(used_with_arg))]
+
+#[ctor::ctor]
+pub fn foo() {
+    libc_print::libc_println!("foo");
+}

tests-wasm/src/lib.rs

@@ -1,4 +1,4 @@
-#[cfg(target_family="wasm")]
+#[cfg(target_family = "wasm")]
 #[ctor::ctor]
 unsafe fn hello() {
     use wasm_bindgen::prelude::wasm_bindgen;

tests/Cargo.toml

@@ -21,4 +21,4 @@ crate-type = ["cdylib"]
 
 [[example]]
 name = "dylib_load"
-path = "src/dylib_load.rs"
+path = "src/dylib_load.rs"