[PATCH] rust: kbuild: emit dep-info into $(depfile) directly

[PATCH] rust: kbuild: emit dep-info into $(depfile) directly

[Gary Guo]

After commit 295d8398c67e ("kbuild: specify output names separately for
each emission type from rustc"), the preferred pattern is to ask rustc to
emit depedency information into $(depfile) directly, and after commit
2185242faddd ("kbuild: remove sed commands after rustc rules"), the
post-processing to remove comments is no longer necessary as fixdep can
handle comments directly. Thus, emit dep-ifno into $(depfile) directly and
remove the mv and sed invocation.

This fixes the issue where a non-ignored .d file is emitted during
compilation and removed shortly afterwards.

Reported-by: Onur Özkan <work@onurozkan.dev>
Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/syn.20artifact.20being.20tracked.20by.20git/with/575467879
Fixes: 7dbe46c0b11d ("rust: kbuild: add proc macro library support")
Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/Makefile | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/rust/Makefile b/rust/Makefile
index 629b3bdd2b20..1500993d7ecc 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -526,11 +526,9 @@ quiet_cmd_rustc_procmacrolibrary = $(RUSTC_OR_CLIPPY_QUIET) PL $@
       cmd_rustc_procmacrolibrary = \
 	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
 		$(filter-out $(skip_flags),$(rust_common_flags) $(rustc_target_flags)) \
-		--emit=dep-info,link --crate-type rlib -O \
+		--emit=dep-info=$(depfile) --emit=link=$@ --crate-type rlib -O \
 		--out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \
-		--crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<; \
-	mv $(objtree)/$(obj)/$(patsubst lib%.rlib,%,$(notdir $@)).d $(depfile); \
-	sed -i '/^\#/d' $(depfile)
+		--crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<
 
 $(obj)/libproc_macro2.rlib: private skip_clippy = 1
 $(obj)/libproc_macro2.rlib: private rustc_target_flags = $(proc_macro2-flags)
-- 
2.51.2

Re: [PATCH] rust: kbuild: emit dep-info into $(depfile) directly

[Onur Özkan]

On Tue, 24 Feb 2026 15:29:56 +0800
Gary Guo <gary@garyguo.net> wrote:

> After commit 295d8398c67e ("kbuild: specify output names separately
> for each emission type from rustc"), the preferred pattern is to ask
> rustc to emit depedency information into $(depfile) directly, and
> after commit 2185242faddd ("kbuild: remove sed commands after rustc
> rules"), the post-processing to remove comments is no longer
> necessary as fixdep can handle comments directly. Thus, emit dep-ifno
> into $(depfile) directly and remove the mv and sed invocation.
> 
> This fixes the issue where a non-ignored .d file is emitted during
> compilation and removed shortly afterwards.
> 
> Reported-by: Onur Özkan <work@onurozkan.dev>
> Closes:
> https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/syn.20artifact.20being.20tracked.20by.20git/with/575467879
> Fixes: 7dbe46c0b11d ("rust: kbuild: add proc macro library support")
> Signed-off-by: Gary Guo <gary@garyguo.net> ---
>  rust/Makefile | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/rust/Makefile b/rust/Makefile
> index 629b3bdd2b20..1500993d7ecc 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -526,11 +526,9 @@ quiet_cmd_rustc_procmacrolibrary =
> $(RUSTC_OR_CLIPPY_QUIET) PL $@ cmd_rustc_procmacrolibrary = \
>  	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
>  		$(filter-out $(skip_flags),$(rust_common_flags)
> $(rustc_target_flags)) \
> -		--emit=dep-info,link --crate-type rlib -O \
> +		--emit=dep-info=$(depfile) --emit=link=$@
> --crate-type rlib -O \ --out-dir $(objtree)/$(obj)
> -L$(objtree)/$(obj) \
> -		--crate-name $(patsubst lib%.rlib,%,$(notdir $@))
> $<; \
> -	mv $(objtree)/$(obj)/$(patsubst lib%.rlib,%,$(notdir $@)).d
> $(depfile); \
> -	sed -i '/^\#/d' $(depfile)
> +		--crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<
>  
>  $(obj)/libproc_macro2.rlib: private skip_clippy = 1
>  $(obj)/libproc_macro2.rlib: private rustc_target_flags =
> $(proc_macro2-flags)

Tested-by: Onur Özkan <work@onurozkan.dev>

Re: [PATCH] rust: kbuild: emit dep-info into $(depfile) directly

[Miguel Ojeda]

On Tue, Feb 24, 2026 at 8:30 AM Gary Guo <gary@garyguo.net> wrote:
>
> After commit 295d8398c67e ("kbuild: specify output names separately for
> each emission type from rustc"), the preferred pattern is to ask rustc to
> emit depedency information into $(depfile) directly, and after commit
> 2185242faddd ("kbuild: remove sed commands after rustc rules"), the
> post-processing to remove comments is no longer necessary as fixdep can
> handle comments directly. Thus, emit dep-ifno into $(depfile) directly and
> remove the mv and sed invocation.
>
> This fixes the issue where a non-ignored .d file is emitted during
> compilation and removed shortly afterwards.
>
> Reported-by: Onur Özkan <work@onurozkan.dev>
> Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/syn.20artifact.20being.20tracked.20by.20git/with/575467879
> Fixes: 7dbe46c0b11d ("rust: kbuild: add proc macro library support")
> Signed-off-by: Gary Guo <gary@garyguo.net>

Applied to `rust-fixes` -- thanks everyone!

    [ Like Gary mentioned in Zulip, this likely happened due to rebasing
      the builds part of the old `syn` work I had. - Miguel ]

    [ Reworded for a couple of typos. - Miguel ]

Also Cc: stable@vger.kernel.org

Cheers,
Miguel