Frivolous native-static-libs warning when building a cdylib with Cargo-C on macOS

[amyspark]

Code

Try building GStreamer's gst-plugins-rs against the 1.26 SDK. (Linked the branch in which I had this issue happen.)

Do not use cargo build, use cargo-c's cargo cbuild command in order to generate the dylibs and the pkg-config modules:

cargo +nightly cbuild --release --library-type cdylib

Current output

   Compiling cfg-if v1.0.0
   (...continues...)
   Compiling gst-plugin-webrtc-signalling-protocol v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc/protocol)
warning: cannot output linkage information without staticlib crate-type

note: consider `--crate-type staticlib` to print linkage information

warning: `gst-plugin-webrtc-signalling-protocol` (lib) generated 1 warning
   Compiling byteorder_slice v3.0.0
   Compiling cookie-factory v0.3.3
   Compiling web-transport-proto v0.2.6
   Compiling yasna v0.5.2
   Compiling lru v0.12.5
   Compiling headers-core v0.3.0
   Compiling nanorand v0.7.0
   Compiling sprintf v0.4.2
   Compiling itertools v0.12.1
   Compiling bstr v1.12.0
   Compiling toml_datetime v0.6.9
   Compiling same-file v1.0.6
   Compiling weezl v0.1.8
   Compiling smawk v0.3.2
   Compiling scoped-tls v1.0.1
   Compiling new_debug_unreachable v1.0.6
   Compiling cdg v0.1.0
   Compiling unicode-width v0.2.0
   Compiling unicode-linebreak v0.1.5
   Compiling bitstream-io v2.6.0
   Compiling color_quant v1.1.0
   Compiling winnow v0.7.10
   Compiling fallible-iterator v0.3.0
   Compiling jiff v0.2.14
   Compiling gif v0.13.1
   Compiling sdp-types v0.1.8
   Compiling textwrap v0.16.2
   Compiling cdg_renderer v0.8.0
   Compiling warp v0.3.7
   Compiling walkdir v2.5.0
   Compiling toml_edit v0.22.26
   Compiling async-stream v0.3.6
   Compiling gst-plugin-rav1e v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/rav1e)
   Compiling gst-plugin-textwrap v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/wrap)
   Compiling gst-plugin-uriplaylistbin v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/uriplaylistbin)
   Compiling gst-plugin-raptorq v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/raptorq)
   Compiling gst-plugin-webrtchttp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtchttp)
   Compiling gst-plugin-inter v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/inter)
   Compiling gst-plugin-ndi v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/ndi)
   Compiling env_logger v0.11.8
   Compiling gst-plugin-rtsp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/rtsp)
   Compiling gst-plugin-regex v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/regex)
   Compiling gst-plugin-skia v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/skia)
   Compiling gst-plugin-hlssink3 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/hlssink3)
   Compiling gst-plugin-aws v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/aws)
   Compiling gst-plugin-gopbuffer v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/gopbuffer)
   Compiling gst-plugin-relationmeta v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/relationmeta)
   Compiling gst-plugin-mp4 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/mux/mp4)
   Compiling gst-plugin-hsv v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/hsv)
   Compiling gst-plugin-json v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/json)
   Compiling gst-plugin-reqwest v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/reqwest)
   Compiling gst-plugin-claxon v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/claxon)
   Compiling gst-plugin-textahead v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/ahead)
   Compiling gst-plugin-quinn v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/quinn)
   Compiling gst-plugin-streamgrouper v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/streamgrouper)
   Compiling gst-plugin-lewton v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/lewton)
   Compiling gst-plugin-webrtc v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc)
   Compiling gst-plugin-gif v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/gif)
   Compiling gst-plugin-originalbuffer v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/originalbuffer)
   Compiling gst-plugin-mpegtslive v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/mpegtslive)
   Compiling gst-plugin-ffv1 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/ffv1)
   Compiling gst-plugin-cdg v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/cdg)
   Compiling gst-plugin-fallbackswitch v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/fallbackswitch)
   Compiling gst-plugin-livesync v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/livesync)
   Compiling gst-plugin-onvif v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/onvif)
   Compiling gst-plugin-png v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/png)
   Compiling gst-plugin-tracers v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/tracers)
   Compiling rustls-platform-verifier v0.5.3
   Compiling gst-plugin-audiofx v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/audiofx)
   Compiling gst-plugin-fmp4 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/mux/fmp4)
   Compiling quinn-proto v0.11.12
   Compiling gst-plugin-togglerecord v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/togglerecord)
   Compiling gst-plugin-rtp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/rtp)
   Compiling rcgen v0.13.2
   Compiling flume v0.11.1
   Compiling aws-config v1.5.18
   Compiling rtsp-types v0.1.3
   Compiling gst-plugin-threadshare v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/threadshare)
   Compiling headers v0.4.0
   Compiling aws-sdk-s3 v1.76.0
   Compiling pcap-file v2.0.0
   Compiling web-transport-quinn v0.5.1
   Compiling gst-plugin-webrtc-signalling v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc/signalling)
   Compiling png v0.17.16
   Compiling pangocairo v0.21.0 (https://github.com/gtk-rs/gtk-rs-core?branch=main#8b1c516f)
   Compiling polling v3.7.4
   Compiling ctrlc v3.4.7
   Compiling async-channel v2.3.1
   Compiling gstreamer-analytics v0.24.0 (https://gitlab.freedesktop.org/gstreamer/gstreamer-rs?branch=main#c3d3ce5f)
   Compiling serde_with v3.12.0
   Compiling hrtf v0.8.1
   Compiling skia-safe v0.84.0
warning: `gst-plugin-webrtc-signalling` (lib) generated 1 warning (1 duplicate)
   (...continues...)

Desired output

$ cargo +nightly cbuild --release --library-type cdylib 
   Compiling cfg-if v1.0.0
   (...continues...)
   Compiling gst-plugin-webrtc-signalling-protocol v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc/protocol)
   Compiling byteorder_slice v3.0.0
   Compiling cookie-factory v0.3.3
   Compiling web-transport-proto v0.2.6
   Compiling yasna v0.5.2
   Compiling lru v0.12.5
   Compiling headers-core v0.3.0
   Compiling nanorand v0.7.0
   Compiling sprintf v0.4.2
   Compiling itertools v0.12.1
   Compiling bstr v1.12.0
   Compiling toml_datetime v0.6.9
   Compiling same-file v1.0.6
   Compiling weezl v0.1.8
   Compiling smawk v0.3.2
   Compiling scoped-tls v1.0.1
   Compiling new_debug_unreachable v1.0.6
   Compiling cdg v0.1.0
   Compiling unicode-width v0.2.0
   Compiling unicode-linebreak v0.1.5
   Compiling bitstream-io v2.6.0
   Compiling color_quant v1.1.0
   Compiling winnow v0.7.10
   Compiling fallible-iterator v0.3.0
   Compiling jiff v0.2.14
   Compiling gif v0.13.1
   Compiling sdp-types v0.1.8
   Compiling textwrap v0.16.2
   Compiling cdg_renderer v0.8.0
   Compiling warp v0.3.7
   Compiling walkdir v2.5.0
   Compiling toml_edit v0.22.26
   Compiling async-stream v0.3.6
   Compiling gst-plugin-rav1e v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/rav1e)
   Compiling gst-plugin-textwrap v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/wrap)
   Compiling gst-plugin-uriplaylistbin v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/uriplaylistbin)
   Compiling gst-plugin-raptorq v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/raptorq)
   Compiling gst-plugin-webrtchttp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtchttp)
   Compiling gst-plugin-inter v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/inter)
   Compiling gst-plugin-ndi v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/ndi)
   Compiling env_logger v0.11.8
   Compiling gst-plugin-rtsp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/rtsp)
   Compiling gst-plugin-regex v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/regex)
   Compiling gst-plugin-skia v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/skia)
   Compiling gst-plugin-hlssink3 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/hlssink3)
   Compiling gst-plugin-aws v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/aws)
   Compiling gst-plugin-gopbuffer v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/gopbuffer)
   Compiling gst-plugin-relationmeta v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/relationmeta)
   Compiling gst-plugin-mp4 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/mux/mp4)
   Compiling gst-plugin-hsv v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/hsv)
   Compiling gst-plugin-json v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/json)
   Compiling gst-plugin-reqwest v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/reqwest)
   Compiling gst-plugin-claxon v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/claxon)
   Compiling gst-plugin-textahead v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/text/ahead)
   Compiling gst-plugin-quinn v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/quinn)
   Compiling gst-plugin-streamgrouper v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/streamgrouper)
   Compiling gst-plugin-lewton v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/lewton)
   Compiling gst-plugin-webrtc v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc)
   Compiling gst-plugin-gif v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/gif)
   Compiling gst-plugin-originalbuffer v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/originalbuffer)
   Compiling gst-plugin-mpegtslive v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/mpegtslive)
   Compiling gst-plugin-ffv1 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/ffv1)
   Compiling gst-plugin-cdg v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/cdg)
   Compiling gst-plugin-fallbackswitch v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/fallbackswitch)
   Compiling gst-plugin-livesync v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/livesync)
   Compiling gst-plugin-onvif v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/onvif)
   Compiling gst-plugin-png v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/video/png)
   Compiling gst-plugin-tracers v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/tracers)
   Compiling rustls-platform-verifier v0.5.3
   Compiling gst-plugin-audiofx v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/audio/audiofx)
   Compiling gst-plugin-fmp4 v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/mux/fmp4)
   Compiling quinn-proto v0.11.12
   Compiling gst-plugin-togglerecord v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/utils/togglerecord)
   Compiling gst-plugin-rtp v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/rtp)
   Compiling rcgen v0.13.2
   Compiling flume v0.11.1
   Compiling aws-config v1.5.18
   Compiling rtsp-types v0.1.3
   Compiling gst-plugin-threadshare v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/generic/threadshare)
   Compiling headers v0.4.0
   Compiling aws-sdk-s3 v1.76.0
   Compiling pcap-file v2.0.0
   Compiling web-transport-quinn v0.5.1
   Compiling gst-plugin-webrtc-signalling v0.14.0-alpha.1 (/Volumes/Centricular/gstreamer/subprojects/gst-plugins-rs/net/webrtc/signalling)
   Compiling png v0.17.16
   Compiling pangocairo v0.21.0 (https://github.com/gtk-rs/gtk-rs-core?branch=main#8b1c516f)
   Compiling polling v3.7.4
   Compiling ctrlc v3.4.7
   Compiling async-channel v2.3.1
   Compiling gstreamer-analytics v0.24.0 (https://gitlab.freedesktop.org/gstreamer/gstreamer-rs?branch=main#c3d3ce5f)
   Compiling serde_with v3.12.0
   Compiling hrtf v0.8.1
   Compiling skia-safe v0.84.0
   (...continues...)

Rationale and extra context

#138139 introduced a new warning for when native-static-libs is used against a non-staticlib crate. This rustc flag is used by Cargo-C to determine the link line that should go inside the pkg-config module for the corresponding library.

I do not know why the warning was introduced, but in non-staticlib, non-cdylib crates like the one highlighted earlier, it seems to be redundant.

Other cases

Rust Version

rustc 1.89.0-nightly (e703dff8f 2025-06-11)
binary: rustc
commit-hash: e703dff8fe220b78195c53478e83fb2f68d8499c
commit-date: 2025-06-11
host: aarch64-apple-darwin
release: 1.89.0-nightly
LLVM version: 20.1.5

Anything else?

Downstream bug report: lu-zero/cargo-c#469

[workingjubilee]

cc @xizheyin @ChrisDenton

[ChrisDenton]

Personally I'd be in favour of just reverting it.

[workingjubilee]

The warning does not seem to be spurious, in that it is technically correct.

It just seems to be of dubious value in its current overeager state.

[workingjubilee]

Specifically, I think the warning focuses on --print native-static-libs instead of considering --emit metadata, which is what makes it so we won't emit the relevant binary, to be the "true offender" here.

[xizheyin]

The warning about --print native-static-libs may be problematic because it doesn't consider the complexity of modern build systems. When using tools like Cargo-C to build a cdylib, this warning is potentially confusing, since the user's intent is clearly to build a dynamic library.

We could target a narrower set of use cases or shifts focus to --emit instead of --print native-static-libs. This would make the compiler's feedback more meaningful in real-world build scenarios.