Compile fails on musl libc (Subprocess.h)

[jprjr]

Hi there -

I'm working on getting hhvm running on a musl-based Linux distro, and I'm getting an error when compiling folly:

[  3%] Building CXX object third-party/folly/CMakeFiles/folly.dir/src/folly/Subprocess.cpp.o
In file included from /builddir/hhvm-HHVM-3.9.0/third-party/folly/src/folly/Subprocess.cpp:21:0:
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h: In static member function 'static folly::Subprocess::Options folly::Subprocess::pipeStdin()':
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h:361:49: error: expected unqualified-id before '(' token
   static Options pipeStdin() { return Options().stdin(PIPE); }
                                                 ^
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h: In static member function 'static folly::Subprocess::Options folly::Subprocess::pipeStdout()':
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h:362:50: error: expected unqualified-id before '(' token
   static Options pipeStdout() { return Options().stdout(PIPE); }
                                                  ^
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h: In static member function 'static folly::Subprocess::Options folly::Subprocess::pipeStderr()':
/builddir/hhvm-HHVM-3.9.0/third-party/folly/folly/Subprocess.h:363:50: error: expected unqualified-id before '(' token
   static Options pipeStderr() { return Options().stderr(PIPE); }
                                                  ^
third-party/folly/CMakeFiles/folly.dir/build.make:767: recipe for target 'third-party/folly/CMakeFiles/folly.dir/src/folly/Subprocess.cpp.o' failed
make[2]: *** [third-party/folly/CMakeFiles/folly.dir/src/folly/Subprocess.cpp.o] Error 1
CMakeFiles/Makefile2:176: recipe for target 'third-party/folly/CMakeFiles/folly.dir/all' failed
make[1]: *** [third-party/folly/CMakeFiles/folly.dir/all] Error 2
Makefile:116: recipe for target 'all' failed
make: *** [all] Error 2

I believe the error is that stdin, stdout, and stderr are all macros which are being expanded.

glibc defines stdin stdout stderr as:

extern struct _IO_FILE *stdin;
extern struct _IO_FILE *stdout;
extern struct _IO_FILE *stderr;
#define stdin stdin
#define stdout stdout
#define stderr stderr

musl libc defines them as:

extern FILE *const stdin;
extern FILE *const stdout;
extern FILE *const stderr;
#define stdin  (stdin)
#define stdout  (stdout)
#define stderr  (stderr)

So when compiling, lines 361-363 are expanded to:

static Options pipeStdin() { return Options().(stdin)(PIPE); }
static Options pipeStdout() { return Options().(stdout)(PIPE); }
static Options pipeStderr() { return Options().(stderr)(PIPE); }

Which leads to the above error.

I believe ISO C defines that stdin, stdout, and stderr are supposed to be macros. LLVM had some similar problem here: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130506/173690.html - this post describes what stdin stdout and stderr are supposed to be better than I could.

I'm not sure what the right way to fix this is - maybe something like #undef stdin (etc) towards the beginning of the code, then redefine it towards the end?

[Orvid]

As a note, MSVC defines stdin, stdout, and stderr as macros that call a function, so a fix here may help MSVC as well.

[zerotens]

@jprjr
You can comment these lines out until a proper fix is released.
They are just used for testing the library. (make test)

[c4milo]

I'm running into a similar issue as well with v2018.03.19.00.tar.gz release

[Orvid]

@c4milo That is a different issue than this one, which I fixed > 1 year ago (2f6eb18). Which compiler are you trying to build with?