Add option to allow #[link] directives to be ignored #70093
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A-linkage
Area: linking into static, shared libraries and binaries
C-feature-request
Category: A feature request, i.e: not implemented / a PR.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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jsgf
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Mar 18, 2020
This implements a flag `-Zlink-native-libraries=yes/no`. If set to true/yes, or unspecified, then native libraries referenced via `#[link]` attributes will be put on the linker line (ie, unchanged behaviour). If `-Zlink-native-libraries=no` is specified then rustc will not add the native libraries to the link line. The assumption is that the outer build system driving the build already knows about the native libraries and will specify them to the linker directly (for example via `-Clink-arg=`). Addresses issue rust-lang#70093
jonas-schievink
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Centril
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Mar 19, 2020
Implement -Zlink-native-libraries This implements a flag `-Zlink-native-libraries=yes/no`. If set to true/yes, or unspecified, then native libraries referenced via `#[link]` attributes will be put on the linker line (ie, unchanged behaviour). If `-Zlink-native-libraries=no` is specified then rustc will not add the native libraries to the link line. The assumption is that the outer build system driving the build already knows about the native libraries and will specify them to the linker directly (for example via `-Clink-arg=`). Addresses issue rust-lang#70093
jsgf
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Mar 27, 2020
This implements a flag `-Zlink-native-libraries=yes/no`. If set to true/yes, or unspecified, then native libraries referenced via `#[link]` attributes will be put on the linker line (ie, unchanged behaviour). If `-Zlink-native-libraries=no` is specified then rustc will not add the native libraries to the link line. The assumption is that the outer build system driving the build already knows about the native libraries and will specify them to the linker directly (for example via `-Clink-arg=`). Addresses issue rust-lang#70093
bors
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Mar 28, 2020
Implement -Zlink-native-libraries This implements a flag `-Zlink-native-libraries=yes/no`. If set to true/yes, or unspecified, then native libraries referenced via `#[link]` attributes will be put on the linker line (ie, unchanged behaviour). If `-Zlink-native-libraries=no` is specified then rustc will not add the native libraries to the link line. The assumption is that the outer build system driving the build already knows about the native libraries and will specify them to the linker directly (for example via `-Clink-arg=`). Addresses issue rust-lang#70093
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Resolved by #70095 |
jsgf
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Feb 22, 2023
`-Zlink-directives=no` will ignored `#[link]` directives while compiling a crate, so nothing is emitted into the crate's metadata. The assumption is that the build system already knows about the crate's native dependencies and can provide them at link time without these directives. This is another way to address issue # rust-lang#70093, which is currently addressed by `-Zlink-native-libraries` (implemented in rust-lang#70095). The latter is implemented at link time, which has the effect of ignoring `#[link]` in *every* crate. This makes it a very large hammer as it requires all native dependencies to be known to the build system to be at all usable, including those in sysroot libraries. I think this means its effectively unused, and definitely under-used. Being able to control this on a crate-by-crate basis should make it much easier to apply when needed. I'm not sure if we need both mechanisms, but we can decide that later.
compiler-errors
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Feb 25, 2023
Implement -Zlink-directives=yes/no `-Zlink-directives=no` will ignored `#[link]` directives while compiling a crate, so nothing is emitted into the crate's metadata. The assumption is that the build system already knows about the crate's native dependencies and can provide them at link time without these directives. This is another way to address issue # rust-lang#70093, which is currently addressed by `-Zlink-native-libraries` (implemented in rust-lang#70095). The latter is implemented at link time, which has the effect of ignoring `#[link]` in *every* crate. This makes it a very large hammer as it requires all native dependencies to be known to the build system to be at all usable, including those in sysroot libraries. I think this means its effectively unused, and definitely under-used. Being able to control this on a crate-by-crate basis should make it much easier to apply when needed. I'm not sure if we need both mechanisms, but we can decide that later. cc `@pcwalton` `@cramertj`
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In a non-Cargo build system (eg Buck) dependencies on native libraries are already defined in the build system. As such the build system will automatically put those libraries on the link line, which means that rustc should not do so. It would be nice to have an option to allow this (proposal:
-Zlink-native-libraries=yes/no, to be stabilized as-Clink-native-libraries=yes/no).Idea mentioned in #64191
cc @cramertj
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