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Consider using Cargo's links feature to ensure use only once #137

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jamesmunns opened this issue Mar 16, 2019 · 5 comments · Fixed by #140
Closed

Consider using Cargo's links feature to ensure use only once #137

jamesmunns opened this issue Mar 16, 2019 · 5 comments · Fixed by #140

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@jamesmunns
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Currently cortex-m uses an unmangled variable to prevent multiple crates being linked in that redefine CORE_PERIPHERALS.

Cargo now has a feature called links that addresses this.
@little-arhat
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little-arhat commented Apr 23, 2019 •
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And how do I deal with this issue now?

I've have dependency on cortex-m: "=0.5.8", and dependency on cortex-m-log: "0.4.0" and everything worked fine for me, until suddenly some other crate brought cortex-m 0.6.0 and linker started to complain:

warning: Linking globals named 'CORE_PERIPHERALS': symbol multiply defined!

error: failed to load bc of "cortex_m.31bpwv5e-cgu.0":

looking at Cargo.lock I see that 0.6.0 is brough by cortex-m-semihosting (that cortex-m-log depends on):

[[package]]
name = "cortex-m-semihosting"
version = "0.3.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "cortex-m 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
]

[[package]]
name = "cortex-m-log"
version = "0.4.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "cortex-m 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "cortex-m-semihosting 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
]

cortex-m-log defines cortex-m dependency as cortex-m = ">= 0.5.8, < 0.7", and I have cortex-m = {version = "=0.5.8", features = ["inline-asm", "const-fn"]}, so I'm a bit surprised that 0.6.0 appeared in Cargo.lock.

(of course I can edit Cargo.lock and so on, but I'm surprised that I have to deal with this. I also wonder, what is the recommended way to deal with this, as I imagine some crates will be updated sooner than later to use 0.6.0).

@jamesmunns
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@little-arhat this issue is a little different than what you are reporting, but I have run into this too.

I have had problems where despite the >=5.8,<0.7 stuff, cargo decided to pick cortex-m 0.5.8 AND 0.6. I manually edited the Cargo.lock and it was happy, but this doesn't seem optimal.

I even selected cortex-m = "=0.5.8" in my top level crate, but cortex-m-semihosting (a sub-sub-dep) still decided to pull in 0.6.

I "fixed" this locally by editing:

[[package]]
name = "cortex-m-semihosting"
version = "0.3.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "cortex-m 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
]

to

[[package]]
name = "cortex-m-semihosting"
version = "0.3.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
 "cortex-m 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
]

Which seemed to work after a rebuild (and mentions of cortex-m 0.6.0 were automatically removed by cargo), but this is sub-optimal behavior. CC @rust-embedded/cortex-m

@little-arhat
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@jamesmunns thanks, that what I did as well, doesn't look pretty, indeed.

I guess links feature will not help in this case, as it will prevent linking, but will not alter solver behaviour (which is, I guess, responsible for the mess we're in %) ).

@jonas-schievink jonas-schievink mentioned this issue Apr 24, 2019
Merged
bors bot added a commit that referenced this issue Apr 24, 2019
@bors @jonas-schievink
Merge #140
f1df6a8 
140: Cargo.toml: Add `links = "cortex-m"` r=therealprof a=jonas-schievink

This prevents linking multiple versions of `cortex-m` together, which would be
unsound. Currently it uses a `#[no_mangle]` static for this, which isn't always
reliable.

Fixes #137

Co-authored-by: Jonas Schievink <[email protected]>
@little-arhat
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@jamesmunns I've created cargo issue for this, btw: rust-lang/cargo#6876

@Eh2406
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Eh2406 commented May 2, 2019 •
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BTW links dose efact the resolver rust-lang/cargo#4978

bors bot added a commit that referenced this issue Jun 6, 2019
@bors @jonas-schievink
Merge #140
ddebec2 
140: Cargo.toml: Add `links = "cortex-m"` r=therealprof a=jonas-schievink

This prevents linking multiple versions of `cortex-m` together, which would be
unsound. Currently it uses a `#[no_mangle]` static for this, which isn't always
reliable.

Fixes #137

Co-authored-by: Jonas Schievink <[email protected]>
@bors bors bot closed this as completed in #140 Jun 6, 2019
adamgreig pushed a commit that referenced this issue Jan 12, 2022
@birkenfeld
Mention interrupt attribute in main crate docs
2f2ad09 
Fixes #137
adamgreig pushed a commit that referenced this issue Jan 12, 2022
@bors @birkenfeld
Merge #146
2f890d8 
146: Mention interrupt attribute in main crate docs r=korken89 a=birkenfeld

Fixes #137

Co-authored-by: Georg Brandl <[email protected]>
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Cargo.toml: Add links = "cortex-m"
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@little-arhat @jamesmunns @Eh2406