Originally, when the Rust upstream `alloc` standard library crate was
vendored in commit 057b8d257107 ("rust: adapt `alloc` crate to the
kernel"), the SPDX License Identifiers were added to every file so that
the license on those was clear.

Thus do the same for the `proc-macro2` crate.

This makes `scripts/spdxcheck.py` pass.

Reviewed-by: Gary Guo <gary@garyguo.net>
Tested-by: Gary Guo <gary@garyguo.net>
Tested-by: Jesung Yang <y.j3ms.n@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/proc-macro2/detection.rs                      | 2 ++
 rust/proc-macro2/extra.rs                          | 2 ++
 rust/proc-macro2/fallback.rs                       | 2 ++
 rust/proc-macro2/lib.rs                            | 2 ++
 rust/proc-macro2/location.rs                       | 2 ++
 rust/proc-macro2/marker.rs                         | 2 ++
 rust/proc-macro2/parse.rs                          | 2 ++
 rust/proc-macro2/probe.rs                          | 2 ++
 rust/proc-macro2/probe/proc_macro_span.rs          | 2 ++
 rust/proc-macro2/probe/proc_macro_span_file.rs     | 2 ++
 rust/proc-macro2/probe/proc_macro_span_location.rs | 2 ++
 rust/proc-macro2/rcvec.rs                          | 2 ++
 rust/proc-macro2/wrapper.rs                        | 2 ++
 13 files changed, 26 insertions(+)

diff --git a/rust/proc-macro2/detection.rs b/rust/proc-macro2/detection.rs
index beba7b237395..3de448cb2dde 100644
--- a/rust/proc-macro2/detection.rs
+++ b/rust/proc-macro2/detection.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use core::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Once;
 
diff --git a/rust/proc-macro2/extra.rs b/rust/proc-macro2/extra.rs
index 522a90e136be..55feb5ec7526 100644
--- a/rust/proc-macro2/extra.rs
+++ b/rust/proc-macro2/extra.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 //! Items which do not have a correspondence to any API in the proc_macro crate,
 //! but are necessary to include in proc-macro2.
 
diff --git a/rust/proc-macro2/fallback.rs b/rust/proc-macro2/fallback.rs
index 1560105cfd25..9e005d67f7f5 100644
--- a/rust/proc-macro2/fallback.rs
+++ b/rust/proc-macro2/fallback.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 #[cfg(wrap_proc_macro)]
 use crate::imp;
 #[cfg(span_locations)]
diff --git a/rust/proc-macro2/lib.rs b/rust/proc-macro2/lib.rs
index 2984af335adc..7b78d065d51c 100644
--- a/rust/proc-macro2/lib.rs
+++ b/rust/proc-macro2/lib.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 //! [![github]](https://github.com/dtolnay/proc-macro2)&ensp;[![crates-io]](https://crates.io/crates/proc-macro2)&ensp;[![docs-rs]](crate)
 //!
 //! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
diff --git a/rust/proc-macro2/location.rs b/rust/proc-macro2/location.rs
index 7190e2d05255..3a11871e2943 100644
--- a/rust/proc-macro2/location.rs
+++ b/rust/proc-macro2/location.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use core::cmp::Ordering;
 
 /// A line-column pair representing the start or end of a `Span`.
diff --git a/rust/proc-macro2/marker.rs b/rust/proc-macro2/marker.rs
index 23b94ce6fa85..6f322424808c 100644
--- a/rust/proc-macro2/marker.rs
+++ b/rust/proc-macro2/marker.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use alloc::rc::Rc;
 use core::marker::PhantomData;
 use core::panic::{RefUnwindSafe, UnwindSafe};
diff --git a/rust/proc-macro2/parse.rs b/rust/proc-macro2/parse.rs
index b8be403f842f..a005dea1fe88 100644
--- a/rust/proc-macro2/parse.rs
+++ b/rust/proc-macro2/parse.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use crate::fallback::{
     self, is_ident_continue, is_ident_start, Group, Ident, LexError, Literal, Span, TokenStream,
     TokenStreamBuilder,
diff --git a/rust/proc-macro2/probe.rs b/rust/proc-macro2/probe.rs
index b67f52036218..d68aa8cfd85e 100644
--- a/rust/proc-macro2/probe.rs
+++ b/rust/proc-macro2/probe.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 #![allow(dead_code)]
 
 #[cfg(proc_macro_span)]
diff --git a/rust/proc-macro2/probe/proc_macro_span.rs b/rust/proc-macro2/probe/proc_macro_span.rs
index 2d7d44e07708..892a7eb3e5a0 100644
--- a/rust/proc-macro2/probe/proc_macro_span.rs
+++ b/rust/proc-macro2/probe/proc_macro_span.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 // This code exercises the surface area that we expect of Span's unstable API.
 // If the current toolchain is able to compile it, then proc-macro2 is able to
 // offer these APIs too.
diff --git a/rust/proc-macro2/probe/proc_macro_span_file.rs b/rust/proc-macro2/probe/proc_macro_span_file.rs
index 8b76bdf5007b..f2dbc4056ebe 100644
--- a/rust/proc-macro2/probe/proc_macro_span_file.rs
+++ b/rust/proc-macro2/probe/proc_macro_span_file.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 // The subset of Span's API stabilized in Rust 1.88.
 
 extern crate proc_macro;
diff --git a/rust/proc-macro2/probe/proc_macro_span_location.rs b/rust/proc-macro2/probe/proc_macro_span_location.rs
index 79da34af54af..ae19c93394fa 100644
--- a/rust/proc-macro2/probe/proc_macro_span_location.rs
+++ b/rust/proc-macro2/probe/proc_macro_span_location.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 // The subset of Span's API stabilized in Rust 1.88.
 
 extern crate proc_macro;
diff --git a/rust/proc-macro2/rcvec.rs b/rust/proc-macro2/rcvec.rs
index 23edc77d597f..e224ebe277ef 100644
--- a/rust/proc-macro2/rcvec.rs
+++ b/rust/proc-macro2/rcvec.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use alloc::rc::Rc;
 use alloc::vec;
 use core::mem;
diff --git a/rust/proc-macro2/wrapper.rs b/rust/proc-macro2/wrapper.rs
index 2e3eb5b4d04e..6792e9834111 100644
--- a/rust/proc-macro2/wrapper.rs
+++ b/rust/proc-macro2/wrapper.rs
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
 use crate::detection::inside_proc_macro;
 use crate::fallback::{self, FromStr2 as _};
 #[cfg(span_locations)]
-- 
2.52.0