With the minimum version bump in place, `rustdoc` now always recognizes
the `--remap-path-prefix` flag.

In addition, the Internal Compiler Error that the comment mentions [1]
was fixed in Rust 1.87.0 [2], so we still need to skip the flag for
the normal `rustdoc` case, but not for `--test` since the ICE does not
reproduce there -- please see commit 2c8725c1dca3 ("rust: kbuild: skip
`--remap-path-prefix` for `rustdoc`").

Thus update the comment and remove the skipping of the flag for the
`--test` case.

Note that commit dda135077ecc ("rust: build: remap path to avoid
absolute path") re-landed the `--remap-path-prefix` flag (together with
`--remap-path-scope`), so we keep the workaround, i.e. an alternative
could have been to simply delete the skip entirely, but since we still
have it and it will be needed when this gets merged, let's keep it.

Link: https://github.com/rust-lang/rust/issues/138520 [1]
Link: https://github.com/rust-lang/rust/pull/138556 [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/Makefile | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/rust/Makefile b/rust/Makefile
index 193cf06eea64..708530ee3613 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -142,10 +142,9 @@ rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-a
 # Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
 doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
 
-# `rustc` recognizes `--remap-path-prefix` since 1.26.0, but `rustdoc` only
-# since Rust 1.81.0. Moreover, `rustdoc` ICEs on out-of-tree builds since Rust
-# 1.82.0 (https://github.com/rust-lang/rust/issues/138520). Thus workaround both
-# issues skipping the flag. The former also applies to `RUSTDOC TK`.
+# `rustdoc` ICEs on out-of-tree builds in Rust < 1.87.0
+# (https://github.com/rust-lang/rust/issues/138520). Thus workaround the
+# issue skipping the flag.
 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
 	OBJTREE=$(abspath $(objtree)) \
@@ -333,7 +332,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
 	rm -rf $(objtree)/$(obj)/test/doctests/kernel; \
 	mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \
 	OBJTREE=$(abspath $(objtree)) \
-	$(RUSTDOC) --test $(filter-out --remap-path-prefix=%,$(rust_flags)) \
+	$(RUSTDOC) --test $(rust_flags) \
 		-L$(objtree)/$(obj) --extern ffi --extern pin_init \
 		--extern kernel --extern build_error --extern macros \
 		--extern bindings --extern uapi \
-- 
2.53.0