Add a test that dynamically loaded libraries symbolicate (#332)

Author: alexcrichton

Cargo.toml

@@ -48,6 +48,10 @@ features = ['read_core', 'elf', 'macho', 'pe']
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3.3", optional = true }
 
+[dev-dependencies]
+dylib-dep = { path = "crates/dylib-dep" }
+libloading = "0.6"
+
 [features]
 # By default libstd support and gimli-symbolize is used to symbolize addresses.
 default = ["std", "gimli-symbolize"]
@@ -131,7 +135,7 @@ edition = '2018'
 
 [[test]]
 name = "accuracy"
-required-features = ["std", "libbacktrace"]
+required-features = ["std", "gimli-symbolize"]
 edition = '2018'
 
 [[test]]

crates/dylib-dep/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "dylib-dep"
+version = "0.1.0"
+edition = "2018"
+authors = []
+publish = false
+
+[lib]
+name = "dylib_dep"
+crate-type = ["cdylib", "rlib"]

crates/dylib-dep/src/lib.rs

@@ -0,0 +1,12 @@
+type Pos = (&'static str, u32);
+
+macro_rules! pos {
+    () => {
+        (file!(), line!())
+    };
+}
+
+#[no_mangle]
+pub extern "C" fn foo(outer: Pos, inner: fn(Pos, Pos)) {
+    inner(outer, pos!());
+}

tests/accuracy/main.rs

@@ -16,6 +16,29 @@ type Pos = (&'static str, u32);
 
 #[test]
 fn doit() {
+    // Skip musl which is by default statically linked and doesn't support
+    // dynamic libraries.
+    //
+    // FIXME(#333) doesn't work on MinGW yet
+    if !cfg!(target_env = "musl") && !(cfg!(windows) && cfg!(target_env = "gnu")) {
+        // TODO(#238) this shouldn't have to happen first in this function, but
+        // currently it does.
+        let mut dir = std::env::current_exe().unwrap();
+        dir.pop();
+        if cfg!(windows) {
+            dir.push("dylib_dep.dll");
+        } else if cfg!(target_os = "macos") {
+            dir.push("libdylib_dep.dylib");
+        } else {
+            dir.push("libdylib_dep.so");
+        }
+        let lib = libloading::Library::new(&dir).unwrap();
+        let api = unsafe { lib.get::<extern "C" fn(Pos, fn(Pos, Pos))>(b"foo").unwrap() };
+        api(pos!(), |a, b| {
+            check!(a, b);
+        });
+    }
+
     outer(pos!());
 }