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rustc: Link entire archives of native libraries
As discovered in #15460, a particular #[link(kind = "static", ...)] line is not
actually guaranteed to link the library at all. The reason for this is that if
the external library doesn't have any referenced symbols in the object generated
by rustc, the entire library is dropped by the linker.

For dynamic native libraries, this is solved by passing -lfoo for all downstream
compilations unconditionally. For static libraries in rlibs this is solved
because the entire archive is bundled in the rlib. The only situation in which
this was a problem was when a static native library was linked to a rust dynamic
library.

This commit brings the behavior of dylibs in line with rlibs by passing the
--whole-archive flag to the linker when linking native libraries. On OSX, this
uses the -force_load flag. This flag ensures that the entire archive is
considered candidate for being linked into the final dynamic library.

This is a breaking change because if any static library is included twice in the
same compilation unit then the linker will start emitting errors about duplicate
definitions now. The fix for this would involve only statically linking to a
library once.

Closes #15460
[breaking-change]
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alexcrichton committed Aug 4, 2014
1 parent 31590bd commit 1ae1461
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Showing 15 changed files with 168 additions and 44 deletions.
3 changes: 3 additions & 0 deletions src/liballoc/heap.rs
Expand Up @@ -136,6 +136,9 @@ mod imp {
use libc::{c_char, c_int, c_void, size_t};

#[link(name = "jemalloc", kind = "static")]
#[cfg(not(test))]
extern {}

extern {
fn je_mallocx(size: size_t, flags: c_int) -> *mut c_void;
fn je_rallocx(ptr: *mut c_void, size: size_t,
Expand Down
65 changes: 49 additions & 16 deletions src/librustc/back/link.rs
Expand Up @@ -9,6 +9,7 @@
// except according to those terms.

use super::archive::{Archive, ArchiveBuilder, ArchiveConfig, METADATA_FILENAME};
use super::archive;
use super::rpath;
use super::rpath::RPathConfig;
use super::svh::Svh;
Expand Down Expand Up @@ -1597,29 +1598,61 @@ fn add_local_native_libraries(cmd: &mut Command, sess: &Session) {
// For those that support this, we ensure we pass the option if the library
// was flagged "static" (most defaults are dynamic) to ensure that if
// libfoo.a and libfoo.so both exist that the right one is chosen.
let takes_hints = sess.targ_cfg.os != abi::OsMacos && sess.targ_cfg.os != abi::OsiOS;
let takes_hints = sess.targ_cfg.os != abi::OsMacos &&
sess.targ_cfg.os != abi::OsiOS;

let libs = sess.cstore.get_used_libraries();
let libs = libs.borrow();

let mut staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
if kind == cstore::NativeStatic {Some(l)} else {None}
});
let mut others = libs.iter().filter(|&&(_, kind)| {
kind != cstore::NativeStatic
});

// Platforms that take hints generally also support the --whole-archive
// flag. We need to pass this flag when linking static native libraries to
// ensure the entire library is included.
//
// For more details see #15460, but the gist is that the linker will strip
// away any unused objects in the archive if we don't otherwise explicitly
// reference them. This can occur for libraries which are just providing
// bindings, libraries with generic functions, etc.
if takes_hints {
cmd.arg("-Wl,--whole-archive").arg("-Wl,-Bstatic");
}
let search_path = archive_search_paths(sess);
for l in staticlibs {
if takes_hints {
cmd.arg(format!("-l{}", l));
} else {
// -force_load is the OSX equivalent of --whole-archive, but it
// involves passing the full path to the library to link.
let lib = archive::find_library(l.as_slice(),
sess.targ_cfg.os,
search_path.as_slice(),
&sess.diagnostic().handler);
let mut v = b"-Wl,-force_load,".to_vec();
v.push_all(lib.as_vec());
cmd.arg(v.as_slice());
}
}
if takes_hints {
cmd.arg("-Wl,--no-whole-archive").arg("-Wl,-Bdynamic");
}

for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
for &(ref l, kind) in others {
match kind {
cstore::NativeUnknown | cstore::NativeStatic => {
if takes_hints {
if kind == cstore::NativeStatic {
cmd.arg("-Wl,-Bstatic");
} else {
cmd.arg("-Wl,-Bdynamic");
}
}
cmd.arg(format!("-l{}", *l));
cstore::NativeUnknown => {
cmd.arg(format!("-l{}", l));
}
cstore::NativeFramework => {
cmd.arg("-framework");
cmd.arg(l.as_slice());
cmd.arg("-framework").arg(l.as_slice());
}
cstore::NativeStatic => unreachable!(),
}
}
if takes_hints {
cmd.arg("-Wl,-Bdynamic");
}
}

// # Rust Crate linking
Expand Down
51 changes: 27 additions & 24 deletions src/librustc_back/archive.rs
Expand Up @@ -95,6 +95,30 @@ fn run_ar(handler: &ErrorHandler, maybe_ar_prog: &Option<String>,
}
}

pub fn find_library(name: &str, os: abi::Os, search_paths: &[Path],
handler: &ErrorHandler) -> Path {
let (osprefix, osext) = match os {
abi::OsWin32 => ("", "lib"), _ => ("lib", "a"),
};
// On Windows, static libraries sometimes show up as libfoo.a and other
// times show up as foo.lib
let oslibname = format!("{}{}.{}", osprefix, name, osext);
let unixlibname = format!("lib{}.a", name);

for path in search_paths.iter() {
debug!("looking for {} inside {}", name, path.display());
let test = path.join(oslibname.as_slice());
if test.exists() { return test }
if oslibname != unixlibname {
let test = path.join(unixlibname.as_slice());
if test.exists() { return test }
}
}
handler.fatal(format!("could not find native static library `{}`, \
perhaps an -L flag is missing?",
name).as_slice());
}

impl<'a> Archive<'a> {
fn new(config: ArchiveConfig<'a>) -> Archive<'a> {
let ArchiveConfig { handler, dst, lib_search_paths, os, maybe_ar_prog } = config;
Expand Down Expand Up @@ -153,7 +177,9 @@ impl<'a> ArchiveBuilder<'a> {
/// Adds all of the contents of a native library to this archive. This will
/// search in the relevant locations for a library named `name`.
pub fn add_native_library(&mut self, name: &str) -> io::IoResult<()> {
let location = self.find_library(name);
let location = find_library(name, self.archive.os,
self.archive.lib_search_paths.as_slice(),
self.archive.handler);
self.add_archive(&location, name, [])
}

Expand Down Expand Up @@ -285,28 +311,5 @@ impl<'a> ArchiveBuilder<'a> {
}
Ok(())
}

fn find_library(&self, name: &str) -> Path {
let (osprefix, osext) = match self.archive.os {
abi::OsWin32 => ("", "lib"), _ => ("lib", "a"),
};
// On Windows, static libraries sometimes show up as libfoo.a and other
// times show up as foo.lib
let oslibname = format!("{}{}.{}", osprefix, name, osext);
let unixlibname = format!("lib{}.a", name);

for path in self.archive.lib_search_paths.iter() {
debug!("looking for {} inside {}", name, path.display());
let test = path.join(oslibname.as_slice());
if test.exists() { return test }
if oslibname != unixlibname {
let test = path.join(unixlibname.as_slice());
if test.exists() { return test }
}
}
self.archive.handler.fatal(format!("could not find native static library `{}`, \
perhaps an -L flag is missing?",
name).as_slice());
}
}

3 changes: 3 additions & 0 deletions src/librustrt/unwind.rs
Expand Up @@ -159,6 +159,9 @@ pub unsafe fn try(f: ||) -> ::core::result::Result<(), Box<Any + Send>> {
}

#[link(name = "rustrt_native", kind = "static")]
#[cfg(not(test))]
extern {}

extern {
// Rust's try-catch
// When f(...) returns normally, the return value is null.
Expand Down
3 changes: 3 additions & 0 deletions src/libstd/rt/backtrace.rs
Expand Up @@ -415,6 +415,9 @@ mod imp {
errnum: libc::c_int);
enum backtrace_state {}
#[link(name = "backtrace", kind = "static")]
#[cfg(not(test))]
extern {}

extern {
fn backtrace_create_state(filename: *const libc::c_char,
threaded: libc::c_int,
Expand Down
1 change: 1 addition & 0 deletions src/libstd/rtdeps.rs
Expand Up @@ -15,6 +15,7 @@
#![experimental]

// All platforms need to link to rustrt
#[cfg(not(test))]
#[link(name = "rust_builtin", kind = "static")]
extern {}

Expand Down
1 change: 0 additions & 1 deletion src/test/run-make/extern-fn-with-union/test.rs
Expand Up @@ -12,7 +12,6 @@ extern crate testcrate;

use std::mem;

#[link(name = "test", kind = "static")]
extern {
fn give_back(tu: testcrate::TestUnion) -> u64;
}
Expand Down
6 changes: 6 additions & 0 deletions src/test/run-make/issue-15460/Makefile
@@ -0,0 +1,6 @@
-include ../tools.mk

all: $(TMPDIR)/libfoo.a
$(RUSTC) foo.rs -C extra-filename=-383hf8
$(RUSTC) bar.rs
$(call RUN,bar)
14 changes: 14 additions & 0 deletions src/test/run-make/issue-15460/bar.rs
@@ -0,0 +1,14 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

extern crate foo;
fn main() {
unsafe { foo::foo() }
}
1 change: 1 addition & 0 deletions src/test/run-make/issue-15460/foo.c
@@ -0,0 +1 @@
void foo() {}
16 changes: 16 additions & 0 deletions src/test/run-make/issue-15460/foo.rs
@@ -0,0 +1,16 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![crate_type = "dylib"]

#[link(name = "foo", kind = "static")]
extern {
pub fn foo();
}
5 changes: 3 additions & 2 deletions src/test/run-make/no-duplicate-libs/Makefile
@@ -1,6 +1,7 @@
-include ../tools.mk

all: $(call STATICLIB,foo) $(call STATICLIB,bar)
all:
$(RUSTC) foo.rs
$(RUSTC) bar.rs
$(RUSTC) main.rs
$(call RUN,main)

21 changes: 21 additions & 0 deletions src/test/run-make/no-duplicate-libs/bar.rs
@@ -0,0 +1,21 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![no_std]
#![feature(lang_items)]
#![crate_type = "dylib"]

extern crate libc;

#[no_mangle]
pub extern fn bar() {}

#[lang = "stack_exhausted"] fn stack_exhausted() {}
#[lang = "eh_personality"] fn eh_personality() {}
21 changes: 21 additions & 0 deletions src/test/run-make/no-duplicate-libs/foo.rs
@@ -0,0 +1,21 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![no_std]
#![feature(lang_items)]
#![crate_type = "dylib"]

extern crate libc;

#[no_mangle]
pub extern fn foo() {}

#[lang = "stack_exhausted"] fn stack_exhausted() {}
#[lang = "eh_personality"] fn eh_personality() {}
1 change: 0 additions & 1 deletion src/test/run-pass/foreign-dupe.rs
Expand Up @@ -22,7 +22,6 @@ mod rustrt1 {
mod rustrt2 {
extern crate libc;

#[link(name = "rust_test_helpers")]
extern {
pub fn rust_get_test_int() -> libc::intptr_t;
}
Expand Down

9 comments on commit 1ae1461

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@bors bors commented on 1ae1461 Aug 4, 2014

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saw approval from brson
at alexcrichton@1ae1461

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@bors bors commented on 1ae1461 Aug 4, 2014

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merging alexcrichton/rust/issue-15460 = 1ae1461 into auto

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@bors bors commented on 1ae1461 Aug 4, 2014

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alexcrichton/rust/issue-15460 = 1ae1461 merged ok, testing candidate = 17ff116f

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@bors bors commented on 1ae1461 Aug 4, 2014

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@bors
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@bors bors commented on 1ae1461 Aug 4, 2014

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saw approval from brson
at alexcrichton@1ae1461

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@bors bors commented on 1ae1461 Aug 4, 2014

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merging alexcrichton/rust/issue-15460 = 1ae1461 into auto

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alexcrichton/rust/issue-15460 = 1ae1461 merged ok, testing candidate = 463d668

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@bors bors commented on 1ae1461 Aug 4, 2014

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fast-forwarding master to auto = 463d668

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