Merge tag 'rust-fixes-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull rust fixes from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Work around a 'rustc' bug by setting the 'frame-pointer' LLVM
     module flag under 'CONFIG_FRAME_POINTER'.

     The upcoming Rust 1.98.0 is fixed.

   - Doctests: fix incorrect replacement pattern.

  'kernel' crate:

   - Mark 'Debug' impl as '#[inline]'"

* tag 'rust-fixes-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
  rust: Kbuild: set frame-pointer llvm module flag for CONFIG_FRAME_POINTER
  rust: doctest: fix incorrect pattern in replacement
  rust: bitfield: mark `Debug` impl as `#[inline]`

3 files changed, 14 insertions, 6 deletions

diff --git a/Makefile b/Makefile
index e3c24951d41b..fae409cd524d 100644
--- a/Makefile
+++ b/Makefile
@@ -961,6 +961,9 @@ KBUILD_CFLAGS += $(stackp-flags-y)
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y
+# Work around rustc bug on compilers without
+# https://github.com/rust-lang/rust/pull/156980.
+KBUILD_RUSTFLAGS += $(if $(call rustc-min-version,109800),,-Zllvm_module_flag=frame-pointer:u32:2:max)
 else
 # Some targets (ARM with Thumb2, for example), can't be built with frame
 # pointers.  For those, we don't have FUNCTION_TRACER automatically
diff --git a/rust/kernel/bitfield.rs b/rust/kernel/bitfield.rs
index 554a5a2ff0ab..35ede53f2b8e 100644
--- a/rust/kernel/bitfield.rs
+++ b/rust/kernel/bitfield.rs
@@ -535,6 +535,7 @@ macro_rules! bitfield {
     // `Debug` implementation.
     (@debug $name:ident { $($field:ident;)* }) => {
         impl ::kernel::fmt::Debug for $name {
+            #[inline]
             fn fmt(&self, f: &mut ::kernel::fmt::Formatter<'_>) -> ::kernel::fmt::Result {
                 f.debug_struct(stringify!($name))
                     .field("<raw>", &::kernel::prelude::fmt!("{:#x}", self.inner))
diff --git a/scripts/rustdoc_test_builder.rs b/scripts/rustdoc_test_builder.rs
index f7540bcf595a..df864437cef7 100644
--- a/scripts/rustdoc_test_builder.rs
+++ b/scripts/rustdoc_test_builder.rs
@@ -28,7 +28,7 @@ fn main() {
     //
     // ```
     // fn main() { #[allow(non_snake_case)] fn _doctest_main_rust_kernel_file_rs_28_0() {
-    // fn main() { #[allow(non_snake_case)] fn _doctest_main_rust_kernel_file_rs_37_0() -> Result<(), impl ::core::fmt::Debug> {
+    // fn main() { #[allow(non_snake_case)] fn _doctest_main_rust_kernel_file_rs_37_0() -> Result<(), impl core::fmt::Debug> {
     // ```
     //
     // It should be unlikely that doctest code matches such lines (when code is formatted properly).
@@ -47,12 +47,16 @@ fn main() {
         })
         .expect("No test function found in `rustdoc`'s output.");
 
-    // Qualify `Result` to avoid the collision with our own `Result` coming from the prelude.
+    // Replicate `rustdoc` 1.87+ behaviour [1] by fully qualifying `Result` to avoid the collision
+    // with our own `Result` coming from the prelude.
+    //
+    // [1]: https://github.com/rust-lang/rust/pull/137807
+    //
+    // TODO: Remove this when MSRV is bumped above 1.87.
     let body = body.replace(
-        &format!("{rustdoc_function_name}() -> Result<(), impl ::core::fmt::Debug> {{"),
-        &format!(
-            "{rustdoc_function_name}() -> ::core::result::Result<(), impl ::core::fmt::Debug> {{"
-        ),
+        &format!("{rustdoc_function_name}() -> Result<(), impl core::fmt::Debug> {{"),
+        // This intentionally does not use absolute paths to match `rustdoc` 1.87 behaviour.
+        &format!("{rustdoc_function_name}() -> core::result::Result<(), impl core::fmt::Debug> {{"),
     );
 
     // For tests that get generated with `Result`, like above, `rustdoc` generates an `unwrap()` on