plotfi marked 2 inline comments as done.
plotfi added inline comments.
================
Comment at: cfe/trunk/unittests/DirectoryWatcher/DirectoryWatcherTest.cpp:287
/*waitForInitialSync=*/true);
+ if (!DW) return;
----------------
gribozavr wrote:
> plotfi wrote:
> > gribozavr wrote:
> > > plotfi wrote:
> > > > gribozavr wrote:
> > > > > Why? This is a test -- ignoring errors would only hide them from
> > > > > developers.
> > > > Please see how llvm::Expected works. This does not ignore or hide
> > > > anything.
> > > I think I know how llvm::Expected works.
> > >
> > > The problem that this check and return hides is that if
> > > DirectoryWatcher::create returns an error, the rest of the test is
> > > silently slipped. The test should be using something like `cantFail`
> > > instead.
> > If DirectoryWatcher returns an error and you hit the early return, without
> > taking the error the Expected destructor will print a callstack and halt
> > the program. I can check this again, but I am quite sure that without
> > invoking something like takeError you will hit the crash in the case of an
> > early return.
> That's good -- but I think a `cantFail` call would be more readable.
Ah, you should have said so then. Except this is arguably worse. I want this
test to tell me that the cause of the crash (in this case, exceeding the
inotify limit). What I want to happen is:
```
Note: Google Test filter = DirectoryWatcherTest.AddFiles
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from DirectoryWatcherTest
[ RUN ] DirectoryWatcherTest.AddFiles
Expected<T> must be checked before access or destruction.
Unchecked Expected<T> contained error:
inotify_init1() error: out of inotify entries #0 0x0000000000246b8f
llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/mnt/nvme0/llvm-project/llvm/lib/Support/Unix/Signals.inc:533:13
#1 0x00000000002450d2 llvm::sys::RunSignalHandlers()
/mnt/nvme0/llvm-project/llvm/lib/Support/Signals.cpp:69:18
#2 0x0000000000247268 SignalHandler(int)
/mnt/nvme0/llvm-project/llvm/lib/Support/Unix/Signals.inc:385:1
#3 0x00007f17924eb890 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
#4 0x00007f1790f94e97 gsignal /build/glibc-OTsEL5/glibc-
...
```
Wrapping the llvm::Expected in a cantFail hides this message, and instead you
get the much less useful:
```
Note: Google Test filter = DirectoryWatcherTest.AddFiles
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from DirectoryWatcherTest
[ RUN ] DirectoryWatcherTest.AddFiles
Failure value returned from cantFail wrapped call
UNREACHABLE executed at
/mnt/nvme0/llvm-project/llvm/include/llvm/Support/Error.h:707!
#0 0x0000000000246e0f llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/mnt/nvme0/llvm-project/llvm/lib/Support/Unix/Signals.inc:533:13
#1 0x0000000000245352 llvm::sys::RunSignalHandlers()
/mnt/nvme0/llvm-project/llvm/lib/Support/Signals.cpp:69:18
#2 0x00000000002474e8 SignalHandler(int)
/mnt/nvme0/llvm-project/llvm/lib/Support/Unix/Signals.inc:385:1
#3 0x00007f20c64a8890 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
#4 0x00007f20c4f51e97 gsignal
/build/glibc-OTsEL5/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
#5 0x00007f20c4f53801 abort /build/glibc-OTsEL5/glibc-2.27/stdlib/abort.c:81:0
#6 0x0000000000232b31
(build/tools/clang/unittests/DirectoryWatcher/./DirectoryWatcherTests+0x232b31)
```
I can add comments assuring that llvm::Expected will dump an error prior to
halting, but I specifically _want_ llvm::Expected to propagate up what perror
would print to the console otherwise.
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D65704/new/
https://reviews.llvm.org/D65704
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