Don't panic when failing to initialize incremental directory.

2 files changed, 14 insertions, 1 deletions

diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index aa95ecbdaf9..c35a164bb33 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -34,7 +34,7 @@ tempfile = "3.2"
 version = "0.11"
 
 [target.'cfg(windows)'.dependencies]
-winapi = { version = "0.3", features = ["fileapi", "psapi"] }
+winapi = { version = "0.3", features = ["fileapi", "psapi", "winerror"] }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 memmap2 = "0.2.1"
diff --git a/compiler/rustc_data_structures/src/flock.rs b/compiler/rustc_data_structures/src/flock.rs
index 9383be474fd..4f5d8d7ea48 100644
--- a/compiler/rustc_data_structures/src/flock.rs
+++ b/compiler/rustc_data_structures/src/flock.rs
@@ -54,6 +54,10 @@ cfg_if! {
                     Ok(Lock { _file: file })
                 }
             }
+
+            pub fn error_unsupported(err: &io::Error) -> bool {
+                matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+            }
         }
 
         // Note that we don't need a Drop impl to execute `flock(fd, LOCK_UN)`. Lock acquired by
@@ -103,6 +107,10 @@ cfg_if! {
                     Ok(Lock { file })
                 }
             }
+
+            pub fn error_unsupported(err: &io::Error) -> bool {
+                matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+            }
         }
 
         impl Drop for Lock {
@@ -122,6 +130,7 @@ cfg_if! {
         use std::mem;
         use std::os::windows::prelude::*;
 
+        use winapi::shared::winerror::ERROR_INVALID_FUNCTION;
         use winapi::um::minwinbase::{OVERLAPPED, LOCKFILE_FAIL_IMMEDIATELY, LOCKFILE_EXCLUSIVE_LOCK};
         use winapi::um::fileapi::LockFileEx;
         use winapi::um::winnt::{FILE_SHARE_DELETE, FILE_SHARE_READ, FILE_SHARE_WRITE};
@@ -194,6 +203,10 @@ cfg_if! {
                     Ok(Lock { _file: file })
                 }
             }
+
+            pub fn error_unsupported(err: &io::Error) -> bool {
+                err.raw_os_error() == Some(ERROR_INVALID_FUNCTION as i32)
+            }
         }
 
         // Note that we don't need a Drop impl on the Windows: The file is unlocked