std::dynamic_lib: Fix Windows error handling

This is a [breaking-change] since `std::dynamic_lib::dl` is now
private.

When `LoadLibraryW()` fails, original code called `errno()` to get error
code.  However, there was local allocation of `Vec` before
`LoadLibraryW()`, and it drops before `errno()`, and the drop
(deallocation) changed `errno`! Therefore `dynamic_lib::open()` thought
it always succeeded.
This commit fixes the issue.

This commit also sets Windows error mode during `LoadLibrary()` to
prevent "dll load failed" dialog.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index 37ed32fa367..da3b7ee2f2f 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -226,6 +226,7 @@ pub mod compat {
     /// * `CreateSymbolicLinkW`: Windows XP, Windows Server 2003
     /// * `GetFinalPathNameByHandleW`: Windows XP, Windows Server 2003
     pub mod kernel32 {
+        use libc::c_uint;
         use libc::types::os::arch::extra::{DWORD, LPCWSTR, BOOLEAN, HANDLE};
         use libc::consts::os::extra::ERROR_CALL_NOT_IMPLEMENTED;
 
@@ -249,6 +250,12 @@ pub mod compat {
                 unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0 }
             }
         }
+
+        compat_fn! {
+            kernel32::SetThreadErrorMode(_dwNewMode: DWORD, _lpOldMode: *mut DWORD) -> c_uint {
+                unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0 }
+            }
+        }
     }
 }