Auto merge of #3651 - pkgw:pr-issue-3366, r=alexcrichton

Attempt to solve #3366, regarding spurious shared library search paths.

This drops `native_dirs` entries that are not within the target output when modifying the (DY)LD_LIBRARY_PATH environment variable before running programs.

CC #3366

src/cargo/ops/cargo_rustc/compilation.rs

@@ -20,7 +20,7 @@ pub struct Compilation<'cfg> {
     /// An array of all binaries created.
     pub binaries: Vec<PathBuf>,
 
-    /// All directires for the output of native build commands.
+    /// All directories for the output of native build commands.
     ///
     /// This is currently used to drive some entries which are added to the
     /// LD_LIBRARY_PATH as appropriate.
@@ -104,7 +104,10 @@ impl<'cfg> Compilation<'cfg> {
         } else {
             let mut search_path = vec![];
 
-            // Add -L arguments, after stripping off prefixes like "native=" or "framework=".
+            // Add -L arguments, after stripping off prefixes like "native="
+            // or "framework=" and filtering out directories *not* inside our
+            // output directory, since they are likely spurious and can cause
+            // clashes with system shared libraries (issue #3366).
             for dir in self.native_dirs.iter() {
                 let dir = match dir.to_str() {
                     Some(s) => {
@@ -120,7 +123,10 @@ impl<'cfg> Compilation<'cfg> {
                     }
                     None => dir.clone(),
                 };
-                search_path.push(dir);
+
+                if dir.starts_with(&self.root_output) {
+                    search_path.push(dir);
+                }
             }
             search_path.push(self.root_output.clone());
             search_path.push(self.deps_output.clone());

tests/run.rs

@@ -597,30 +597,37 @@ hello
 
 #[test]
 fn run_with_library_paths() {
-    let p = project("foo")
-        .file("Cargo.toml", r#"
+    let mut p = project("foo");
+
+    // Only link search directories within the target output directory are
+    // propagated through to dylib_path_envvar() (see #3366).
+    let mut dir1 = p.target_debug_dir();
+    dir1.push("foo\\backslash");
+
+    let mut dir2 = p.target_debug_dir();
+    dir2.push("dir=containing=equal=signs");
+
+    p = p.file("Cargo.toml", r#"
             [project]
             name = "foo"
             version = "0.0.1"
             authors = []
             build = "build.rs"
         "#)
-        .file("build.rs", r#"
-            fn main() {
-                println!("cargo:rustc-link-search=native=foo");
-                println!("cargo:rustc-link-search=bar");
-                println!("cargo:rustc-link-search=/path=containing=equal=signs");
-            }
-        "#)
-        .file("src/main.rs", &format!(r#"
+        .file("build.rs", &format!(r##"
+            fn main() {{
+                println!(r#"cargo:rustc-link-search=native={}"#);
+                println!(r#"cargo:rustc-link-search={}"#);
+            }}
+        "##, dir1.display(), dir2.display()))
+        .file("src/main.rs", &format!(r##"
             fn main() {{
                 let search_path = std::env::var_os("{}").unwrap();
                 let paths = std::env::split_paths(&search_path).collect::<Vec<_>>();
-                assert!(paths.contains(&"foo".into()));
-                assert!(paths.contains(&"bar".into()));
-                assert!(paths.contains(&"/path=containing=equal=signs".into()));
+                assert!(paths.contains(&r#"{}"#.into()));
+                assert!(paths.contains(&r#"{}"#.into()));
             }}
-        "#, dylib_path_envvar()));
+        "##, dylib_path_envvar(), dir1.display(), dir2.display()));
 
     assert_that(p.cargo_process("run"), execs().with_status(0));
 }