From 3a92401847b682dc9c8c907b501bd33fb6f257bc Mon Sep 17 00:00:00 2001
From: Raekye <Raekye@users.noreply.github.com>
Date: Wed, 4 Oct 2023 03:56:34 -0400
Subject: [PATCH] Found cause - rust-lang/rust#47384?

---
 README.md                       | 31 +++++++++++++++++++++++++++++++
 build.rs                        |  3 ---
 src/bin/main.rs                 |  6 ------
 src/bin/with_extern_crate.rs    |  5 +++++
 src/bin/without_extern_crate.rs |  3 +++
 5 files changed, 39 insertions(+), 9 deletions(-)
 create mode 100644 README.md
 delete mode 100644 build.rs
 delete mode 100644 src/bin/main.rs
 create mode 100644 src/bin/with_extern_crate.rs
 create mode 100644 src/bin/without_extern_crate.rs

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..dfc2b60
--- /dev/null
+++ b/README.md
@@ -0,0 +1,31 @@
+Functions from the library crate marked `#[no_mangle]` seem to be removed from executables if no references are made to the library,
+even when a linker arg like `-rdynamic` is used.
+This behaviour seems to be described in this bug report: https://github.com/rust-lang/rust/issues/47384.
+However, that bug report is supposedly fixed by https://github.com/rust-lang/rust/pull/95604.
+
+```
+# cat src/bin/without_extern_crate.rs
+fn main() {
+	println!("Hello, world!");
+}
+```
+
+```
+# RUSTFLAGS='-C link-arg=-rdynamic' cargo build && nm -g target/debug/without_extern_crate.rs | grep foo
+# nothing
+```
+
+```
+# cat src/bin/with_extern_crate.rs
+extern crate export_symbols;
+
+fn main() {
+	println!("Hello, world!");
+}
+```
+
+```
+# RUSTFLAGS='-C link-arg=-rdynamic' cargo build && nm -g target/debug/with_extern_crate.rs | grep foo
+000000000006dfa0 T foo1
+000000000006dfb0 T foo2
+```
diff --git a/build.rs b/build.rs
deleted file mode 100644
index a97f60a..0000000
--- a/build.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-fn main() {
-	println!("cargo:rustc-link-arg-bins=-rdynamic");
-}
diff --git a/src/bin/main.rs b/src/bin/main.rs
deleted file mode 100644
index e11cac9..0000000
--- a/src/bin/main.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-fn main() {
-	// Without referencing foo2, it won't show up in the final executable (neither will foo1).
-	// By referencing foo2, foo1 also shows up, even though nothing references it?
-	let _ = export_symbols::foo2;
-	println!("Hello, world!");
-}
diff --git a/src/bin/with_extern_crate.rs b/src/bin/with_extern_crate.rs
new file mode 100644
index 0000000..d02f14c
--- /dev/null
+++ b/src/bin/with_extern_crate.rs
@@ -0,0 +1,5 @@
+extern crate export_symbols;
+
+fn main() {
+	println!("Hello, world!");
+}
diff --git a/src/bin/without_extern_crate.rs b/src/bin/without_extern_crate.rs
new file mode 100644
index 0000000..a30eb95
--- /dev/null
+++ b/src/bin/without_extern_crate.rs
@@ -0,0 +1,3 @@
+fn main() {
+	println!("Hello, world!");
+}