1350036 - MACOSX_DEPLOYMENT_TARGET needed when building with LLVM from source

Status: RESOLVED FIXED

(Firefox Build System :: General, defect)

Description

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

In order to enable Stylo on macOS 10.12, I installed LLVM via `brew install llvm`.  (In the past, I have compiled Gecko just fine with Apple's supplied clang.)

When using this particular LLVM (clang version 4.0.0), ./mach configure fails with:

```
     0:09.18 checking for gcc... /usr/local/opt/llvm/bin/clang -std=gnu99
     0:09.24 checking whether the C compiler (/usr/local/opt/llvm/bin/clang -std=gnu99  ) works... no
     0:09.24 configure: error: installation or configuration problem: C compiler cannot create executables.
     0:09.24 DEBUG: <truncated - see config.log for full output>
     0:09.24 DEBUG:
     0:09.24 DEBUG: configure:897: checking host system type
     0:09.24 DEBUG: configure:918: checking target system type
     0:09.24 DEBUG: configure:936: checking build system type
     0:09.24 DEBUG: configure:2220: checking for gcc
     0:09.24 DEBUG: configure:2333: checking whether the C compiler (/usr/local/opt/llvm/bin/clang -std=gnu99  ) works
     0:09.24 DEBUG: configure:2349: /usr/local/opt/llvm/bin/clang -std=gnu99 -o conftest    conftest.c  1>&5
     0:09.24 DEBUG: configure:2346:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
     0:09.24 DEBUG: main(){return(0);}
     0:09.24 DEBUG: ^
     0:09.24 DEBUG: 1 warning generated.
     0:09.24 DEBUG: ld: library not found for -lcrt1.10.6.o
     0:09.24 DEBUG: clang-4.0: error: linker command failed with exit code 1 (use -v to see invocation)
     0:09.24 DEBUG: configure: failed program was:
     0:09.24 DEBUG:
     0:09.24 DEBUG: #line 2344 "configure"
     0:09.24 DEBUG: #include "confdefs.h"
     0:09.24 DEBUG:
     0:09.24 DEBUG: main(){return(0);}
     0:09.24 DEBUG: configure: error: installation or configuration problem: C compiler cannot create executables.
     0:09.24 ERROR: old-configure failed
     0:09.27 *** Fix above errors and then restart with               "/Applications/Xcode.app/Contents/Developer/usr/bin/make -f client.mk build"
     0:09.27 make: *** [configure] Error 1 
```

On IRC, :froydnj suggested setting MACOSX_DEPLOYMENT_TARGET=10.9, and indeed that works.  We should pass this along by default where needed.

Comment 1

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

:bholley, have you heard of anyone else hitting this on macOS?  If it's not just me, maybe we need to fix this before we can build Stylo by default?

Comment 2

[Bobby Holley (:bholley)]

(In reply to J. Ryan Stinnett [:jryans] (use ni?) from comment #1)
> :bholley, have you heard of anyone else hitting this on macOS?  If it's not
> just me, maybe we need to fix this before we can build Stylo by default?

Hm, I don't think the expectation is to compile Gecko with the homebrew clang, just to run bindgen. I'm not sure why that's happening. I thought llvm was supposed to be a keg-only thing - did you tap it?

Comment 3

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

(In reply to Bobby Holley (:bholley) (busy with Stylo) from comment #2)
> (In reply to J. Ryan Stinnett [:jryans] (use ni?) from comment #1)
> > :bholley, have you heard of anyone else hitting this on macOS?  If it's not
> > just me, maybe we need to fix this before we can build Stylo by default?
> 
> Hm, I don't think the expectation is to compile Gecko with the homebrew
> clang, just to run bindgen. I'm not sure why that's happening. I thought
> llvm was supposed to be a keg-only thing - did you tap it?

I believe what happened is:

1. I installed LLVM 3.9 with `brew install llvm@3.9`
2. Try `./mach configure`, it errors with:

 0:01.69 checking for llvm-config... not found
 0:01.69 ERROR: Could not find LLVM/Clang installation for compiling stylo build-time
 0:01.69 bindgen.  Please put 'llvm-config' in your PATH, specify the
 0:01.69 'LLVM_CONFIG' environment variable, or pass the '--with-libclang-path'
 0:01.69 and '--with-clang-path' options to configure.

3. To satisfy this, I added `$(brew --prefix llvm@3.9)/bin` to my PATH (before /usr/bin).  However, this exposes not only `llvm-config` but also `clang` as well, overriding the system `clang` at /usr/bin/clang.

Looking at what was done in bug 1314355 for the bootstrap workflow, it appears we're recommending to instead export only the LLVM_CONFIG env var in .mozconfig.  Changing to that seems to work.

So, I guess we don't need to fix anything here, at least not for Stylo.

Comment 4

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

I'll leave it up to the build peers to decide if this is useful to investigate for other use cases of custom `clang` versions, or to close since Stylo is able to proceed without it.

Comment 5

[Mike Hommey [:glandium]]

Maybe putting LLVM_CONFIG first in that error message in comment 3 would help a little.

Comment 6

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Attachment: Bug 1350036 - Clarify llvm-config detection error.

Reword the `llvm-config` detection error message to recommend setting the
LLVM_CONFIG env var, like we do for the bootstrap path.  This avoids exposing
`clang` as well, so the compiler won't be changed.

Review commit: https://reviewboard.mozilla.org/r/139764/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/139764/

Comment 7

[Nathan Froyd [:froydnj]]

Comment on attachment 8868151 [details]
Bug 1350036 - Clarify llvm-config detection error.

https://reviewboard.mozilla.org/r/139764/#review143074

Thanks!

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/21ae7e6b4b44
Clarify llvm-config detection error. r=froydnj

Comment 9

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/21ae7e6b4b44