[swift-dev] need help with GLibc module map problem

[David P Grove]

As part of helping to resolve old libdispatch pull requests, I have run
into a problem with the GLibc module map on Linux that I need help
understanding and fixing.

The symptom I am trying to resolve is that somewhere between the March 16
and March 24 Swift development snapshots, the Dispatch overlay for
libdispatch on Linux stopped building.  We've been hacking around the
problem for 2 months (
https://github.com/apple/swift-corelibs-libdispatch/pull/62), but we don't
want to merge that hack back to the master branch of libdispatch.

The issue is that swiftc is convinced that off_t and mode_t should be
defined in the stdio module (by including stdio.h).  We don't want to
include stdio.h in dispatch.h;  it is sufficient (and the C compilation of
libdispatch succeeds) to only include fcntl.h and unistd.h.  However
without including stdio.h in dispatch.h, building the swiftmodule from
Dispatch.swift fails, starting with the March 24 driver (and is still
broken on master as of this morning).

I can hack around this by (a) including stdio.h in dispatch.h  or (b)
editing glibc.modulemap.gyb to put the module statements for fnctl and
unistd before the modile statement for stdio.   Neither of these seem like
the right fix.

Can anyone point me to a better solution?

I've attached the full buildlog.   The actual build errors are excerpted
below as well.

thanks,

--dave

(See attached file: buildLog.txt)

make[2]: Entering directory
'/home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src'
/home/dgrove/swift/build/dpg/swift-linux-x86_64/bin/swiftc -Xcc
-fmodule-map-file=/home/dgrove/swift/swift-corelibs-libdispatch/dispatch/module.map
 -I/home/dgrove/swift/swift-corelibs-libdispatch -parse-as-library -Xcc
-fblocks -c
-o /home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src/Dispatch.o /home/dgrove/swift/swift-corelibs-libdispatch/src/swift/Dispatch.swift
<module-includes>:1:10: note: in file included from <module-includes>:1:
#include "dispatch.h"
         ^
/home/dgrove/swift/swift-corelibs-libdispatch/dispatch/dispatch.h:59:10:
note: in file included
from /home/dgrove/swift/swift-corelibs-libdispatch/dispatch/dispatch.h:59:
#include <dispatch/io.h>
         ^
/home/dgrove/swift/swift-corelibs-libdispatch/dispatch/io.h:253:31: error:
declaration of 'mode_t' must be imported from module
'SwiftGlibc.POSIX.sys.types' before it is required
        const char *path, int oflag, mode_t mode,
                                     ^
/usr/include/x86_64-linux-gnu/sys/types.h:70:18: note: previous declaration
is here
typedef __mode_t mode_t;
                 ^
<module-includes>:1:10: note: in file included from <module-includes>:1:
#include "dispatch.h"
         ^
/home/dgrove/swift/swift-corelibs-libdispatch/dispatch/dispatch.h:59:10:
note: in file included
from /home/dgrove/swift/swift-corelibs-libdispatch/dispatch/dispatch.h:59:
#include <dispatch/io.h>
         ^
/home/dgrove/swift/swift-corelibs-libdispatch/dispatch/io.h:355:2: error:
declaration of 'off_t' must be imported from module 'SwiftGlibc.C.stdio'
before it is required
        off_t offset,
        ^
/usr/include/stdio.h:90:17: note: previous declaration is here
typedef __off_t off_t;
                ^
/home/dgrove/swift/swift-corelibs-libdispatch/src/swift/Dispatch.swift:13:19:
 error: could not build Objective-C module 'Dispatch'
@_exported import Dispatch
                  ^
Makefile:909: recipe for target
'/home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src/Dispatch.o'
failed
make[2]: ***
[/home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src/Dispatch.o]
Error 1
make[2]: Leaving directory
'/home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src'
Makefile:493: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory
'/home/dgrove/swift/build/dpg/libdispatch-linux-x86_64/src'
Makefile:454: recipe for target 'all-recursive' failed
make: *** [all-recursive] Error 1
./utils/build-script: command terminated with a non-zero exit status 2,
aborting
./utils/build-script: command terminated with a non-zero exit status 1,
aborting
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