multiple definition link error when using multiple codegen units

[MagaTailor]

I wanted to use @dotdash's LLVM assertions patch but now my stage1 libstd fails to link. Probably unrelated but here it is:

rustc: arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/libstd
error: linking with `cc` failed: exit code: 1
note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-L" "/rust-master/arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.1.o" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.2.o" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.3.o" "-o" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/libstd-9026086f.so" "arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.metadata.o" "-Wl,-O1" "-nodefaultlibs" "-L" "arm-unknown-linux-gnueabihf/rt" "-L" "/rust-master/arm-unknown-linux-gnueabihf/llvm/Release+Asserts/lib" "-L" "/rust-master/arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib" "-Wl,-Bstatic" "-Wl,--whole-archive" "-l" "backtrace" "-Wl,--no-whole-archive" "-Wl,-Bdynamic" "-l" "dl" "-l" "pthread" "-l" "gcc_s" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/liballoc-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/librustc_unicode-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/liballoc_system-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/liblibc-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/librand-9026086f.rlib" "-Wl,--no-whole-archive" "-Wl,--whole-archive" "/tmp/rustc.FHfUQVlQsuoG/libcore-9026086f.rlib" "-Wl,--no-whole-archive" "-l" "c" "-l" "m" "-l" "rt" "-shared" "-Wl,-rpath,/home/odroid/rust-nightly-sysalloc-assert/lib/rustlib/arm-unknown-linux-gnueabihf/lib" "-Wl,--enable-new-dtags" "-s" "-l" "compiler-rt"

note: /tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `_$LT$core..option..Option$LT$T$GT$$GT$::map::h58518f67af9bf04e':
collections.0.rs:(.text._ZN38_$LT$core..option..Option$LT$T$GT$$GT$3map17h58518f67af9bf04eE+0x0): multiple definition of `_$LT$core..option..Option$LT$T$GT$$GT$::map::h58518f67af9bf04e'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN38_$LT$core..option..Option$LT$T$GT$$GT$3map17h58518f67af9bf04eE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::new::h0c1cdac7fb2b416c':
collections.0.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$3new17h0c1cdac7fb2b416cE+0x0): multiple definition of `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::new::h0c1cdac7fb2b416c'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.3.o:std.3.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$3new17h0c1cdac7fb2b416cE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::ptr::h4e14ee1392d1411e':
collections.0.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$3ptr17h4e14ee1392d1411eE+0x0): multiple definition of `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::ptr::h4e14ee1392d1411e'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$3ptr17h4e14ee1392d1411eE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::double::heaf5b97a8495eb9e':
collections.0.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$6double17heaf5b97a8495eb9eE+0x0): multiple definition of `_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$::double::heaf5b97a8495eb9e'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.3.o:std.3.rs:(.text._ZN40_$LT$alloc..raw_vec..RawVec$LT$T$GT$$GT$6double17heaf5b97a8495eb9eE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::uninitialized::he8ba150ad18eedcf':
collections.0.rs:(.text._ZN4core3mem13uninitialized17he8ba150ad18eedcfE+0x0): multiple definition of `core::mem::uninitialized::he8ba150ad18eedcf'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3mem13uninitialized17he8ba150ad18eedcfE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::uninitialized::hfa1a47f766d26f10':
collections.0.rs:(.text._ZN4core3mem13uninitialized17hfa1a47f766d26f10E+0x0): multiple definition of `core::mem::uninitialized::hfa1a47f766d26f10'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.3.o:std.3.rs:(.text._ZN4core3mem13uninitialized17hfa1a47f766d26f10E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::transmute_copy::h5f22bd4094d00101':
collections.0.rs:(.text._ZN4core3mem14transmute_copy17h5f22bd4094d00101E+0x0): multiple definition of `core::mem::transmute_copy::h5f22bd4094d00101'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3mem14transmute_copy17h5f22bd4094d00101E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::transmute_copy::h75f84324b8ee3166':
collections.0.rs:(.text._ZN4core3mem14transmute_copy17h75f84324b8ee3166E+0x0): multiple definition of `core::mem::transmute_copy::h75f84324b8ee3166'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.3.o:std.3.rs:(.text._ZN4core3mem14transmute_copy17h75f84324b8ee3166E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::forget::h502109c553961f51':
collections.0.rs:(.text._ZN4core3mem6forget17h502109c553961f51E+0x0): multiple definition of `core::mem::forget::h502109c553961f51'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3mem6forget17h502109c553961f51E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::size_of::hfb509be3c362d215':
collections.0.rs:(.text._ZN4core3mem7size_of17hfb509be3c362d215E+0x0): multiple definition of `core::mem::size_of::hfb509be3c362d215'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3mem7size_of17hfb509be3c362d215E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::mem::align_of::h2a452ce69533a17c':
collections.0.rs:(.text._ZN4core3mem8align_of17h2a452ce69533a17cE+0x0): multiple definition of `core::mem::align_of::h2a452ce69533a17c'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3mem8align_of17h2a452ce69533a17cE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::ptr::_$LT$impl$u20$$BP$mut$u20$T$GT$::is_null::h3fe8e4e4a8815d84':
collections.0.rs:(.text._ZN4core3ptr31_$LT$impl$u20$$BP$mut$u20$T$GT$7is_null17h3fe8e4e4a8815d84E+0x0): multiple definition of `core::ptr::_$LT$impl$u20$$BP$mut$u20$T$GT$::is_null::h3fe8e4e4a8815d84'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3ptr31_$LT$impl$u20$$BP$mut$u20$T$GT$7is_null17h3fe8e4e4a8815d84E+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::offset::he051aa5e5b8f8bfb':
collections.0.rs:(.text._ZN4core3ptr33_$LT$impl$u20$$BP$const$u20$T$GT$6offset17he051aa5e5b8f8bfbE+0x0): multiple definition of `core::ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::offset::he051aa5e5b8f8bfb'
arm-unknown-linux-gnueabihf/stage1/lib/rustlib/arm-unknown-linux-gnueabihf/lib/std-9026086f.0.o:std.0.rs:(.text._ZN4core3ptr33_$LT$impl$u20$$BP$const$u20$T$GT$6offset17he051aa5e5b8f8bfbE+0x0): first defined here
/tmp/rustc.FHfUQVlQsuoG/libcollections-9026086f.rlib(collections-9026086f.0.o): In function `core::ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::is_null::h630d425861f40502':
collections.0.rs:(.text._ZN4core3ptr33_$LT$impl$u20$$BP$const$u20$T$GT$7is_null17h630d425861f40502E+0x0): multiple definition of `core::ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::is_null::h630d425861f40502'

and so on. Configured with --enable-optimize --disable-jemalloc --enable-llvm-assertions and RUSTFLAGS='-C codegen-units=4 -C link-args=-s'

Are all these errors about memory management functions? (--disable-jemalloc broken again?)

[sanxiyn]

Does it happen without codegen-units option?

[MagaTailor]

Ha, good question, let me check! It used to work fine even with codegen units maybe a week ago.

[MagaTailor]

@sanxiyn You were right, it was parallel codegen causing problems here.

However, when it used to work, the llvm builds were just the regular Release ones, never with assertions enabled. (probably irrelevant)

My guess is one of the recent llvm updates is causing all that pain on ARM. (here and here)

[alexcrichton]

cc @nikomatsakis, perhaps this is a regression from #32469

[alexcrichton]

This error also isn't related to ARM, you can reproduce with a bootstrap with some number of codegen units (I used 8 locally)

[dotdash]

Minimized:

cgu.rs

#![crate_type="lib"]
pub fn id<T>(t: T) {
}

a.rs

#![crate_type="lib"]
extern crate cgu;
pub mod a {
    pub fn a() {
        ::cgu::id(());
    }
}
pub mod b {
    pub fn a() {
        ::cgu::id(());
    }
}

b.rs

#![crate_type="lib"]
extern crate cgu;
pub mod a {
    pub fn a() {
        ::cgu::id(());
    }
}
pub mod b {
    pub fn a() {
        ::cgu::id(());
    }
}

main.rs

extern crate a;
extern crate b;
fn main() {
  a::a::a();
  b::a::a();
}

The problem here is that the id function no longer gets internal linkage when it's used in more than one codegen unit.

[nikomatsakis]

Seems likely to be a regression, yes. @dotdash, I take it from the assignment that you are fixing it? (If so, how do you plan to do so?)