rustc: Add a new crate type, cdylib #33553

alexcrichton · 2016-05-11T01:24:02Z

This commit is an implementation of RFC 1510 which adds a new crate type,
cdylib, to the compiler. This new crate type differs from the existing dylib
crate type in a few key ways:

No metadata is present in the final artifact
Symbol visibility rules are the same as executables, that is only reachable
extern functions are visible symbols
LTO is allowed
All libraries are always linked statically

This commit is relatively simple by just plubming the compiler with another
crate type which takes different branches here and there. The only major change
is an implementation of the Linker::export_symbols function on Unix which now
actually does something. This helps restrict the public symbols from a cdylib on
Unix.

With this PR a "hello world" cdylib is 7.2K while the same dylib is 2.4MB,
which is some nice size savings!

Closes #33132

rust-highfive · 2016-05-11T01:24:06Z

r? @jroesch

(rust_highfive has picked a reviewer for you, use r? to override)

alexcrichton · 2016-05-11T01:24:08Z

r? @brson

brson · 2016-05-13T01:20:07Z

@bors r+

bors · 2016-05-13T01:20:08Z

📌 Commit a3f5d08 has been approved by brson

eddyb · 2016-05-13T05:49:04Z

src/librustc_trans/back/linker.rs

+        let res = (|| -> io::Result<()> {
+            let mut f = BufWriter::new(File::create(&path)?);
+            for sym in exported_symbols(sess, trans, crate_type) {
+                writeln!(f, "  {}", sym)?;


This doesn't seem to be enough for iOS, see failure.

eddyb · 2016-05-13T05:49:33Z

@bors r- Likely responsible for this failure.

alexcrichton · 2016-05-13T06:08:39Z

Indeed! looks quite suspicious

alexcrichton · 2016-05-13T06:10:13Z

@bors: r=brson bfe7a80

Manishearth · 2016-05-14T09:56:47Z

Travis fails

bors · 2016-05-14T13:49:11Z

⌛ Testing commit bfe7a80 with merge 2d45326...

bors · 2016-05-14T14:15:44Z

💔 Test failed - auto-mac-64-opt-rustbuild

eddyb · 2016-05-14T14:37:22Z

I'm working on rebasing this over #33602 because otherwise I'd need windows to investigate my metadata problem.
Could be delayed for a few days by my flight, so if you don't hear anything from me, feel free to merge this.

alexcrichton · 2016-05-17T16:11:30Z

@bors: r=brson 557aae0

@eddyb I've applied your patch to retain the metadata symbol for dylibs, let's see how far it gets...

bors · 2016-05-17T18:41:56Z

⌛ Testing commit 557aae0 with merge 3ad8865...

bors · 2016-05-17T19:42:48Z

💔 Test failed - auto-linux-64-opt-rustbuild

rustc: Add a new crate type, cdylib This commit is an implementation of [RFC 1510] which adds a new crate type, `cdylib`, to the compiler. This new crate type differs from the existing `dylib` crate type in a few key ways: * No metadata is present in the final artifact * Symbol visibility rules are the same as executables, that is only reachable `extern` functions are visible symbols * LTO is allowed * All libraries are always linked statically This commit is relatively simple by just plubming the compiler with another crate type which takes different branches here and there. The only major change is an implementation of the `Linker::export_symbols` function on Unix which now actually does something. This helps restrict the public symbols from a cdylib on Unix. With this PR a "hello world" `cdylib` is 7.2K while the same `dylib` is 2.4MB, which is some nice size savings! [RFC 1510]: rust-lang/rfcs#1510 Closes #33132

bors · 2016-05-19T04:19:06Z

💔 Test failed - auto-linux-musl-64-opt

alexcrichton · 2016-05-19T16:38:44Z

@bors: r=brson 0192796

bors · 2016-05-19T20:50:26Z

⌛ Testing commit 0192796 with merge 89347bf...

bors · 2016-05-19T22:17:35Z

💔 Test failed - auto-mac-64-nopt-t

This commit is an implementation of [RFC 1510] which adds a new crate type, `cdylib`, to the compiler. This new crate type differs from the existing `dylib` crate type in a few key ways: * No metadata is present in the final artifact * Symbol visibility rules are the same as executables, that is only reachable `extern` functions are visible symbols * LTO is allowed * All libraries are always linked statically This commit is relatively simple by just plubming the compiler with another crate type which takes different branches here and there. The only major change is an implementation of the `Linker::export_symbols` function on Unix which now actually does something. This helps restrict the public symbols from a cdylib on Unix. With this PR a "hello world" `cdylib` is 7.2K while the same `dylib` is 2.4MB, which is some nice size savings! [RFC 1510]: rust-lang/rfcs#1510 Closes rust-lang#33132

alexcrichton · 2016-05-19T22:32:21Z

@bors: r=brson 0d2c26c

bors · 2016-05-20T07:34:51Z

⌛ Testing commit 0d2c26c with merge d27bdaf...

rustc: Add a new crate type, cdylib This commit is an implementation of [RFC 1510] which adds a new crate type, `cdylib`, to the compiler. This new crate type differs from the existing `dylib` crate type in a few key ways: * No metadata is present in the final artifact * Symbol visibility rules are the same as executables, that is only reachable `extern` functions are visible symbols * LTO is allowed * All libraries are always linked statically This commit is relatively simple by just plubming the compiler with another crate type which takes different branches here and there. The only major change is an implementation of the `Linker::export_symbols` function on Unix which now actually does something. This helps restrict the public symbols from a cdylib on Unix. With this PR a "hello world" `cdylib` is 7.2K while the same `dylib` is 2.4MB, which is some nice size savings! [RFC 1510]: rust-lang/rfcs#1510 Closes #33132

bors · 2016-05-20T11:34:32Z

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-32cross-opt, auto-linux-64-cargotest, auto-linux-64-cross-armhf, auto-linux-64-cross-armsf, auto-linux-64-cross-freebsd, auto-linux-64-cross-netbsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-mir, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-cross-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-mir, auto-win-msvc-64-opt-rustbuild

bluss · 2016-05-21T19:57:42Z

This is kind of immediately a new feature on the stable release where this is included, isn't it? If I'm wrong, then the relnote tag can be removed again.

torkleyy · 2017-04-09T13:36:17Z

@alexcrichton How can I compile a crate as cdylib without modifying Cargo.toml? I thought it would be cargo rustc -- --crate-type cdylib, but the crate-type option is just ignored.

alexcrichton · 2017-04-10T14:05:41Z

@torkleyy unfortunately that's not possible right now (short of generating a new Cargo.toml. Would you like to open a new issue at rust-lang/cargo?

torkleyy · 2017-04-10T14:12:23Z

@alexcrichton Thanks for your reply!

Would you like to open a new issue at rust-lang/cargo?

Sure, I'll do that.

rust-highfive assigned jroesch May 11, 2016

rust-highfive assigned brson and unassigned jroesch May 11, 2016

brson closed this May 13, 2016

brson reopened this May 13, 2016

eddyb mentioned this pull request May 13, 2016

Rollup of 29 pull requests #33610

Closed

eddyb reviewed May 13, 2016
View reviewed changes

alexcrichton force-pushed the cdylibs branch from a3f5d08 to bfe7a80 Compare May 13, 2016 06:10

alexcrichton force-pushed the cdylibs branch from bfe7a80 to 557aae0 Compare May 17, 2016 16:10

alexcrichton force-pushed the cdylibs branch from 557aae0 to e3517db Compare May 17, 2016 21:58

alexcrichton force-pushed the cdylibs branch from 698ba68 to 0192796 Compare May 19, 2016 16:38

alexcrichton and others added 2 commits May 19, 2016 15:32

Mark the metadata symbol as reachable to fix OSX not finding dylibs.

0d2c26c

alexcrichton force-pushed the cdylibs branch from 0192796 to 0d2c26c Compare May 19, 2016 22:32

bors merged commit 0d2c26c into rust-lang:master May 20, 2016

bors mentioned this pull request May 20, 2016

rustc_trans: implement lld compatibility #33327

Closed

bluss added the relnotes Marks issues that should be documented in the release notes of the next release. label May 21, 2016

briansmith mentioned this pull request May 23, 2016

Switch to cdylib crate type briansmith/ring-ffi#4

Open

tomaka mentioned this pull request May 24, 2016

Consider switching to cdylibs rust-mobile/android-rs-glue#100

Open

pravic mentioned this pull request May 24, 2016

Consider switching to cdylib pravic/winapi-kmd-rs#8

Closed

sdroege mentioned this pull request May 24, 2016

Use cdylib crate type once available in stable Rust sdroege/gst-plugin-rs#5

Closed

alexcrichton deleted the cdylibs branch May 25, 2016 00:21

SSheldon mentioned this pull request Jun 25, 2016

Linker error for cdylib with panic=abort (Undefined symbol "_rust_eh_personality_catch") #34472

Open

baby-bell mentioned this pull request Sep 1, 2016

Change crate type to cdylib shepmaster/rust-ffi-omnibus#40

Closed

rcatolino mentioned this pull request Jun 15, 2018

Cannot get example to run rcatolino/pam_sm_rust#2

Closed

Walther mentioned this pull request Oct 10, 2018

cargo run --example false positive "is a library and cannot be executed" rust-lang/cargo#6159

Closed

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rustc: Add a new crate type, cdylib #33553

rustc: Add a new crate type, cdylib #33553

alexcrichton commented May 11, 2016

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torkleyy commented Apr 10, 2017

rustc: Add a new crate type, cdylib #33553

rustc: Add a new crate type, cdylib #33553

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