Building Main/StackSetupShim triggers un-silenceable -nopie warnings with clang

[patrickt]

General summary/comments

In attempting to upgrade a library (haskell-tree-sitter) to a newer Stackage nightly (nightly-2018-05-04, for GHC 8.4, but nightly-2018-04-25 exhibits this problem too), the build process (with a custom Setup.hs) always generates the following errors from clang:

haskell-tree-sitter-0.1.0: configure (lib)
[1 of 2] Compiling Main             ( /Users/patrickt/src/haskell-tree-sitter/Setup.hs, /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup/Main.o )
[2 of 2] Compiling StackSetupShim   ( /Users/patrickt/.stack/setup-exe-src/setup-shim-mPHDZzAJ.hs, /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup/StackSetupShim.o )
Linking /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup/setup ...
clang: warning: argument unused during compilation: '-nopie' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-nopie' [-Wunused-command-line-argument]

These errors also appear when compiling dependent C code in the project itself; I was able to fix them with the following stanza in my stack.yaml:

apply-ghc-options: everything
ghc-options:
  $everything: -optc -Wno-unused-command-line-argument

However, I'm unable to figure out how to silence these warnings when building the setup executable. Adding a GHC_OPTIONS stanza to my Setup.hs did not work, nor did adding ccOptions = "-Wno-unused-command-line-argument" to my Setup.hs's libBuildInfo. Short of editing ~/.stack/programs/x86_64-osx/ghc-8.4.1/lib/ghc-8.4.1/settings on every machine we use, is there a way to silence these warnings? This makes upgrading to 8.4 a tricky proposition.

I am running macOS 10.13.4 with stack 1.7.1. The output of clang --version is

Apple LLVM version 9.1.0 (clang-902.0.39.1)
Target: x86_64-apple-darwin17.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Running with --verbose seems to indicate that the command producing these warnings is

2018-05-04 12:46:29.295442: [debug] Run process: /Users/patrickt/.stack/programs/x86_64-osx/ghc-8.4.2/bin/ghc-8.4.2 --make -odir /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup -hidir /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup -i -i. -clear-package-db -global-package-db -package-db=/Users/patrickt/.stack/snapshots/x86_64-osx/nightly-2018-04-25/8.4.2/pkgdb -package-db=/Users/patrickt/src/haskell-tree-sitter/.stack-work/install/x86_64-osx/nightly-2018-04-25/8.4.2/pkgdb -hide-all-packages -package-id=Cabal-2.2.0.1 -package-id=base-4.11.1.0 -package-id=directory-1.3.1.5 -package-id=process-1.6.3.0 -optP-include -optP/Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup/setup_macros.h /Users/patrickt/src/haskell-tree-sitter/Setup.hs /Users/patrickt/.stack/setup-exe-src/setup-shim-mPHDZzAJ.hs -main-is StackSetupShim.mainOverride -o /Users/patrickt/src/haskell-tree-sitter/.stack-work/dist/x86_64-osx/Cabal-2.2.0.1/setup/setup -threaded

Steps to reproduce

1. Check out [email protected]:tree-sitter/haskell-tree-sitter.git
2. Switch to the tentative-8.4-upgrade branch
3. Run script/bootstrap to fetch submodules
4. Run stack build

Expected

A clean build free of C errors.

Actual

Seemingly-unsilenceable errors from clang.

Stack version

$ stack --version
Version 1.7.1, Git revision 681c800873816c022739ca7ed14755e85a579565 (5807 commits) x86_64 hpack-0.28.2

Method of installation

• Official binary, downloaded from stackage.org or fpcomplete's package repository, and stack upgrade since.

EDIT: fixed repository link

[OlivierSohn]

I encounter the same warning when building this branch of my project with recent stack nightly distributions + clang.

[sebeaumont]

Me too.

clang: warning: argument unused during compilation: '-nopie' [-Wunused-command-line-argument]

stack from homebrew
haskell-stack: stable 1.7.1 (bottled), HEAD
The Haskell Tool Stack

stack itself says this is an unsupported build! wot?

[patrickt]

A follow-up: I've upgraded to stack HEAD (Version 1.8.0, Git revision 252bc7f051f34b1cfc9cb4cfa5ec35b2f8a2d2f6 x86_64 hpack-0.28.2) and still see this error.

[oluckyman]

I'm getting clang warning in completely new project:

$ stack new newProject
$ cd newProject
$ stack setup

clang: warning: argument unused during compilation: '-nopie' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-nopie' [-Wunused-command-line-argument]
stack will use a sandboxed GHC it installed
For more information on paths, see 'stack path' and 'stack exec env'
To use this GHC and packages outside of a project, consider using:
stack ghc, stack ghci, stack runghc, or stack exec

$ stack upgrade

Current Stack version: 1.7.1, available download version: 1.7.1

macOS 10.13.4

[ncaq]

relation
clang: error: unknown argument: '-no-pie' on darwin macOS High Sierra 10.13.4 · Issue #304 · haskell/haskell-platform

[oluckyman]

@ncaq thanks for the reference!
I've managed to fix that warning by editing settings in ~/.stack/programs/... folder. This is where stack installs ghc to isolate it from system-wide ghc

[sebeaumont]

@oluckyman setting:

[...
 ("C compiler supports -no-pie", "NO"),
...]

in .stack/programs/x86_64-osx/ghc-8.2.2/lib/ghc-8.2.2/settings silenced the warning for me also... and that's a useful file to know about to patch future incompatibilities with the Apple toolchain after updating it (it's not like we've not been here before).

[dbaynard]

This is probably an upstream issue https://ghc.haskell.org/trac/ghc/ticket/15112 which unfortunately doesn't look near being closed. According to that, there's an incompatibility with XCode's clang. Specifying the c compiler to use may help (although --with-gcc has its own issues, with Cabal).

The workaround looks like the best approach, for now, though there should probably be some documentation fixes for os x.

It may be possible to edit the default settings, though.

[MMMartt]

@ncaq thanks for the reference!
I've managed to fix that warning by editing settings in ~/.stack/programs/... folder. This is where stack installs ghc to isolate it from system-wide ghc

Replacing gcc(clang) in "C compiler command" field with brew installed gcc works for me.

[dbaynard]

A documentation PR would be good — would @ncaq, @MMMartt or anybody else like to contribute?

[dbaynard]

Closing as #4392 adds documentation.