Build with extern llvm fails

[jauhien]

I have this issue:

I have the last llvm from the live ebuild on Gentoo installed (it means I have compiled the last version from llvm upstream git).

I try to compile rust using this llvm with commands

./configure --prefix=/usr --llvm-root=/usr --enable-clang
make

And I have this error:

jauhien@zcj rust % make
cfg: build triple x86_64-unknown-linux-gnu
cfg: host triples x86_64-unknown-linux-gnu
cfg: target triples x86_64-unknown-linux-gnu
cfg: enabling more debugging (CFG_ENABLE_DEBUG)
cfg: host for x86_64-unknown-linux-gnu is x86_64
cfg: os for x86_64-unknown-linux-gnu is unknown-linux-gnu
cfg: using CC=clang (CFG_CC)
cfg: using CXX=clang++ (CFG_CXX)
cfg: no pdflatex found, deferring to xelatex
cfg: no xelatex found, deferring to lualatex
cfg: no lualatex found, disabling LaTeX docs
cfg: no pandoc found, omitting PDF and EPUB docs
cfg: no llnextgen found, omitting grammar-verification
failed to run llconfig: args = `['/usr/bin/llvm-config', '--libs', '--system-libs', 'x86', 'arm', 'mips', 'ipo', 'bitreader', 'bitwriter', 'linker', 'asmparser', 'jit', 'mcjit', 'interpreter', 'instrumentation']`
llvm-config: unknown component name: arm

make: *** [/home/jauhien/work/rust/rust/src/librustc/lib/llvmdeps.rs] Error 1

What can be the reason for this? Is this something bad with rust or with my setup?

I'm trying to compile the version of rust from the commit 8e9e484

[alexcrichton]

This probably indicates that the copy of LLVM you installed did not have arm support built in. When building LLVM in-tree we configure ARM/x86/MIPS platforms simultaneously, which system LLVM distributions are not guaranteed to provide.

[jauhien]

How can I disable not relevant playforms in rust configure?

[jauhien]

Ok, I've found line 228 in mk/main.mk

Could disabling of these platforms be somehow added to configure?

[alexcrichton]

As I think you discovered in #14732, I suspect that disabling certain archs will require some finesse not only in the configure but also in the code itself. It's certainly all doable, however! I'd be fine with support being added.

[steveklabnik]

Triage: is this still relevant today?

[cardoe]

@steveklabnik: I'm trying to build Rust 1.7.0 on Gentoo with the system LLVM which happens to be 3.7.1. This issue is not occurring but its failing for another reason.

[ustcscgy]

Hello everyone, I just build rust 1.10.0 on Gentoo with llvm-3.8.0-r3(-multitarget), without errors.

BTW, currently build rust with clang on Gentoo has another bug (already on gentoo bug tracker).

[cardoe]

Yes. I've got support in Gentoo for Rust building against the Gentoo provided LLVM for some time now. This issue can be closed.

[alexcrichton]

Yay!