Remove support for self-opening

This was only used for linkage test cases, which is already covered by
the run-make-fulldeps/symbol-visibility test -- which fairly extensively makes
sure we're correctly exporting the right symbols at the right visibility (for
various Rust crate types).

Author: Mark-Simulacrum

src/librustc_interface/util.rs

@@ -205,7 +205,7 @@ pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
 }
 
 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
-    let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
+    let lib = DynamicLibrary::open(path).unwrap_or_else(|err| {
         let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
         early_error(ErrorOutputType::default(), &err);
     });

src/librustc_metadata/creader.rs

@@ -585,7 +585,7 @@ impl<'a> CrateLoader<'a> {
 
         // Make sure the path contains a / or the linker will search for it.
         let path = env::current_dir().unwrap().join(path);
-        let lib = match DynamicLibrary::open(Some(&path)) {
+        let lib = match DynamicLibrary::open(&path) {
             Ok(lib) => lib,
             Err(err) => self.sess.span_fatal(span, &err),
         };

src/librustc_metadata/dynamic_lib.rs

@@ -16,10 +16,9 @@ impl Drop for DynamicLibrary {
 }
 
 impl DynamicLibrary {
-    /// Lazily open a dynamic library. When passed None it gives a
-    /// handle to the calling process
-    pub fn open(filename: Option<&Path>) -> Result<DynamicLibrary, String> {
-        let maybe_library = dl::open(filename.map(|path| path.as_os_str()));
+    /// Lazily open a dynamic library.
+    pub fn open(filename: &Path) -> Result<DynamicLibrary, String> {
+        let maybe_library = dl::open(filename.as_os_str());
 
         // The dynamic library must not be constructed if there is
         // an error opening the library so the destructor does not
@@ -57,24 +56,13 @@ mod dl {
     use std::ptr;
     use std::str;
 
-    pub(super) fn open(filename: Option<&OsStr>) -> Result<*mut u8, String> {
+    pub(super) fn open(filename: &OsStr) -> Result<*mut u8, String> {
         check_for_errors_in(|| unsafe {
-            match filename {
-                Some(filename) => open_external(filename),
-                None => open_internal(),
-            }
+            let s = CString::new(filename.as_bytes()).unwrap();
+            libc::dlopen(s.as_ptr(), libc::RTLD_LAZY) as *mut u8
         })
     }
 
-    unsafe fn open_external(filename: &OsStr) -> *mut u8 {
-        let s = CString::new(filename.as_bytes()).unwrap();
-        libc::dlopen(s.as_ptr(), libc::RTLD_LAZY) as *mut u8
-    }
-
-    unsafe fn open_internal() -> *mut u8 {
-        libc::dlopen(ptr::null(), libc::RTLD_LAZY) as *mut u8
-    }
-
     fn check_for_errors_in<T, F>(f: F) -> Result<T, String>
     where
         F: FnOnce() -> T,
@@ -124,10 +112,10 @@ mod dl {
 
     use winapi::shared::minwindef::HMODULE;
     use winapi::um::errhandlingapi::SetThreadErrorMode;
-    use winapi::um::libloaderapi::{FreeLibrary, GetModuleHandleExW, GetProcAddress, LoadLibraryW};
+    use winapi::um::libloaderapi::{FreeLibrary, GetProcAddress, LoadLibraryW};
     use winapi::um::winbase::SEM_FAILCRITICALERRORS;
 
-    pub(super) fn open(filename: Option<&OsStr>) -> Result<*mut u8, String> {
+    pub(super) fn open(filename: &OsStr) -> Result<*mut u8, String> {
         // disable "dll load failed" error dialog.
         let prev_error_mode = unsafe {
             let new_error_mode = SEM_FAILCRITICALERRORS;
@@ -139,22 +127,9 @@ mod dl {
             prev_error_mode
         };
 
-        let result = match filename {
-            Some(filename) => {
-                let filename_str: Vec<_> = filename.encode_wide().chain(Some(0)).collect();
-                let result = unsafe { LoadLibraryW(filename_str.as_ptr()) } as *mut u8;
-                ptr_result(result)
-            }
-            None => {
-                let mut handle = ptr::null_mut();
-                let succeeded = unsafe { GetModuleHandleExW(0, ptr::null(), &mut handle) };
-                if succeeded == 0 {
-                    Err(io::Error::last_os_error().to_string())
-                } else {
-                    Ok(handle as *mut u8)
-                }
-            }
-        };
+        let filename_str: Vec<_> = filename.encode_wide().chain(Some(0)).collect();
+        let result = unsafe { LoadLibraryW(filename_str.as_ptr()) } as *mut u8;
+        let result = ptr_result(result);
 
         unsafe {
             SetThreadErrorMode(prev_error_mode, ptr::null_mut());

src/librustc_metadata/dynamic_lib/tests.rs

@@ -1,32 +1,4 @@
 use super::*;
-use std::mem;
-
-#[test]
-fn test_loading_atoi() {
-    if cfg!(windows) {
-        return;
-    }
-
-    // The C library does not need to be loaded since it is already linked in
-    let lib = match DynamicLibrary::open(None) {
-        Err(error) => panic!("Could not load self as module: {}", error),
-        Ok(lib) => lib,
-    };
-
-    let atoi: extern "C" fn(*const libc::c_char) -> libc::c_int = unsafe {
-        match lib.symbol("atoi") {
-            Err(error) => panic!("Could not load function atoi: {}", error),
-            Ok(atoi) => mem::transmute::<*mut u8, _>(atoi),
-        }
-    };
-
-    let argument = CString::new("1383428980").unwrap();
-    let expected_result = 0x52757374;
-    let result = atoi(argument.as_ptr());
-    if result != expected_result {
-        panic!("atoi({:?}) != {} but equaled {} instead", argument, expected_result, result)
-    }
-}
 
 #[test]
 fn test_errors_do_not_crash() {
@@ -39,7 +11,7 @@ fn test_errors_do_not_crash() {
     // Open /dev/null as a library to get an error, and make sure
     // that only causes an error, and not a crash.
     let path = Path::new("/dev/null");
-    match DynamicLibrary::open(Some(&path)) {
+    match DynamicLibrary::open(&path) {
         Err(_) => {}
         Ok(_) => panic!("Successfully opened the empty library."),
     }

src/librustc_plugin_impl/load.rs

@@ -76,7 +76,7 @@ fn dylink_registrar(
     // Make sure the path contains a / or the linker will search for it.
     let path = env::current_dir().unwrap().join(&path);
 
-    let lib = match DynamicLibrary::open(Some(&path)) {
+    let lib = match DynamicLibrary::open(&path) {
         Ok(lib) => lib,
         // this is fatal: there are almost certainly macros we need
         // inside this crate, so continue would spew "macro undefined"

src/test/run-make-fulldeps/extern-fn-reachable/main.rs

@@ -8,7 +8,7 @@ use std::path::Path;
 pub fn main() {
     unsafe {
         let path = Path::new("libdylib.so");
-        let a = DynamicLibrary::open(Some(&path)).unwrap();
+        let a = DynamicLibrary::open(&path).unwrap();
         assert!(a.symbol::<isize>("fun1").is_ok());
         assert!(a.symbol::<isize>("fun2").is_ok());
         assert!(a.symbol::<isize>("fun3").is_ok());