Test linking and running no_std binaries
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| // Need to link libSystem on Apple platforms, otherwise the linker fails with: | ||
| // > ld: dynamic executables or dylibs must link with libSystem.dylib | ||
| // | ||
| // With the new linker introduced in Xcode 15, the error is instead: | ||
| // > Undefined symbols: "dyld_stub_binder", referenced from: <initial-undefines> | ||
| // | ||
| // This _can_ be worked around by raising the deployment target with | ||
| // MACOSX_DEPLOYMENT_TARGET=13.0, though it's a bit hard to test that while | ||
| // still allowing the test suite to support running with older Xcode versions. | ||
| #[cfg_attr(target_vendor = "apple", link(name = "System"))] | ||
| extern "C" {} |
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We could just always link libSystem internally in rustc, but I'm not sure that's a good idea, since as noted, it is possible to create a fully no_std binary that doesn't link libSystem, it just requires the user to do some work.
Maybe better would be to document the limitation somewhere (where?)? Note that libc does the linking internally too (linking to libc.dylib also links to libSystem.dylib), so any code that does #![no_std] but uses libc works without this.
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For completeness, there is https://github.com/rust-lang/rust/blob/master/tests/run-make/thumb-none-qemu/example/src/main.rs so it's not completely untested, but coverage on more platforms is good of course. |
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| //@ run-pass | ||
| //@ compile-flags: -Cpanic=abort | ||
| //@ ignore-wasm different `main` convention |
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Unsure if we need to add more to the ignores here? Is something like ignore-embedded a thing, and would it make sense?
Ah nice. Do you think I should try to merge this test with that? |
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I don't think so, that test is very specifically for checking that the embedded ecosystem continues to work. It uses qemu to run on a simulated microcontroller. So instead additionally having this test for many more platforms in the ui tests seems independently useful. |
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| // # Linux | ||
| // | ||
| // Linking `libc` is required by crt1.o, otherwise the linker fails with: |
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it would be fun to have a _start lib-less linux binary as well
I looked around, but it seems that we do not have a test that tests a
#![no_std]+#![no_main]binary. So now I've added one. Motivated by discussion in this Zulip thread.r? @tgross35
I haven't tested on Windows, so:
try-run: dist-x86_64-msvc
And only tested lightly on Linux, so:
try-run: dist-x86_64-linux